Front Cover
 Title Page
 List of contributors
 Table of Contents
 Historical sketch of the explorations...
 Marine meteorology of the Gulf...
 Physics and chemistry of gulf...
 Plant and animal communities
 Bacteria, fungi and unicellular...
 Sponges, coelenterates and...
 Free-living flatworms, nemerteans,...
 Parasitic worms
 Bryozoa, brachiopoda, phoronida,...
 Annelids and miscellaneous...
 Arthropods, xiphosura, pycnogonida,...
 Tunicates and lancelets
 Fishes and sea turtles
 The birds of the Gulf of Mexic...
 Mammals of the Gulf of Mexico
 Pollution of water

Group Title: Fishery bulletin - U.S. Fish and Wildlife Service ; 89
Title: Gulf of Mexico its origin, waters, and marine life
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00015464/00001
 Material Information
Title: Gulf of Mexico its origin, waters, and marine life
Series Title: Fishery bulletin - U.S. Fish and Wildlife Service ; 89
Physical Description: xiv, 604 p. : illus., maps. ; 26 cm.
Language: English
Creator: Galtsoff, Paul Simon, 1887-
Publisher: U.S. Govt. Print. Off.
Place of Publication: Washington, D. C.
Publication Date: 1954
Copyright Date: 1954
Subject: Marine biology -- Mexico, Gulf of   ( lcsh )
Geology -- Mexico, Gulf of   ( lcsh )
Mexico, Gulf of   ( lcsh )
Genre: bibliography   ( marcgt )
federal government publication   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: Prepared by American scientists under the sponsorship of the Fish and Wildlife Service, U.S. Dept. of the Interior, coordinated by Paul S. Galtsoff.
Bibliography: Includes bibliographical references.
 Record Information
Bibliographic ID: UF00015464
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltqf - AAA7907
ltuf - AKT4130
oclc - 00679884
alephbibnum - 002095385
lccn - 54060858
lccn - 54060858

Table of Contents
    Front Cover
        Page i
    Title Page
        Page ii
    List of contributors
        Page iii
        Page iv
        Page v
        Page vi
    Table of Contents
        Page vii
        Page viii
        Page ix
        Page x
        Page xi
        Page xii
        Page xiii
        Page xiv
    Historical sketch of the explorations in the Gulf of Mexico
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
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        Page 18
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        Page 20
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        Page 24
        Page 25
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        Page 35
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        Page 37
        Page 38
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        Page 40
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        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
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        Page 80
        Page 81
        Page 82
        Page 83
        Page 84
        Page 85
        Page 86
    Marine meteorology of the Gulf of Mexico
        Page 87
        Page 88
        Page 89
        Page 90
        Page 91
        Page 92
        Page 93
        Page 94
        Page 95
        Page 96
        Page 97
        Page 98
    Physics and chemistry of gulf waters
        Page 99
        Page 100
        Page 101
        Page 102
        Page 103
        Page 104
        Page 105
        Page 106
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        Page 154
        Page 155
        Page 156
        Page 157
        Page 158
        Page 159
        Page 160
    Plant and animal communities
        Page 161
        Page 162
        Page 163
        Page 164
        Page 165
        Page 166
        Page 167
        Page 168
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        Page 189
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        Page 206
        Page 207
        Page 208
        Page 209
        Page 210
        Page 211
        Page 212
        Page 213
        Page 214
    Bacteria, fungi and unicellular algae
        Page 215
        Page 216
        Page 217
        Page 218
        Page 219
        Page 220
        Page 221
        Page 222
        Page 223
        Page 224
        Page 225
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        Page 249
        Page 250
        Page 251
        Page 252
        Page 253
        Page 254
        Page 255
        Page 256
    Sponges, coelenterates and ctenophores
        Page 257
        Page 258
        Page 259
        Page 260
        Page 261
        Page 262
        Page 263
        Page 264
        Page 265
        Page 266
        Page 267
        Page 268
        Page 269
        Page 270
        Page 271
        Page 272
        Page 273
        Page 274
        Page 275
        Page 276
        Page 277
        Page 278
        Page 279
        Page 280
        Page 281
        Page 282
        Page 283
        Page 284
        Page 285
        Page 286
        Page 287
        Page 288
        Page 289
        Page 290
        Page 291
        Page 292
        Page 293
        Page 294
        Page 295
        Page 296
        Page 297
        Page 298
    Free-living flatworms, nemerteans, nematodes, tardigrades and chaetognaths
        Page 299
        Page 300
        Page 301
        Page 302
        Page 303
        Page 304
        Page 305
        Page 306
        Page 307
        Page 308
        Page 309
        Page 310
        Page 311
        Page 312
        Page 313
        Page 314
        Page 315
        Page 316
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        Page 318
        Page 319
        Page 320
        Page 321
        Page 322
        Page 323
        Page 324
        Page 325
        Page 326
        Page 327
        Page 328
        Page 329
        Page 330
    Parasitic worms
        Page 331
        Page 332
        Page 333
        Page 334
        Page 335
        Page 336
        Page 337
        Page 338
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        Page 352
        Page 353
        Page 354
        Page 355
        Page 356
        Page 357
        Page 358
    Bryozoa, brachiopoda, phoronida, and enteropneusta
        Page 359
        Page 360
        Page 361
        Page 362
        Page 363
        Page 364
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        Page 404
        Page 405
        Page 406
        Page 407
        Page 408
        Page 409
        Page 410
    Annelids and miscellaneous worms
        Page 411
        Page 412
        Page 413
        Page 414
        Page 415
        Page 416
        Page 417
        Page 418
        Page 419
        Page 420
    Arthropods, xiphosura, pycnogonida, and crustacea
        Page 421
        Page 422
        Page 423
        Page 424
        Page 425
        Page 426
        Page 427
        Page 428
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        Page 473
        Page 474
        Page 475
        Page 476
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        Page 486
        Page 487
        Page 488
        Page 489
        Page 490
        Page 491
        Page 492
    Tunicates and lancelets
        Page 493
        Page 494
        Page 495
        Page 496
        Page 497
        Page 498
        Page 499
        Page 500
    Fishes and sea turtles
        Page 501
        Page 502
        Page 503
        Page 504
        Page 505
        Page 506
        Page 507
        Page 508
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        Page 510
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        Page 512
        Page 513
        Page 514
        Page 515
        Page 516
    The birds of the Gulf of Mexico
        Page 517
        Page 518
        Page 519
        Page 520
        Page 521
        Page 522
        Page 523
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        Page 534
        Page 535
        Page 536
        Page 537
        Page 538
        Page 539
        Page 540
    Mammals of the Gulf of Mexico
        Page 541
        Page 542
        Page 543
        Page 544
        Page 545
        Page 546
        Page 547
        Page 548
        Page 549
        Page 550
        Page 551
        Page 552
    Pollution of water
        Page 553
        Page 554
        Page 555
        Page 556
        Page 557
        Page 558
        Page 559
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Full Text




Prepared by American scientists under the sponsorship of the
Fish and Wildlife Service, United States Department of the Interior
Coordinated by Paul S. Galtsoff





For sale by the Superintendent of Documents, U. S. Government Printing Office, Washington 25, D. C.
Price $3.25


Anderson, William W., Chief, Gulf Fishery Investigations, Fish and Wildlife
Banner, Albert H., Associate Professor of Zoology, University of Hawaii.
Bayer, Frederick M., Associate Curator, Division of Marine Invertebrates, U. S.
National Museum.
Behre, Ellinor H., Professor of Embryology, Louisiana State University.
Butler, Philip A., Fishery Research Biologist, Fish and Wildlife Service.
Chace, Fenner A., Jr., Curator, Division of Marine Invertebrates, U. S. National
Chandler, Asa C., Professor of Biology, Rice Institute.
Chitwood, B. G., formerly Professor of Biology, Catholic University of America.
Clark, Austin H., Associate, Department of Zoology, U. S. National Museum.
Coe, Wesley R., Professor Emeritus, Yale University.
Conger, Paul S., Associate Curator in Charge Diatom Collection, U. S. National
Cooper, G. Arthur, Associate Curator, Division of Invertebrate Paleontology and
Paleobotany, U. S. National Museum.
Davis, Charles C., Assistant Professor of Biology, Cleveland College, Western
Reserve University.
Deevey, Edward S., Jr., Osborn Zoological Laboratory, Yale University.
Deichmann, Elisabeth, Curator, Museum of Comparative Zoology, Harvard
Galtsoff, Paul S., Fishery Research Biologist, Fish and Wildlife Service.
Graham, Herbert W., Chief, North Atlantic Fishery Investigations, Fish and
Wildlife Service.
Gunter, Gordon, Acting Director, Institute of Marine Science, University of
Hartman, Olga, Allan Hancock Foundation, University of Southern California.
Hedgpeth, Joel W., Marine Biologist, Scripps Institution of Oceanography,
University of California.
Henry, Dora Priaulx, Oceanographic Laboratories, University of Washington.
Hyman, Libbie H., American Museum of Natural History.
Lasker, Reuben, Research Assistant, Marine Laboratory, University of Miami.
Leipper, Dale F., Head, Department of Oceanography, Agricultural and Mechanical
College of Texas.
Lindner, Milton J., Chief, Fishery Mission to Mexico, Foreign Service of the
U. S. A.
Lowery, George H., Jr., Museum of Zoology, Louisiana State University.
Lynch, S. A., Head, Department of Geology, Agricultural and Mechanical College
of Texas.
Manter, Harold W., Professor of Zoology, University of Nebraska.
Marmer, H. A., Late Assistant Chief, Division of Tides and Currents, U. S. Coast
and Geodetic Survey.


Moore, Hilary B., Assistant Director, Marine Laboratory, University of Miami.
Newman, Robert J., Museum of Zoology, Louisiana State University.
Osburn, Raymond C., Allan Hancock Foundation, University of Southern Cali-
Parker, Frances L., Scripps Institution of Oceanography, University of California.
Phleger, Fred B., Scripps Institution of Oceanography, University of California.
Pierce, E. Lowe, Associate Professor, Department of Biology, University of Florida.
Price, W. Armstrong, Department of Oceanography, Agricultural and Mechanical
College of Texas.
Relder, Harald A., Curator, Division of Mollusks, U. S. National Museum.
Rivas, Luis Rene, Associate Professor of Zoology, University of Miami.
Rounsefell, George A., Fishery Research Biologist, Fish and Wildlife Service.
Schmitt, Waldo L., Head Curator, Department of Zoology, U. S. National Museum.
Sears, Mary, Planktonologist, Woods Hole Oceanographic Institution.
Shigley, C. M., Dow Chemical Company.
Shoemaker, W. S., Department of Photographic Technology, Rochester Institute
of Technology.
Smith, F. G. Walton, Director, Marine Laboratory, University of Miami.
Sprague, Victor, Director, Lake Chatuge Biological Laboratory.
Taylor, Wm. Randolph, Professor of Botany, University of Michigan.
Thorne, Robert F., Professor of Botany, State University of Iowa.
Tierney, J. Q., Research Assistant, Marine Laboratory, University of Miami.
Timm, R. W., Catholic University of America.
Tressler, Willis L., U. S. Navy Hydrographic Office.
U. S. Public Health Service, Division of Water Pollution Control, Shellfish Branch,
Division of Sanitation.
Van Name, Willard G., Curator, American Museum of Natural History.
Voss, Gilbert L., Research Assistant, Marine Laboratory, University of Miami.
Williams, Robert H., Chairman, Department of Marine Sciences, Marine Labora-
tory, University of Miami.
ZoBell, Claude E., Professor of Microbiology, Scripps Institution of Oceanography,
University of California.


The purpose of this book is to summarize in a convenient form the present
knowledge about the Gulf of Mexico. Such a summary is needed in con-
nection with a large number of new investigations which are now being
conducted in the Gulf of Mexico by Federal and State organizations and
private institutions. It is hoped that the background information presented
here will be useful to the investigators engaged in the new research projects
and will save their time and effort.
Scientific data concerning the Gulf of Mexico have been accumulating
since the first explorations in the sixteenth century. They are scattered in
thousands of technical publications, some of them rare and not readily avail-
able to persons in the Gulf States.
The preparation of a digest of the existing knowledge about the Gulf was
suggested by a group of scientists attending, in November 1949, the meeting
of the Gulf and Caribbean Fisheries Institute at Miami. The idea, proposed
independently by Dr. Lionel A. Walford of the Fish and Wildlife Service
and Dr. Waldo L. Schmitt, head curator, Department of Zoology, U. S.
National Museum, was unanimously approved, and Paul S. Galtsoff was
selected to carry out the project. The magnitude of the task has proved
much greater than had been expected. Only through the hearty cooperation
of the 55 contributors to this volume has it been possible to complete the work
in about 3 years.
For the purpose of this book the Gulf of Mexico is defined as a partially
landlocked body of water indenting the southeastern periphery of the North
American Continent. Its eastern boundary was drawn from Cabo Catoche
at the tip of the YucatAn Peninsula to Key West at the southernmost tip of
Florida. This boundary does not constitute a natural barrier; it was arbi-
trarily determined because of the necessity of restricting the scope of the
project. Inland the area under consideration extends to the limits of tidal
The book comprises a number of articles each written by a recognized
authority in his field; these are arranged, with minor exceptions, in a taxo-
nomic order following a list of phyla, classes, and orders prepared in 1936
for the American Association for the Advancement of Science and published
by Duke University Press. This plan was carried out with the following
exceptions: the sections on Rotatoria and Branchiopoda were omitted be-
cause of the inability to find anyone willing to review these two groups; and,
for the sake of convenience, the articles on parasitic worms were assembled
in a single chapter.
A pertinent bibliography is given at the end of each section. A greater
number of bibliographical references, comprising more than 4,000 author and
subject cards, was prepared in cooperation with Mrs. Margaret M. Quat-
tromini of the Fish and Wildlife Service. The 12 sets of these files have been
assembled for distribution among the institutions engaged in research in the
Gulf of Mexico. No claim is made that these files are complete, and additional
items can be added as new references become available.


In organizing and carrying out the project, splendid cooperation and
valuable, suggestions were received from the contributors to the book. The
writer wishes to express his profound thanks to them for their continuous
interest, the great amount of work required to prepare the articles, and their
constructive criticism. Waldo L. Schmitt, head curator, U. S. National
Museum, and William Randolph Taylor showed unremitting interest in the
progress of the work, gave valuable advice in the formulation of the plan, and
were most helpful in suggesting some of the authors and persuading them to
undertake the review of various groups. My thanks are also due Richard S.
Green, Chief, Shellfish Branch, Division of Sanitation, Public Health Service
and A. F. Bartsch, biologist, Division of Water Pollution Control, Public
Health Service, for organizing the material in the chapter on water pollution;
to William S. von Arx of the Woods Hole Oceanographic Institution, Francis P.
Shepard of Scripps Institution of Oceanography, Remington Kellogg,
Director, U. S. National Museum, Frederick C. Lincoln, assistant to the
Director, Fish and Wildlife Service, and Isaac Ginsburg, Ichthyologist, Fish
and Wildlife Service, for valuable comments and constructive criticism of
certain parts of the book.
The work of Mrs. Margaret M. Quattromini in retyping the text and ar-
ranging the bibliographies is gratefully acknowledged.

Fishery Research Biologist.


I. Historical sketch of the explorations in the Gulf of Mexico. By Paul
S. Galtsoff ...----..---------------------------------------------- 3
Sources .....------ -------------------------------------------- 3
Pre-Columbian era----------------------------------- ------.-- 3
Discovery of the Gulf of Mexico 4--------------------------------- 4
Sixteenth and seventeenth centuries ------------------------------- 8
Eighteenth century ----------------------------------------- 18
From the beginning of the nineteenth century to the present time -------.. 22
Bibliography ----------------------------------------------- 32
II. Geology.
Shorelines and coasts of the Gulf of Mexico. By W. Armstrong Price ...---- 39
Status of studies of coasts and shorelines ------------------------- 39
Shoreline classification ----------------------------------------- 39
Sources of information ----------------------------------------- 42
Acknowledgments----------------------------------------------- 43
Structural and regional geo-oceanographic approach to shoreline descrip-
tion and classification--------------------------------------------- 43
Coasts and hinterland --- ..---------------------------------------- 43
Regional coastal types------------------------------------------ 44
Young orogenic coasts --------------------------------------- 44
Alluvial coasts --------------------------------------------- 46
Drowned limestone-plateau coastal plains ---------------------- 48
Biogenous environment .......------------------------------------ 50
Emergent and submergent shorelines of the Gulf ----------------------- 53
Use of terms --------------------------------------------------- 53
Submergent shoreline features --....---------------------------------- 54
Emergent shoreline features ........-------------------------------------- 55
Shoreline changes and processes -------------------------------------- 58
Shoreline simplification --------------------------------------- 58
Equilibrium profiles of continental shelf bottom ------------------- 59
Directions of longshore drift ------------------------------------ 62
References .....---------------------------------------------------- 62
Geology of the Gulf of Mexico. By S. A. Lynch ----------------------- 67
Early concepts --------------------------------------------- 67
Gulf coast geosyncline .. --------------------------------------- 68
Geomorphology of Gulf of Mexico -------------------------------- 71
General characteristics -------------------------------------- 71
Origin of major features ..------------------------------------- 71
Geomorphology by areas ----------------------------------72
Eastern Gulf area -------------------------------------- 73
Mississippi Delta area ----------------------------------- 73
Northern Gulf of Mexico -------------------------------- 74
Mexico-------------------------------------------- 75
Mexican Basin ----------------------------------------- 75
Sediments of Gulf of Mexico ------------------------------------- 75
Source of sediments ----------------------------------------- 75
Place of deposition---------------------------------------76
Early studies of submarine deposits -------------------------- 77
Recent studies of submarine deposits ...------------------------- 77
Sedimentary provinces.........------------------------------------ 78
Eastern Gulf -----------... ---..----------------------------- 78
Mississippi Delta ------------------------------------------ 80


II. Geology of the Gulf of Mexico-Continued
Sediments of Gulf of Mexico-Continued Page
Louisiana shelf ---------------------------------------------- 81
Western Gulf ---------------------------------------------- 81
Yucatan Peninsula .........--... --------------------------------------- 82
Cuba ----------------------------------------------------- 82
Mexican Basin---------------------------------- 82
Conclusions --------------------------------------------------- 82
Bibliography -------------------------------------------------- 83
III. Marine meteorology of the Gulf of Mexico, a brief review. By Dale F.
Leipper _---------------------------------------------------------89
Extra tropical cyclones.......---------------------------------------- 89
The general air circulation and some of its consequences ------------ 89
Average conditions_ --------------------------------------------- 90
Weather observing stations ------------------------------------ 93
Typical upper air soundings ------------------------------------- 93
Northers_ ------------------------------------------------------ 95
Meteorological tides ----------------------------------------- 95
Hurricanes ---------------------------------------------------- 96
Applications of marine meteorology in the Gulf ------------------- 96
Further sources of information ---------------------------------- 96
Conclusion ---------------------------------------------------- 97
Literature cited -------------------------------------------- 97
IV. Physics and chemistry of Gulf waters.
Tides and sea level in the Gulf of Mexico. By H. A. Marmer ----------- 101
Harmonic constants ------------------------------------------- 104
Types of tide ----....--------..------------------------------------- 108
Semidaily type----------------------------------------------- 110
Daily type ---------------------------------------------------110
Mixed types _-__---------------------------------------------- 112
Characteristics from harmonic constants ------------------------- 113
Disturbing effects of wind and weather --------------------------- 113
The tide in the Gulf of Mexico_ --------------------------------- 114
Sea level ------------------------------------------------------ 115
Availability of tidal data__ ---------------------------------------- 117
Literature cited ------------------------------------------------ 118
Physical oceanography of the Gulf of Mexico. By Dale F. Leipper ------ 119
Ocean currents___ --------------------------------------------- 119
Sea surface temperatures__--------------------------------------- 125
Sea temperature variations with depth --------------------------- 131
Salinity ------------------------------------------------------- 135
Temperature-salinity relationships ------------------------------- 135
Ocean wind waves and swell ------------------------------------ 136
Shallow water oceanography ------------------------------------- 136
Bibliography ----------------------------------------------- 136
Light penetration in the Gulf of Mexico. By William S. Shoemaker ----- 139
Distribution of chemical constituents of sea water in the Gulf of Mexico.
By Robert H. Williams --------------------------------------- 143
Salinity ----------...--------------------------------------------- 143
Dissolved oxygen ---------------------------------------------- 145
Phosphorus ------.... ------------------------------------------ 145
Nitrate-nitrogen -----------------------------------------------147
Nitrite-nitrogen ..........--------------------------------------------- 148
Hydrogen ion concentration (pH)-------------------------------- 148
Alkalinity and carbon dioxide components .------------------------ 148
Copper ------------------------------------------------------ 148
Miscellaneous chemical constituents ------------------------------148


IV. Distribution of chemical constituents of sea water-Continued Page
Summary ----------------------------------------------------- 149
Literature cited--------------- 150
The recovery of minerals from sea water. By C. M. Shigley------------ 153
V. Plant and animal communities.
Phytoplankton of the Gulf of Mexico. By Charles C. Davis ------------ 163
The zooplankton of the Gulf of Mexico. By Hilary B. Moore ----------- 171
Material ------------------------------------------------------ 171
Bibliography -------------------------------------------------- 172
Red tide. By Reuben Lasker and F. G. Walton Smith ----------------- 173
Sketch of the character of the marine algal vegetation of the shores of the
Gulf of Mexico. By Wm. Randolph Taylor ------------------------- 177
General nature of the flora ------------.------------------------ 177
Marine botanical studies of the Gulf of Mexico -------------------- 177
Collateral works of reference for the Gulf algal flora ---------------- 178
Chief types of algal vegetation ----------------------------------- 179
Shifting sandy beaches and estuarine mud flats ---------------- 179
Stable sand and mud; pools, small lagoons and coves ----------- 179
Protected coves and pools with a marine channel --------- 180
Protected bays and lagoons---------------------------------- 180
Mangrove thickets------------------------------------------ 180
Tidal streams --------------------------------------------- 180
Sandy shallows and "reefs" of shell and coral rubble ------------ 183
Rocky shores and inshore reefs------------------------------- 183
Pelagic seaweeds -------------------------------------- 185
Local features of the Gulf coast marine algal flora------------------ 186
Cited literature of Gulf of Mexico algae and bibliography of principal
works dealing with comparable West Indian marine algae-------- 189
Flowering plants of the waters and shores of the Gulf of Mexico. By
Robert F. Thorne------------------------------------------------ 193
Submarine meadow--------------------------------------------- 193
Mangrove swamp---------------------------------------------- 194
Salt marsh --------------------------------------------------- 196
Sand-strand vegetation ----------------------------------------- 198
Conclusion ---------------------------------------------------- 199
Bibliography -- ----------------------------------------- 199
Bottom communities of the Gulf of Mexico. By Joel W. Hedgpeth ------ 203
Investigations of recent facies----------------------------------- 205
The oyster community ----------------------------- 206
Serpuloid reefs -----------_ ------------------------------------- 210
The jetty community ------------------------------------------- 210
Sand beach communities---------------------------------------- 211
The shrimp ground community -------------------------------- --- 211
The coral and sponge communities -------------------------------- 213
Literature cited ---------- -------------------------- --------- 213
VI. Bacteria, fungi, and unicellular algae.
Marine bacteria and fungi in the Gulf of Mexico. By Claude E. ZoBell--- 217
Dinoflagellates of the Gulf of Mexico. By Herbert W. Graham---------- 223
Present status of diatom studies in the Gulf of Mexico. By Paul Conger- 227
Literature ----------------------------------------------------- 227
Campeche Bay ------------------------------------------------ 227
Mobile Bay--------------------------------------------------- 228
Tortugas and west coast of Florida ------------------------------- 228
Other records ------------------------------------------------- 228
Diatom floras of Gulf and adjacent waters ----------------------- 229
Ecology------------------------------------------------------- 229
Productivity ----------------------------------------------- 229
Silica relationships -. ------------------------------------------ 230
Bibliography --.- -----.----- ------ ----------------------------- 231


VII. Protozoa. Page
Gulf of Mexico Foraminifera. By Fred B. Phleger and Frances L. Parker- 235
Benthonic Foraminifera ------------------------------------- 235
Planktonic Foraminifera ..-------------------------------------- 241
Literature cited --------- -------------------------------------. 241
Protozoa. By Victor Sprague --------------------------------------- 243
Survey of the literature ...-------------------------------------- 243
Distribution of Protozoa---------.----------------------------. 244
Mastigophora-----------------------------------------------. 245
Sarcodina--------------------------------...----------------- 246
Sporozoa ------------------------------------------------------247
Unidentified species of Nematopsis ------------------------------ 249
Ciliata -------------------------------------------------- 251
Suctoria------------------------------------------------- 255
Literature cited------------------------------------------- 255
VIII. Sponges, coelenterates, and ctenophores.
The Porifera of the Gulf of Mexico. By J. Q. Tierney ----------------- 259
Biology of commercial sponges. By F. G. Walton Smith ---------------- 263
Hydroids of the Gulf of Mexico. By Edward S. Deevey, Jr ------------- 267
Collecting------------------------------------------------- 267
Zoogeography -....---------------------------------------------.. 268
Check list of Gulf of Mexico hydroids -------------------------- 269
Summary -----------...............--------------------------------..........------ 271
Literature cited ----------------------------------------------- 271
Hydromedusae of the Gulf of Mexico. By Mary Sears ----------------- 273
Siphonophores in the Gulf of Mexico. By Mary Sears ---------------- 275
Scyphozoa. By Joel W. Hedgpeth ----------------------------------- 277
Anthozoa: Alcyonaria. By Frederick M. Bayer... -----------------------279
Anthozoa: The anemones. By Joel W. Hedgpeth ---------------------. 285
Notes on common species-................------------------------- -----------287
Bibliography ---------------------------------------------- 290
Gulf of Mexico Madreporaria. By F. G. Walton Smith ----------------- 291
Ctenophores in the Gulf of Mexico. By Mary Sears -------------------. 297
IX. Free-living flatworms, nemerteans, nematodes, tardigrades, and chae-
Free-living flatworms [Turbellarial of the Gulf of Mexico. By L. H.
Hyman --------------------------------------------------------- 301
The nemertean fauna of the Gulf of Mexico. By Wesley R. Coe --------- 303
Geographical distribution ...---------------------.--------------- 303
Reproduction and regeneration--- ------------------------------ 304
Ecology ------------------------------------------------------ 304
Food --------------------------------------------------------- 304
Key for identification ------------------------------------------- 305
Systematic description of species --------------------------------- 305
Paleonemertea_ ----------------------------------------- 305
Heteronemertea- ------ ---------------------------------- 306
Hoplonemertea ------------------------------------------- 307
Bdellonemertea -------------------------------------------- 309
Bibliography ------------------------------------------------- 309
Echnioderida of the Gulf of Mexico. By B. G. Chitwood ------------ 311
Free-living nematodes of the Gulf of Mexico. By B. G. Chitwood and
R. W. Timm --------------------------------------------------- 313
Nematode anatomy ------------------------------------------- 313
Historical rsum -- ------------------------- ------------------ 314
Classified list of species ------------------------------------------ 314
Phasmidea------------------------------------------------- 314
Aphasmidea --------- ---------------------------------- 314


IX. Free-living nematodes of the Gulf of Mexico-Continued Page
Geographic distribution ---------------------- -- --- 318
Ecology and life habits ----------------------------------------- 319
Literature cited ---------------------------------------- -----.. 320
Tardigrades of the Gulf of Mexico. By B. G. Chitwood ---------.....- 325
Notes on the Chaetognatha of the Gulf of Mexico. By E. Lowe Pierce __ 327
Notes on the range of species collected in the Gulf of Mexico -------- 328
Summary --------------------- --- ------- ---- 328
Literature cited ------------------------------------------- 329
X. Parasitic worms.
Parasitic helminths. By Asa C. Chandler and Harold W. Manter ------- 333
Trematoda of the Gulf of Mexico. By Harold W. Manter- ------------- 335
Monogenea --------------------------------------------- -- 335
Aspidogastrea ------------------------------------------- -- 336
Digenea --------------------------------------------------- 336
Gasterostomata ------------------------------------------- 336
Prosostomata ---------------------------------------------- 336
Host specificity of trematodes of marine fishes of the Gulf of Mexico-- 342
The geographical distribution of trematodes of fishes at Tortugas,
Florida--- ------------------------------------------ 343
Trematodes of turtles ------------------------------------------- 345
Trematodes of birds-------------------------------------------- 346
Trematodes of mammals -------------------------------------- 346
Studies on larval stages and life cycles of trematodes of the Gulf of
Mexico------------------------------------------------------ 347
Summary ---------- ----------------------------------_----__. 348
Literature cited ------------------------------------------- 348
Cestoda. By Asa C. Chandler-------------------------------------- 351
Tetraphyllidea --------------------------------------------- 351
Trypanorhyncha ------------------------------------------ 352
Incertae sedis --------------------------------------------- 353
Pseudophylidea---------------------------------------------- 353
Cyclophyllidea --------------------------------------------- 353
Acanthocephala. By Asa C. Chandler ------------------------------- 355
Eoacanthocephala ---------------------------------------------- 355
Palaeacanthocephala ------------------------------------------ 355
Nematoda. By Asa C. Chandler..------------------------------------ 357
Ascaridata ---------.------------------------------------------ 357
Incertae sedis ---------------------------------------------- 358
Bibliography (Cestoda, Acanthocephala, Nematoda) ---------------- 358
XI. Bryozoa, Brachiopoda, Phoronida, and Enteropneusta.
The Bryozoa of the Gulf of Mexico. By Raymond C. Osburn ----------- 361
Brachiopoda occurring in the Gulf of Mexico. By G. Arthur Cooper ----- 363
Phoronida. By Joel W. Hedgpeth ----------------------------------- 367
Enteropneusta. By Joel W. Hedgpeth.....------------------------------ 369
XII. Echinoderm.
Echinoderms (other than holothurians) of the Gulf of Mexico. By Austin
H. Clark -------------------------------------------------------- 373
Crinoidea ----------------------------------------------------- 373
Echinoidea ---- ..------------------------------------------------ 374
Asteroidea ---------------------------------------------------- 375
Ophiuroidea ..-------------------------------------------------- 376
Bibliography ---------------------------------------------- 378
The holothurians of the Gulf of Mexico. By Elisabeth Deichmann---..--- 381
Technique---------------------------------------------------- 382
Key to the orders ---------------------------------------------- 383
Elasipoda ------------------------------------------------- 383
Aspidochirota ------------------------------------------------ 384


XII. The holothurians of the Gulf of Mexico-Continued Page
Dendrochirota -------------------------------------------------394
Molpadonia --------------------------------------------------- 405
Apoda -------------------------------------------------------- 406
Bibliography ------------------------------------------------- 408
XIII. Annelids and miscellaneous worms.
Polychaetous annelids of the Gulf of Mexico. By Olga Hartman -------- 413
Review of the families ----------------------------------------- 413
Appendix on some ecological associations -------------------------- 416
Literature cited ------------------------------------------------ 416
Miscellaneous vermes. By Joel W. Hedgpeth ------------------------- 419
Echiurida ---------------------------------------------------- 419
Sipunculida ---------------------------------------------------- 419
Literature cited ------------------------------------------------ 420
XIV. Arthropods: Xiphosura, Pycnogonida, and Crustacea.
Xiphosura. By Joel W. Hedgpeth ---------------------------------- 423
Pycnogonida. By Joel W. Hedgpeth ------------------------------- 425
Marine Ostracoda. By Willis L. Tressler ----------------------------- 429
Ecology ------------------------------------------------------- 430
Ostracoda reported from adjacent regions ------------------------- 436
Caribbean Sea (off Colon) -------------------------------- 436
West Indies ---------------------------------------------- 436
Cuba_ ---------------------------------------------------- 436
Bahama Islands---------------------------------------- 436
Conclusions --------------------------------------------------- 436
Bibliography ---_ ----------------------------------------------- 436
Copepoda. By Waldo L. Schmitt ---------------------------------- 439
Cirripedia. The barnacles of the Gulf of Mexico. By Dora Priaulx Henry-- 443
Mysidacea and Euphausiacea. By Albert H. Banner ----------------- 447
Stomatopoda. By Fenner A. Chace, Jr ------------------------------- 449
Decapoda of the Gulf of Mexico. By Ellinor H. Behre ----------------- 451
General physiographic regions --------- ----------------- 451
Comparison of faunas ---------------------------------------- 453
Reference collections----------------------------------------- 453
Papers of particular reference to Gulf decapods ------------------ 454
Biology of commercial shrimps. By Milton J. Lindner and William W.
Anderson ------------------------------------------------ 457
XV. Mollusks.
Biology of the spiny lobster. By F. G. Walton Smith ----------------- 463
Mollusks. By Harald A. Rehder-------------__------__--------------469
Past work done in this area -------------------------------------- 469
General--------------------------------------------------- 469
Florida --------------------------------------------------- 469
Alabama-Louisiana-_ ------------------------------------- 470
Texas ---------------------------------------------------- 470
Mexico --------------------------------------------------- 470
Cuba ------------------------------------------------ 470
Deeper waters --------------------------------------------- 471
Ecology ------------..------------------------------------------ 471
Caribbean Province --------------------------------------- 471
Carolinian Province ---------------------------------------- 472
Deeper waters of the Gulf of Mexico ------- -------------- 472
Bibliography ----------------------------------------------- 473
Cephalopoda of the Gulf of Mexico. By Gilbert L. Voss ---------------- 475
Systematic list ---....--------------------------------------------- 477
Literature cited --- _-----_- ----------------------------------- 477
Summary of our knowledge of the oyster in the Gulf of Mexico. By Philip
A. Butler--...--------------------------------------------------- 479
Oyster reefs of the Gulf of Mexico. By W. Armstrong Price --------------- 491


XVI. Tunicates and lancelets. Page
The Tunicata of the Gulf of Mexico. By Willard G. Van Name ------------...... 495
Ascidian fauna of the Gulf of Mexico------------------------------ 495
The pelagic Tunicata-------------------------------------------- 496
Bibliography ------------------- ------------ 497
The lancelets. Branchiostomidae. By Joel W. Hedgpeth ---------------- 499
XVII. Fishes and sea turtles.
The origin, relationships, and geographical distribution of the marine fishes
of the Gulf of Mexico. By Luis Rene Rivas ------------------------- 503
Shore fishes ------------------------------------------ 504
Pelagic fishes -------------------------------------------------- 505
Deep sea fishes --------------------------------------- 505
Literature cited ----------------------------------------- 505
Biology of the commercial fishes of the Gulf of Mexico. By George A.
Rounsefell -------------------------------------------- 507
Taxonomy and distribution of sea turtles. By F. G. Walton Smith--.----- 513
Family Cheloniidae ------------------------------------ -- 513
Family Dermochelidae ..----------------------------------------- 513
Key to the Gulf of Mexico sea turtles-...... 514
Distribution in the Gulf of Mexico------------------------------ 515
Bibliography --------------------------------------- 515
XVIII. The birds of the Gulf of Mexico. By George H. Lowery, Jr., and Robert
J. Newman --- -- ------------------------ --- 519
Offshore birds ----------------------------------------------- 520
Birds of the coast ----------------------------------------------- 526
Coastal breeding birds------------------------------------------- 529
Regular visitants on the coast ------------------------------------ 530
Visitants to coast not of regular annual occurrence ----------------- 532
Land birds over the open Gulf ---------------------------------- 535
Literature cited ------------------------------------------------- 538
XIX. Mammals of the Gulf of Mexico. By Gordon Gunter ------------------- 543
Pinnipedia -.------------------------------------- ---- 543
Sirenia -------------------------------------------------------- 543
Cetacea ---------------------------------------------------- 545
General information ---------------------------- -- 545
Cetaceans of the Gulf of Mexico ------------------------------ 546
Odontoceti. Toothed whales- ---------------------------- 546
Mysticeti. Baleen whales----------------------------------- 550
Literature cited ------------------------------------------- 550
XX. Pollution of water.
Aspects of water pollution in the coastal area of the Gulf of Mexico. Pre-
pared in the Division of Water Pollution Control, and Shellfish Branch,
Division of Sanitation, Public Health Service, U. S. Department of
Health, Education and Welfare------------------------- ----- 555
Nature of pollution affecting the Gulf waters ----------------------- 555
Water pollution control agencies, programs, and laws ----------------- 556
Florida -------------------------------- 557
Alabama ------------------------------------------------- 557
Mississippi ------------------------------------------------ 557
Louisiana -------------------------------------------------- 557
Texas ----------------------------------------------------- 557
Federal-State shellfish control program---------------------------- 557
Summary of water pollution data ----------558
Damages to resources caused by pollution ------------------------- 561
Lower Florida area 564
Peace River area---------------------------------------- 564
Tampa Bay area _------------------------------------------ 564
Withlacoochee River area ----------------------------------- 565


XX. Aspects of water pollution-Continued
Damages to resources caused by pollution-Continued Page
Suwannee River area------------------------------------- 565
Ochlockonee River area --------------------------------- 566
Apalachicola River area------------------------------------ 566
Choctawatchee River area ----------------------------------- 566
Perdido-Escambia area -------------------------------- 567
Mobile Bay area---------------------------------------.....-.. 567
Pascagoula River area- ------------------------- 568
Pearl River area- ------------------------------ 569
Lower Mississippi River area------------------------------ 569
Atchafalaya River area -------------------------------------- 569
Calcasieu River area---------------------------------------- 570
Sabine River area .---.--------------------------------------- 570
Neches River area--------------------------------------- 570
Trinity River area ------------------------------------------ 571
Brazos River area--------------------------------------.. 571
Colorado River area-------------------------------------... 572
Guadalupe River area------------------------------------ 572
Nueces River area--------------------------------------- 572
Lower Rio Grande area -------------------------------------- 573
The Gulf coast of the Republic of Mexico------------------------ 573
Literature cited_ ------------------------------------------- 574
Index .... ..-------------------------------------------------------- 577



By PAUL S. GALTSOFF, Fish and Wildlife Service, United States Department of the Interior

The brief historical sketch of discoveries and
explorations in the Gulf of Mexico presented in
this paper is based on published materials avail-
able in this country. Fortunately, the large
collection of books and maps in the Library of
Congress, Harvard University, American Geo-
graphical Society, and the Public Library of New
York York City provided abundant material from
which the progress of scientific knowledge of the
Gulf of Mexico could be traced with reasonable
completeness. A wealth of data about the earlier
discoveries in the Gulf can be found in the classical
works of Winsor (1884-89), Thacher (1896),
Lelewel (1852), in 20 volumes of history of voy-
ages by Provost (1746-89), Harrisse (1900), and
Fiske (1892).
A student of history of explorations in the New
World finds in the writing of Alexander von
Humboldt, especially his Examen Critique . .
(1836-39) a rich source of critical information.
A catalog of maps of the Spanish possessions
published by the Library of Congress under the
title, The Lowery Collection (Lowery 1912) not
only gives detailed descriptions of maps printed
from 1502 to 1820 but also contains a great
amount of information about the explorations
and cartography of the Gulf. A brief but com-
prehensive review of the explorations between
1492 and 1543 is given by Kohl (1863).
Many other publications and maps in various
institutions in the United States were consulted.
The more important of them are the catalog of
maps, British Museum (1884, 1885), the catalog
of geographical documents in the national library
in Paris (Paris, Bibliothqeue national, 1892),
Phillips' list of maps of America, list of geo-
graphical atlases (U. S. Library of Congress, 1901,
1909-20), and the description of Mexican maps
by Torres Lanzas (1900). The publications of
Phillips are listed in some libraries under his
name, while in others they appear only under his
titles (see Bibliography); the work of Torres
Lanzas may be found under "Spain," "Torres,"
259534 0-54-2

and "Lanzas." Other references not discussed
in the text are listed in the bibliography.
Reports, letters, and other documents written
by the earlier explorers show clearly that ad-
venture, military conquest, and search for fabulous
riches were the principal impelling forces that
lured thousands of men of the sixteenth and
seventeenth centuries to embark on the daring
voyages beyond the unknown western ocean.
Science played only a minor part in these risky
undertakings, and scientific observations made in
the course of these explorations, which so greatly
enhanced the knowledge of the inhabitable world,
were merely incidental byproducts of mercenary
or military ventures.
History of the discovery and colonization of
the New World is beyond the scope of this chapter.
The following pages contain, therefore, only a
brief summary of scientific achievements of the
many explorations in the Gulf of Mexico from the
time of its discovery to the present days. The
author hopes that the picture of the scientific
progress in the studies of the Gulf which he pre-
sents here has not been distorted by errors or


Written history of the explorations in the Gulf
of Mexico naturally begins with the discovery
of the New World by Columbus in 1492, but
long before the white man set foot on the shores
of the islands of America the existence of a large,
landlocked body of water now called the Gulf of
Mexico was known to the tribes that inhabited
its coastal plains and sailed and fished in its waters.
Indians living along the west coast of Florida did
not venture beyond a narrow coastal zone in which
they fished from small dugout canoes. This
conclusion is well substantiated by archaeological
research in Florida and especially by the study of
the contents of numerous shell heaps (Walker
1880, 1885; Wiley 1949), which contain the rem-


nants of birds, fishes, and mollusks found only
in coastal waters.
The Aztecs, who developed their own system of
navigation, were fairly well acquainted with
certain parts of the Gulf. This is probably true
also of the Mexican and Yucatec Indians, who
sailed over considerable distances off shore.
Evidence for this is given in the report of the
fourth voyage of Columbus, who on July 2,1502,
sighted a large Indian ship of the size of a Spanish
galley about 80 miles east of the Yucatan coast
(Kohl 1863).
The art of map making practiced by Aztecs had
reached a high degree of perfection as can be
judged from the incident described by Bernal
Diaz de Castillo (Hakluyt Society Works, 2d
ser., No. 24, p. 129, quoted from W. Lowery,
1912, p. 27). During the Cortes invasion of
Mexico, he writes, "The great Montezuma gave
our Captain a henequen cloth on which were
painted and marked very true to nature, all the
rivers and bays on the northern coast from PAnuco
to Tabasco, that is, for a matter of one hundred
and forty leagues, and the river of Coatzacoalcos
was marked on it."
For more than 1,400 years of the Christian era
the geography of the western world was under
the influence of the writings of Claudius Ptolemy,
an Egyptian who lived in Alexandria about the
middle of the second century (the dates of his
life are usually given as between 90 and 168
A. D.), and spent 40 years in making astronomical
observations. For many centuries Ptolemy's data
on the locations of many places on earth with
reference to the parallel of Alexandria were the
principal source of information for map makers.
No existing Ptolemy maps are known earlier than
that of the thirteenth century, the first printed
edition of which was executed in 1475 in Vicenza
(Thacher 1896).
Some idea of the type of maps available to
navigators at the end of the fifteenth and the
beginning of the sixteenth century can be gained
from examining figure 1 representing the map of
the world by Johannes Ruysch, copied from
Ptolemy's geography of 1507-08. The discovery
of the New World has been already incorporated
in it, and the name "Mundus novus" appears for
the first time on the engraved map.
During the last 40 years of the fifteenth century
the Portuguese seamen made persistent and almost

continuous efforts to search for new Atlantic
islands beyond the Azores. So far, no docu-
mentary proof has been found of the pre-
Columbian discovery of western lands by Portu-
guese, but, as stated by the Portuguese historian,
Antonio Baigo, . there are numerous in-
dications that the existence of other islands be-
yond the Azores was known or suspected in
Portugal. It was in the wake of these indications
that Columbus sailed. His voyage is integrated
with cycle of Portuguese explorations of the
Western Ocean." (Quoted from Morison, 1940,
p. 75.)
Because of the secrecy attached by the Portu-
guese Government to the discoveries of new
lands and their location, the findings of Portu-
guese seamen were lost, and only inconclusive
traces of their efforts remain on certain documents
originated in Lisbon. One of these is the famous
map by Alberto Cantino which is discussed in
the next section of this article (p. 8).
The discoverer of the New World came almost
to the very entrance of the Gulf of Mexico but
failed to enter it. On his second voyage, June
1494, Columbus followed the southern shores of
Cuba as far as Isla de Pinos, where he stopped.
Disregarding the information received from the
Indians that the end of the land was not far, he
changed his course and sailed eastward. The
decision was influenced by his strong belief that
Cuba represented the end of the new continent.
As it is generally known, he asked his companions
to sign a statement to this effect. The declaration,
however, was not universally accepted since the
earliest maps of the New World by Cosa, 1500
(fig. 3, p. 9), and Waldseemfiller, 1507 (fig. 2),
show Cuba (Isabella) as an island.
The question who was the first European ex-
plorer to sail along the coast of the American
continent is by no means settled. The credit is
usually given to the man whose name is forever
associated with the New World. Amerigo Ves-
pucci, the third son of a Florentine notary, was
born on March 9, 1451. He studied diligently
and became proficient in astronomy and in the use
of the astrolabe, but his principal interest was in a
commercial career. After establishing himself
as an agent for the House of Cadiz, Vespucci
undertook to settle the claims left after the death

FIGURE 1.-Portion of the world map by Johannes Ruysch from Ptolemy's geography of 1507-08.





2_ _---- _-- I_ z

t -o-- --r---------I----l-7- U,

E . . ...-, .. tb l

FIGURE 2.-Waldseemiiller map about 1507 showing the discoveries of Vespucci, from the Ptolemy geography printed in
Strassburg in 1513, known also as the Admiral's map. Reproduction from a copy in the Library of Congress.


of his friend, Juanito Berardi, who contracted to
supply and equip 12 vessels of 900 tons each for the
Spanish Crown. In 1497, at the request of the
king, Vespucci joined the expedition to the New
World. In his own words, "the King, Don
Fernando of Castile, being about to dispatch four
ships to discover new lands toward the west, I
was chosen to aid in making discovery" (Thacher
1896, p. 69). He never explained his exact
duties aboard the ship, but judging from his
previous experience in commercial methods he
probably went as a sort of supercargo to supervise
the distribution of food, to weigh the gold, and to
keep accurate tally of the Crown's share which,
according to the royal decree of 1495, was one-
third of the total gold obtained by the expeditions.
Vespucci started from Cadiz on May 10, 1497.
After reaching the Canary Islands in about 10
days, the fleet sailed west and quarter-southwest
for 37 days (27 days according to the Latin text
of Vespucci's letter) until land was sighted a
thousand leagues from the Canaries. Making
allowance for an error of 10 latitude and about 80
longitude, Thacher (1896) estimated that the
landfall would be off the coast of Honduras in the
vicinity of Cabo Gracias a Dios. It is interesting
to note that the ships passed between the islands
of the Caribbean without noticing them. A safe
harbor was found after 2 more days of sailing
northward. Vespucci describes how, skirting the
coast, he saw villages one of which, consisting of
40 houses, was built, like Venice-upon the water.
It was near this village that a fierce encounter
with Indians took place in which 15 or 20 natives
were killed. The place is probably on the shores
of Campeche Bay, north of Tabasco.
Continuing for 80 leagues farther along the
coast, the expedition came to a place inhabited
by different people. It was called the Province
of Lariab, a name which later on caused a great
deal of confusion and argument since in the Latin
edition of Vespucci's letter the name was trans-
lated "Parias," a mistake that led many to
believe that the explorer referred to the Gulf of
Paria off the Venezuelan coast discovered by
Columbus in 1498 during his third voyage.
According to Thacher, the word "Lariab" is a
compound word of Quiche dialect which means
"there are many." It is assumed that the expres-
sion was used by the natives, who misunderstood
the question addressed to them by Spaniards about

the name of their province and answered that
there were many people in the land. Vespucci
states that this land, which is probably near
Tampico in Mexico, is "within the torrid zone,
close or just under the parallel described by the
Tropic of Cancer where the pole of the horizon
has an elevation of 230 at the extremity of the
second climate." (Quoted from Thacher, 1896.)
The term "clima" (plural climatea") of ancient
Greek cartographers denotes parallel zone or belt,
the width of which, according to Hipparchus, is
determined by astronomical observations on the
basis of the longest day of the year.
The rest of the letter (Vespucci, 1926 edition)
caused endless arguments among geographers.
Vespucci states that from Lariab they navigated
in sight of land and covered 870 leagues, still
going in the direction of the "maestrale." This
course, corresponding to northwest, would have
brought the expedition over the continent nearly
to the coast of California. Harrisse (1900)
ignores the western component of the direction of
"maestrale" and considers only its northerly
meaning. He states that plotting 870 leagues
along the American coast would bring Vespucci's
ships as far north as Cape Hatteras. According
to Vespucci's narrative, the expedition turned
east toward Bermuda from this place and returned
to Cadiz on October 15, 1498.
Humboldt (1836-39) expresses doubt whether
Vespucci ever made this voyage and denies him
the credit of discovery of the new continent.
According to Humboldt, at the time of his sup-
posed voyage Vespucci was engaged in equipping
the third expedition of Columbus and could not
possibly have taken part in the explorations he
describes. Obvious inconsistencies in the text
of Vespucci's informal letters are unfortunately
augmented by errors in translation. The accusa-
tions that Vespucci was a fake (see Winsor 1886,
v. 2, pp. 129-136; Harrisse 1895) are answered,
however, by pro-Vespuccian writers (Varnhagen,
1865, 1869a, 1869b, 1870), and final settlement
of the question awaits further historical research.
Bremer (1940) advances an entirely new theory
that the honor of the discovery of the Gulf of
Mexico belongs to a Portuguese by the name of
Gaspar Corte Viall who, shortly before 1500, sailed
to the west and upon returning to Portugal spread
the news of the existence of a new continent and
islands in the western ocean. In support of his


hypothesis, Bremer mentions a place on the
northern coast of the Gulf of Mexico known by
tradition as Portuguese Field, which he considers
may be a landing place of Portuguese sailors.
The evidence, however, is not convincing.


The progress of early discoveries in the Gulf
may best be followed by studying the maps of this
period. Since the data concerning the location of
new lands were considered by the Spanish Govern-
ment a state secret, maps and reports which the
captains of the ships were requested to submit to
the government immediately upon their return to
Spain were carefully guarded, and all means were
taken to prevent them from falling into the hands
of other European powers. As a consequence of
this policy of secrecy the first maps of the New
World were engraved and published outside Spain
(in Italy, France, and Germany), using data which
were often surreptitiously obtained or smuggled
out of the country. Many of the original docu-
ments, usually drawn on parchment or oxhide,
were lost or destroyed in war and by accidents;
only a few of these valuable documents were
recovered in more recent years after many
The first map of the world summarizing the
discoveries in the western ocean and showing the
Gulf of Mexico was drawn by Juan de la Cosa, the
companion and pilot of Columbus and owner of
the caravel, Santa Maria, which bore the admiral's
flag and was the first ship to reach the New World.
The map embodies the results of seven important
voyages: the three voyages of Columbus in 1492,
1493, and 1498; the first and second voyages of
Vespucci in 1497 and 1498; and the first and
second voyages of Cabot in 1497 and 1498. The
date of the execution of the map is established by
the inscription which reads, "Juan de la Cosa el
fiso en el porto de Santa Maria en afio de: 1500."
The history of this unique historical document
is interesting. After being lost for three centuries,
the map was found in 1832 in a Paris bric-a-brac
shop where it was purchased for a small sum by
Baron de Walckenaer. Its great significance was
pointed out by Humboldt (1836) when in 1832 he
drew public attention to its importance. After
the death of Walckenaer the map was offered for

sale at public auction and was purchased for 420
francs by the Hydrographic Department of the
Spanish Government. Today it hangs in the
Naval Museum of Madrid, listed in the museum
guide book as number 553, with a detailed descrip-
tion and a brief history of this remarkable docu-
ment (Madrid, Museo Naval, 1945).
The original map is drawn on oxhide, 5 feet
9 inches long, cut square at the tail of the hide
where its width is 3 feet 2 inches. The Tropic of
Cancer runs vertically through the middle; the
top corresponds to the extreme west and includes
the Caribbean Sea and the Gulf of Mexico. The
latter area, instead of geographical details, is
occupied by a rectangular drawing representing
St. Christopher bearing the Christ child, a rather
crude imitation of the famous woodcut engraving
of 1423. Originally the map was rich in blue and
gold and illuminated after the fashion of medieval
manuscripts, but today it is torn and faded.
Peter Martyr, who saw it in 1514 in the house of
the Bishop of Burgos, head of the Maritime
Department of the Casa de Contrataci6n, re-
marked on its highly colored beauty.
The photographic reproduction of the Cosa
map available in the Library of Congress is too
blurred and cannot be clearly copied in the text.
The part of the map referring to the Gulf of
Mexico can be seen in figure 3, representing a
copy found in volume 4 of Humboldt's Examen
Critique (1836-39); this part of the map was
redrawn and oriented by Humboldt in the con-
ventional manner.
One of the earliest documents showing certain
details of the New World and a part of the Gulf
of Mexico is Cantino's map of the world. It
represents for the first time what appears to be
the west coast of Florida and the adjacent part
of the Gulf (fig. 4). It was drawn as a large
planisphere on parchment in gold and various
colors. The map derives its name from Alberto
Cantino, Ambassador of the Duke of Ferrara to
the King of Portugal. The original, located in
Biblioteca Estense in Modena, was obtained
by Cantino for 12 ducats and was sent by him
with a letter to Sefior "Duca Hercole" in Lisbon.
In later years the map was used as a screen and
finally was recovered in a damaged condition from
the shop of a pork butcher in Modena and
deposited in the library.
Some cartographers (see Lowery 1912, pp. 5-6)


MAP or TrilE
dAr'rn ait A krw A V.f
i<'lyllrfie/h,'f w


.----- -

., r,, ,4 ,,/A./

FIGURE 3.-Western part of the map of the new discoveries drawn by Juan de la Cosa. Reproduced from a copy in
Humboldt's Examen Critique (1836).




^ ~ a -

d -' /'

* oS Gb^^ 2

FIGURE 4.--Western portion of the Cantino map of the world, 1502. Original without name, date, or title. Reproduced
from a copy in Harrisse's Les Corte-Real 1883.


consider that Cantino was familiar with the
Portuguese voyages to the New World and incor-
porated their discoveries in his drawing. This
subject, as well as the questions whether "Ilha
Ysabella" on the map represents the island of
Cuba or the Crooked Islands group called "Isa-
bella" by Columbus, and whether the peninsula
west of it is Florida, are critically discussed by
Morison (1940).
The Gulf of Mexico is very crudely shown on
the map of the world made by the German carto-
grapher, Waldseemiiller, and printed in 1507 in
St. Die, Lorraine. This map is famous because
for the first time the continent of the New World
is shown with the name "America" attached to
it in honor of the Florentine explorer. The origi-
nal is owned by Franz Joseph II of Liechtenstein.1
Of the many expeditions that sailed to the New
World during the first decade of the sixteenth
century, the more important ones were those
headed by Hojeda, 1499; Niflo and Guerra, 1500;
Pinz6n, 1499-1500; Lepe, 1500; Bastidas, 1500-02;
Hojeda and Vergara, 1502-03; and Cosa, 1504-05.
Results of these ventures materially enlarged the
knowledge of the geography of the eastern part of
the Caribbean area, but its western section, in-
cluding the Gulf of Mexico, remained unexplored.
In 1513 the expedition headed by Ponce de
Le6n made a formal discovery of Florida, the
existence of which was probably known to Spanish
and Portuguese adventurers who visited the land
north of Cuba but left no records of their findings.
On Easter Sunday, March 27 of that year, Ponce
de Le6n with his three ships was in sight of land
not far from the present city of Jacksonville. To
commemorate the holiday the land was named la
Florida. Failing in his attempt to circumnavi-
gate the "island" Ponce de Le6n turned south
and on May 12 of the same year found a chain of
islands which he named las Islas de los Martires
(present Florida Keys), and about a month later
he discovered the Tortugas. In the following
year, 1514, the King of Spain incorporated the
newly discovered land in an administrative re-
gion known as Adelantado de la Isla Bimini e la
Ponce de Le6n was the first explorer who re-
corded the existence of a strong current along the

I In May 1950 the map was offered for sale at an auction in New York City
with the condition that bids should exceed $50,000, but in the last minute
was withdrawn by the owner.

east coast of Florida. He reported that his ships'
while crossing the stream near Cape Canaveral,
frequently were swept by strong current. He
obviously was referring to that part of the Gulf
Stream which at present is known as the Florida
Current (Herrera 1601, 1728; Stommel 1950).
In 1516 Diego Miruelo undertook another ex-
pedition to Florida, and in the following year,
1517, Fernando de C6rdoba and Antonio de Ala-
minos explored the northern and western coasts
of Yucatan. Driven for several days by a severe
storm they finally saw land with a large Indian
town, near Cabo Catoche. The expedition re-
corded many points, bays, and harbors along the
west coast of the Gulf and safely reached the Bay
of Campeche, giving it its present name. Trouble
started, however, near the place called Champo-
ton where C6rdoba and his landing party were
attacked by Indians. In this encounter, C6rdoba
was badly wounded and many of his soldiers were
killed. Alaminos, the principal pilot of the ex-
pedition, decided to take advantage of the pre-
vailing easterly winds and sailed north to Florida
and then turned south toward Cuba. His deci-
sion was a right one. In a few days the ships
crossed the Gulf and returned to Cuba, where
C6rdoba died of his wounds.
Scientific results of the expedition were signifi-
cant. More than 500 miles of the Gulf coast
were mapped; proof was obtained of the existence
of an open channel between the Florida and
YucatAn Peninsulas; and valuable information was
accumulated regarding the prevailing winds, cur-
rents, and depth of water. Alaminos was still
under the impression that YucatAn was an island.
The name Yucatan was taken from the expression
"Uyucatan" which the Spaniards frequently re-
ceived from Indians in reply to their questions,
the meaning of which was "we don't understand
Before his death, C6rdoba appointed his
nephew, Juan de Grijalva, commander of a force
consisting of 4 ships and 250 men. Experienced
Antonio de Alaminos was again the senior pilot
of the expedition which on April 20, 1518, sailed
from the harbor of Matanzas (Cuba) and followed
C6rdoba's former route toward the Cape of Yuca-
tan. Stormy weather drove the expedition far-
ther south along the eastern coast of the peninsula
toward an island called by the Spaniards la Isla
de Santa Cruz but known at present as Isla de


Cozumel. From this point the ships turned north
around the Yucatan Peninsula and on May 26
passed the point reached by the previous expedi-
tion and entered a large bay which was called
Boca de Terminos (Laguna de Terminos on mod-
ern charts). Grijalva thought that he had reached
the end of the Yucatan island which he named La
Isla de Santa Maria de Remedios, the name which
appeared on maps of that time. The expedition
continued along the unknown coast for nearly a
thousand statute miles to a point a short distance
south of the present location of Tampico.
Grijalva's expedition substantially contributed
to our knowledge of Gulf geography. The names
of many familiar places such as Grijalva River,
the bay and river of Tonola, Coatzacoalcos River,
Alvarado River, and many others were established
and their positions indicated on maps. Alaminos
made many astronomical observations between
Yucatin and Tampico. Some of his determina-
tions of latitude-for instance, that of a small
island where the present town of Veracruz is
located-were accurate within 1. He also ob-
served and recorded the currents along the coast
and made soundings and other hydrographical
When the expedition entered the mouth of the
Grijalva River the Spaniards were encountered
by many Indians having gold in their possession.
When asked for the name of the land the metal
came from, the Indians replied, "Mexico." In
this way the Spaniards heard for the first time
the name of the country which played such an
important role in the expansion of Spanish power
in America.
Upon reaching his farthermost point at Panuco,
Grijalva became convinced that he was exploring
the coast of a large continent and not of an island
as he had first believed. Realizing the importance
of this discovery, he dispatched Pedro de Alvarado
on a fast ship to inform Governor Velasquez of
Cuba of his important finding and sailed back fol-
lowing the same route the expedition took from
A new expedition organized by Velasquez in
1519 was in command of Hernando Cort6s with
Antonio de Alaminos again serving as chief pilot.
In May of the same year the expedition sailed
around Cape Catoche, following in general the
route taken previously by Grijalva. This time
the Laguna de Terminos was explored more care-

fully by Captain Escobar who established its
true nature as a shallow, landlocked body of water
not suitable for establishing a colony on its banks.
Antonio de Alaminos, who was sent northward to
Cabo Rojo south of Tampico, discovered a large
river emptying into the Gulf and named it Rio
Grande de PAnuco.
Besides the surveys of the coast from Cape
Catoche to Tampico, Alaminos' principal con-
tribution to the exploration of the Gulf was the
discovery of a free passage between Florida and
Cuba which represented the shortest route for
Spanish vessels carrying silver from Mexico to
In 1519 Francisco de Garay, Governor of Ja-
maica, sponsored an expedition of Don Alonzo
Alvarez de Pineda to explore the northern coast
of the Gulf. Four ships provided by Garay sailed
from Jamaica toward Florida. Believing that
Florida was an island, Pineda followed the west
coast looking for a passage and, not finding it,
turned west along the northern coast of the Gulf.
In the course of his exploration he discovered the
mouth of the Mississippi River which he called
"Rio del Espiritu Santu" and described the body
of water east of the delta as "Mar Pequefia"
or a small sea, the name of the present Mississippi
Sound which persisted on many charts for nearly
two centuries. Pineda noted the physiographical
character of the shoreline, recorded the positions
of dunes, low-lying sandspits, bays, knolls, marshes,
and oyster banks (ostiales) which abounded in the
Mississippi Sound and in the delta of the Missis-
sippi River. He realized that the majestic fresh-
water stream which he ascended for several miles
must originate on a large land area, and other
observations convinced him that he was exploring
the coast of a great continent.
Although the majority of writers agree with
Harrisse (1900) that the river Pineda named
Rio del Espiritu Santu is the present Mississippi
River, there are others who think that the de-
scription of the country given in his reports
does not agree with that of the mouth of the Mis-
sissippi and that Pineda's expedition actually was
in Mobile Bay (Scaife 1892). This question
probably never will be answered with complete
certainty. As a result of his explorations Pineda
produced several new maps showing, with ap-
proximate accuracy, the outlines of the Gulf
coast. Only one of them, bearing the title "Traza


de Costas de Tierra Firme y las Tierras Nuevas,"
was published. The original, dated 1521, is in
the Archivo General de Indias, in Seville, and its
reproduction is given by Navarrette (1837) and
Winsor (1884, v. 2, p. 218).
In 1521 the west coast of Florida was revisited
by Ponce de Le6n, who landed probably in Char-
lotte Harbor where he was seriously wounded in
a battle with Indians. He died within a few
days, after being taken back to Cuba. This
expedition added nothing to the progress of geo-
graphical knowledge of the Gulf.
The next attempt to conquer Florida and ex-
plore the northern part of the Gulf was made by
Phnfilo de Narvaez, who had distinguished himself
in the conquest of Cuba under Velasquez and was
at the head of an expedition sent by the Spanish
Government to compel Cortes to relinquish his
command in Mexico. His defeat and imprison-
ment by Cort6s did not reflect on his reputation,
and upon returning to Spain he obtained from
Charles I a grant to colonize a vast expanse of
land from Florida proper as far west as Rio
On June 17, 1527, five ships under the command
of Narvaez sailed from San Lucas, Spain, with
600 men and officers aboard. One of his com-
panions was Cabeza de Vaca, the treasurer of the
fleet. After leaving the south shore of Cuba in
March 1528, the ships, driven north by strong
winds, found shelter in a large bay which the
Spaniards called Bahia de Santa Cruz. Ac-
cording to the description given by Cabeza de
Vaca, the bay extended from 7 to 8 leagues inland,
had many islands, and presented an excellent
anchorage with a depth of water of about 6
fathoms. IThere is no doubt that it was the
present Tampa Bay.
Misinformed by Indians that the land north of
the bay, known as Apalachee, was rich in gold,
Narvaez marched overland with 300 officers and
men while his ships under the command of Miruelo
followed the northern direction along the coast.
The rendezvous was supposed to be in a bay north
of the point of their departure.
In about 2 months, Narviez's column reached
the village of Apalachee where with great difficulty
the men found only a few bushels of corn. Trying
to establish contact with the ships, Narvaez turned
south and discovered a river, Rio de Magdalena,
as the Spaniards called it, which probably cor-


responds to the present Apalachicola River. Th",
party suffered many hardships in the swamps of;
this region, and many men perished of exhaustion
and disease.
Failing to contact the ships, Narvaez decided
to march west rather than to return to Tampa
Bay. On the shores of a bay, which probably
corresponds to the present St. George Sound and
which was named Bahia de los Caballos, the
Spaniards were compelled to slaughter their last,'
horses to make crude boats of their skins, and
sailed westward. They followed the shoreline,
entering different lagoons (Pensacola, Santa Rosa,
and others). In November they reached a bay
with many islands (probably Chandeleur Sound in
the Mississippi Sound). Since the water was
fresh they realized that they were near the
mouth of a great river which they attempted to
enter, but strong wind and current drove them
into the sea where Narvaez perished in the storm.
His companion, Cabeza de Vaca, found refuge on
a small island 5 leagues long and 2 leagues wide
which he named Isla de Malhado. The place
may be Ship Island, Horn Island, or some other
island in the Mississippi Sound.
Scattered by the storm, most of Narviez's men
perished. With a few men, Cabeza de Vaca
succeeded in landing on the mainland, where for
6 years he lived among the Indians. In 1533 he
gave up hope that any European ship would visit
the coast and with Lope Oviedo decided to march
westward. Encountering a few small streams
they came to the banks of a very large river which
they considered to be Rio del Espiritu Santu
(Mississippi River), and after crossing it marched
for a long time through Texas until they reached
the Bay of California.
In 1536 Cabeza de Vaca returned to Europe
where the results of the unfortunate expedition
became known. Its principal scientific achieve-
ments can be briefly summarized as follows: The
Mississippi River was seen for a second time;
Tampa Bay was more fully explored, and new
names, such as Apalachee Bay, were added to
After waiting in vain for Narvaez at the place of
rendezvous, Miruelo returned with his ships to
Tampa Bay. It is interesting to note that, al-
though he failed to reach the bay at the north
coast of the Gulf where he was supposed to
meet Narvaez, the name of Bahia de Miruelo


appeared for many years on the charts in the place
of the present Apalachee Bay.
Shortly after the tragic end of the Narvaez
expedition, Fernando de Soto, a Spanish captain
and explorer, was preparing for a new adventure.
De Soto acquired a large fortune from the con-
quest of the Inca Empire in Peru in which he
played a prominent role. He obtained from
Charles V a commission as "Adelantado" of the
lands of Florida and Governor of Cuba and
invested his large fortune in a new adventure.
On May 18, 1539, seven ships comprising De
Soto's flotilla carrying 700 soldiers, 200 horses,
mules, supplies, and materials, sailed from Havana.
On May 25 they reached Tampa Bay, known as
Bahia de Espiritu Santu. From Tampa Bay,
De Soto with a large detachment of horsemen
and foot soldiers went by land to Apalache. One
of his companions, Juan de Afiasco, a prominent
seaman, cosmographer, and astronomer was en-
gaged in making scientific observations during this
military expedition. After reaching the land
north of Apalachee, De Soto despatched Afiasco
south to find a harbor. During this travel the
party discovered the bones and other remains of
Narvaez's men, and coming finally to the shores of
the sea discovered a large bay which they called
Bahia de Aute (present Apalachee Bay).
In January 1540, De Soto ordered Captain
Diego Maldenado to sail for 100 leagues along the
coast to take records of all the bays, harbors, and
rivers and to return in 2 months. In the course of
this survey Maldenado found a bay 60 leagues
west of the Bay Aute which he described as the
most beautiful harbor in the world ("un hermosis-
simo puerto"), protected against all winds. He
named it Achusi. The entire harbor was sounded
with great detail, for De Soto wanted to use it as
a rendezvous and a base for his operations. De-
tailed descriptions made by Maldenado leave no
doubt that Achusi corresponds in every respect
to the present Pensacola Bay.
After exploring the east coast of the American
continent as far north as the Savannah River, De
Soto returned to the Gulf and in October 1540
investigated the place called Mavill or Mauvill
which is the present Mobile. His further ex-
plorations lead him inland and westward to the
banks of the Mississippi which he crossed at
Chickasaw Bluffs near the present location of
Memphis, Tennessee.

In 1542 he died and was buried at the bottom of
the Mississippi River. Before his death he ap-
pointed Luis do Moscozo de Alvarado as his
After many vicissitudes the Spaniards, under
the leadership of their new chief, constructed
several boats in which they sailed down the river,
successfully evading the pursuit of Indians.
Upon reaching Gulf waters they turned westward
with the hope of landing somewhere on the
Mexican coast. All navigation instruments were
lost when the Indians burned the Spanish camp
at Mobile, but one astrolabe was saved by Afiasco.
Being a careful and resourceful man, he managed
to make a sea chart from a parchment of deerskin,
and with a forestaff, made from a ruler, and an
astrolabe salvaged from the fire at Mobile, at-
tempted to guide the course of the flotilla. His
worthwhile efforts were so much ridiculed by the
other seamen because Afiasco had never before
embarked on any other maritime expeditions, that
in disgust he threw his instruments, except the
astrolabe, into the sea.
One_day,_hecause of bad weather, the ships
sought refuge in a small cove. While some of the
Spaniards were gathering shellfish along the shore
they found some slabs of black bitumen almost
like tar which the ocean had cast upon the beach.
Garcilaso, who tells this story (Garcilaso de la
Vega, Varner's translation, 1951, p. 601), says,
"This substance must come from some spring
which flows into the sea or which is born in the
sea itself. The slabs weighed 8, 10, 12, and 14
pounds; and they were found in quantity." The
tar-like substance was successfully used by the
Spaniards to repair the leaky vessels, and after
spending a few days on the shore they continued
westward. This is probably the earliest reference
to the finding of asphalt along the Gulf coast.
After many days of sailing along the coast line
Moscozo entered the mouth of the Pdnuco River
and landed in Mexico.2
The discovery of Pensacola Bay, exploration of
the delta of the Mississippi River and of the
northern coast of the Gulf, and the convincing
evidence that the Mississippi was a mighty stream
draining from a large continent, were the principal
scientific contributions of the De Soto expedition.

2 Detailed account of De Soto's expedition can be found in the report of
the U. S. De Soto Commission (1939).


Its unhappy completion marked the end of the
period of the earliest explorations in the Gulf.
Sixteen years after the return of Moscozo a
Spanish conquistador, Don Tristan de Luna,
organized a new expedition to the Gulf. This
expedition contributed little to the science of
geography. By this time Spain's interest in the
new land across the ocean and the enthusiasm of
her rulers for new explorations and colonization
of the New World somewhat slackened.
Although the great advantages derived from
the possession and colonization of the newly dis-
covered territories were fully appreciated by the
Spanish Government and by the educated class
of the Spanish nation, the country lacked ability
and resources to develop them. At the same time,
the Spanish Government jealously watched the
efforts of other nations to establish themselves in
the New World. It tried by every means to
prevent French colonization of the country sur-
rounding the Gulf of Mexico and did not hesitate
to send military expeditions to destroy French
The results of many expeditions in the Gulf
conducted during the first half of the sixteenth
century provided the cartographers with new,
reliable material for the construction of new maps,
and consequently, the outlines of the Gulf shown
by them in their drawings began to assume more
or less correct configuration. This can be noticed,
for instance, by examining figure 5, representing
Mercator's map of 1538, in which for the first
time the name America was applied to the entire
western continent.
It may be of interest at this point to make a
brief survey of the geographical names which were
given to the Gulf of Mexico. No special name for
the Gulf is found on the map of Juan de la Cosa
of 1500 or the Waldseemiiller map of 1507, al-
though in both of them the location of the Gulf is
clearly shown. Cortes, in his despatches, referred
to the Gulf as Mar del Norte, while the names
Golfo de Florida and Golfo de Cortes are found in
the writings of other explorers. The name Sinus
Magnus Antilliarum appears on an old Portuguese
map made in 1558 by Diego Homen (original in
British Museum). Probably the most remarkable
name is that of Mare Cathaynum (Chinese Sea)
which is found on one chart of the middle of the
(copy reproduced in the M6moirs
*ncy, 1832). In 1550 the name

Golfo de Mexico appears for the first time on the
world map the original of which, according to
Kohl, is in the Bodleian Library in Oxford.
Earlier Spanish geographers used, also, the name
of Golfo de Nueva Espafia. Herrera (1728) called
it Ensenada Mexicana and Sefio Mexicano, the
names which persisted in Spanish admiralty charts
until the eighteenth century. The present name,
the Gulf of Mexico, and the corresponding names,
Golphe du Mexique in French and Golfo Mexicano
in Spanish, appear to have been in use since the
middle of the seventeenth century.
During the latter half of the sixteenth century
the French Huguenots, trying to escape religious
persecution in Europe, made many attempts to
establish colonies in Florida. Their efforts were
primarily directed to the east coast of Florida
where the French penetration lead to many bloody
encounters with the Spaniards. Probably the
most significant French contribution to geo-
graphical knowledge of this time was Le Moyne's
map of Florida. Jacques Le Moyne de Morgues
was an artist who accompanied a French expedi-
tion to Florida under-Laudonniere in 1564. His
map shows only a part of the Gulf of Mexico east
of the Mississippi River. Since it is known that
French observations were limited to the east
coast of America between the point south of
St. Augustine and Rio Jordedan (Charleston
Harbor) in the north, the rest of the map was
obviously borrowed from Spanish sources. The
names of many places are corrupted as, for in-
stance, Apalache Bay is indicated as Sinus
Morquel, corrupted from the Bay of Miruelo, and
the Bay of Ponce de Leon (Tampa Bay) is called
Sinus Joannis Ponce. This map, published by
De Bry in 1591 after the death of the artist, was
for 50 years copied by Dutch and French cartog-
raphers but was completely ignored by the
Le Moyne produced, also, a series of extraor-
dinarily interesting drawings depicting the
home life, habits, methods of hunting, and cere-
monies of the Timucua Indians. Excellent repro-
ductions of these illustrations together with a
translation of the Latin text of De Bry were
published in English (Le Moyne, 1564, ed. 1875)
and some of the drawings are reproduced by
Swanton (1946, tables 51, 53-57, 81, 82, 85, 87,
and 106). Examination of these illustrations
gives an insight into the tribal life of Florida



1~ -r'--

I ~


Indians as it was interpreted by a French artist.
Particularly amusing are the scenes of alligator
hunting in which the beast exceeds many times
its normal size and the peaceful scene of the
Timucua Indian women sowing their fields, the
latter drawing conveying a bucolic atmosphere
in conformity with the prevailing artistic taste
of that time.
No significant advance in geographical knowl-
edge of the Gulf was made during the latter part
of the sixteenth and the first half of the seven-
teenth century. In this period Spanish ships
loaded with gold and silver continued to sail from
Mexico to Havana following the northern coast
of the Gulf and passing the delta of the Mississippi
River which was called Cabo de Lodo, or Mud
Cape. The names of the earlier discoverers, such
as Pineda, Narvbez, Ponce de Le6n, De Soto,
and others whose exploits made possible the
relatively safe sailings of these ships, were almost
During the last quarter of the seventeenth cen-
tury -a new era of explorations was initiated by
French adventurers who attempted to reach the
Gulf coast from the north in order to establish
there new colonies. In 1673 two French explorers,
Louis Joliet and Father Marquette, descended
the Mississippi River from Lake Michigan and
voyaged south to the mouth of the Arkansas River.
In 1682 La Salle entered the Mississippi by
way of the Illinois route, explored the river to its
mouth, and in the name of France took possession
of its entire drainage basin. Seeing great political
and economic advantages in establishing a colony
at the mouth of the Mississippi River, he obtained
support of the French Government and in 1684
sailed from Europe with four ships, one of which
was shortly captured by Spaniards. La Salle
missed the mouth of the Mississippi River and
landed farther west in Matagorda Bay, Texas,
where he established his colony. Misfortunes,
disease, and death so devastated the ranks of the
colonists that in a few years only 45 survivors
remained from several hundred who comprised
the original party. In desperation, La Salle
decided to reach Canada by land and during this
journey was assassinated by his men.
One of the results of La Salle's exploration,
which is of definite interest to the geography of
the Gulf, is the sketch map of the location of his
camp on the shores of Matagorda Bay with the

soundings shown in feet. The reproduction of
this map, in the form of a tracing from a photo-
graph of the original, is given by Dunn (1917,
p. 33).
Rumors of the French penetration in the land
bordering the Gulf aroused the half-dormant
rivalry between Spain and France and induced
the Spanish Government to send several military
expeditions with orders to destroy French colonies.
As one of the official documents of that time
stated, it was necessary to "desarraygar esta
espina que se a yntroducido en el corazon del
cuerpo de la America" which means to uproot the
thorn that had been thrust into the heart of
America (Dunn, p. 42).
In 1686 Martin de Echegaray, a naval captain
of the presidio of St. Augustine, Florida, attempted
to interest the Spanish Government in strength-
ening Spanish influence in the domain of Florida
by transporting 50 Spanish families from the
Canary Islands and 25 Indian families from Cam-
peche. In support of his plan, Echegaray sub-
mitted a map, which is a good example of the
defects of the geographical knowledge of that
time, of the interior of the American continent.
The Echegaray map shows the large "river
Canada," or St. Lawrence River emptying into a
lake from which two rivers lead southward to the
Gulf of Mexico, both emptying into Espiritu
Santu Bay (Mississippi River). Echegaray's
scheme was not accepted, but the Spanish Gov-
ernment took other measures to counteract the
French penetration into the new continent and
to destroy La Salle's colony of which they were
afraid. An interesting account of these attempts
is given by Dunn (1917). It is sufficient to men-
tion here that not less than four maritime ex-
peditions were sent by the Spanish Government,
and the whole Gulf of Mexico was examined with
great diligence. One of the important results of
this search for French colonies was the rediscovery
of Pensacola Bay which the Spaniards decided
to occupy. Admiral Pez was placed in command
of an expedition organized for this purpose in 1693.
One of his principal companions was Dr. Carlos
de Siguenza y Gongora, professor of mathematics
in the Royal University of Mexico and chief cos-
mographer of the kingdom. Siguenza kept a
detailed journal of the journey in which he re-
corded his observations. The vessels of the
expedition reached Pensacola Bay on St. Mary's


Day, August 14, 1693, and following their custom,
the Spaniards immediately renamed it "Bahia de
Santa Maria de Galve," the last name being
added to the holy name of the Virgin in honor of
the viceroy of the territory. Siguenza made a
detailed survey of Pensacola Bay and described
its configuration, depth, islands, and rivers. The
expedition proceeded farther east and after some
difficulty entered Mobile Bay, made soundings in
the channel, and found that the depth was only
20 "palmas." As a result of Siguenza's observa-
tions strong recommendations were made to oc-
cupy Pensacola, but a final order for this action
was not issued until 1698.
Rivalry among the western European powers
in establishing a foothold on the shores of the
Gulf of Mexico greatly enhanced the geographical
knowledge of the region. As a military necessity
the whole northern coast of the Gulf, with har-
bors, rivers, and lagoons, was surveyed; fairly
accurate navigational charts were prepared; and
information was accumulated regarding the pre-
vailing winds and currents. In this way marked
progress was attained in the cartography of the
Gulf and adjacent coastal lands.
At the beginning of the eighteenth century
sailing vessels of European powers engaged in
trade or in pursuit of military designs continued
to traverse the waters of the Gulf in ever in-
creasing numbers, but the era of ambitious ex-
peditions and daring adventures, which in the
past fired public enthusiasm, was over. As a
matter of routine the ships made astronomical
observations and determined the longitude and
latitude of the places already known, surveyed
the harbors and passes, made numerous sound-
ings, and recorded the direction and velocities of
winds and currents. These navigational data
were eagerly sought by the cartographers to be
incorporated in new maps, numbers of which ap-
peared in various European countries and in
Mexico. Examples given below, which illustrate
this progress, have been selected from a large
array of the cartographic material issued during
this period.
French interest in the Mississippi River and the
surrounding country is clearly expressed in the
work of the famous French geographer, Guillaume
Delisle (in the French publications the name is

spelled "de L'Isle" and "Del'Isle") whose chart of
Louisiana and of the course of the Mississippi
was composed in 1719. The inscription reads
that it was drawn after consulting many memoirs
of Le Maire and others. The map shows the
routes of De Soto and of other explorers and depicts
the course of the principal rivers. The name
Texas (Los Teijas) for the first time appears in
cartography. According to Kohl (1857, No. 238),
the Delisle map is "the mother and main source
of all the later maps of the Mississippi and of the
whole West of the United States."
The entrances to the Mississippi River, being
of great importance to the French mariners, were
surveyed with great persistency. Among the
many persons who contributed to our knowledge
of the physiography of the river, Lemoyne de
S6rigny occupies a prominent position. In 1719
he participated in military operations in Florida
and Louisiana and led a successful attack from
the sea against Pensacola. His observations
along the northern part of the Gulf coast are
incorporated in a map drawn by an anonymous
French cartographer and entitled "Carte de la
c6te de la Louisiane depuis l'Embouchure du
Mississippi jusqu' A la Baie de St. Joseph, etc."
The Library of Congress has a photographic
reproduction of this document. The original is
in Paris in Dep6t de la Marine. S6rigny produced,
also, a detailed map in colors of the approaches
to Pensacola Bay. The notation on the body of
the latter map contains reference to a strong
surface current and the rise and fall of tides
approximating 3 feet during a 24-hour period.
In connection with the construction of fortifica-
tions around the recently founded city of New
Orleans, the French Government detailed many
engineers to Louisiana. Among them Bernard
de la Harpe distinguished himself by numerous
observations which were incorporated in the de
Beauvilliers map of 1720. The map shows many
streams, mountains, towns, and Indian villages
along the Gulf of Mexico and many islands off
the coast of Yucatan. The chart of the Louisiana
coast drawn about the same time (1719-20) by
Devin was also made on the basis of the reports
of De la Harpe and other French army officers
It shows many soundings and the positions of
shallows and reefs in St. Louis Bay and adjacent
The necessity of having accurate maps for safe


navigation along the coasts of America was fully
recognized in England. Among the many charts
published there during the first half of the
eighteenth century that of Henry Popple, issued
in 1733 on 20 sheets with an index, is of particular
interest. This large chart, measuring 232 by
239 centimeters has the following title: "A Map
of the British Empire in America with the French
and Spanish Settlements adjacent thereto." A
prospectus attached to the first impression con-
tains a detailed description of the map. The
Library of Congress has three impressions, one of
which is imperfect.
About the middle of the eighteenth century
the Spanish Government, feeling the need for
more accurate information regarding the extent
of its dominions in the New World, demanded by
the royal decree of 1741 the submission by local
authorities of detailed suveys of their adminis-
trative districts. Data thus obtained were
summarized by Don Jose Antonio de Villasefior y
Sanchez, Auditor General of the Department of
Quicksilver, who enjoyed a reputation as a
"distinguished mathematician, accurate historian,
and a good citizen" (Bancroft, 1883-86, v. 3, p.
510). The entire undertaking resulted in the map
issued in 1746 under the title, "Icomismo hidro-
terro 6 Mapa Geographico de la America Sep-
tentrional" (original in Arch. Gen. de Indias,
Seville; copy in Library of Congress). In the same
year the Spanish Government detailed Fernando
Consag to explore the upper part of the Gulf
coast. A reproduction of his map is given by
Bancroft (1883-86, v. 1, p. 463).
Jacques Nicolas Bellin, an engineer of the
French navy, was probably the most outstanding
cartographer of the second half of the eighteenth
century. In carrying out official orders of the
French Government he made a detailed survey of
the coast of Louisiana and of the course of the
Mississippi River, drew a plan of Pensacola Bay
(1742), published marine atlases and many maps
(Bellin 1749, 1755, 1764). His map of the Gulf
of Mexico and of the islands of America, issued
in 1754 and published in volume 12 of Pr6vost's
Histoire gen6rale des voyages (1746-89, pp. 8-9),
;*istrates the state of geographical knowledge of
that time. One can see from this map (fig. 6)
that the configuration of the Gulf, especially along
its west coast, is still incorrect, and the shape of
the Florida Peninsula is far from being true.
259534 0-54-3

In this respect, as well as in the manner of drawing
and the angularity of the coastal line, Bellin's
map resembles the one prepared by his predecessor,
Royal Cartographer D'Anville, in 1731 (fig. 7).
Although the outlines of Florida are almost identi-
cal in the two maps, it is interesting to note that
Bellin does not show such a fantastic array of
bays and sounds as are indicated in the southern-
most part of Florida by D'Anville.
One of the most notable documents of the
second half of the eighteenth century is a map of
the British and French dominions in North
America published in London by John Mitchell in
1775 in accordance with the Act of Parliament
(Mitchell 1755, 1757). The original of one of the
earlier issues, identified by only one insert (Hudson
Bay) instead of four in the later editions, can be
found in the library of Harvard University. A
copy of a French edition of 1756 is in the Library
of Congress.
Mitchell's map was first used by American and
British diplomats at the Paris peace conference of
1782-83 after the surrender of Cornwallis at
Yorktown. Since that time it had been referred to
and quoted as an authentic document in many
boundary disputes between the United States and
European countries.
The Harvard University copy has an interesting
quotation from John Adams attached to the map
which reads as follows: "We had before us . a
variety of maps but it was the Mitchell's map
upon which was marked out the whole boundary
lines of the United States." The map shows only
a small section of the northern part of the Gulf of
Mexico between longitudes 8304' and 970 W. and
latitudes 28020' and 30020' N. Tampa Bay is
still called Baia del Espiritu Santo, and there are
interesting notations regarding the depth of the
water "20 feet water over the Bar of Pensacola the
Chief Harbour hereabout" and the depth of "Ye
Missisipi" stated to be "18 feet water into Balise,
12 feet over the Bar, 45 feet within, 50, 60, and 100
In 1764-71 George Gauld ordered by the
British Admiralty to make a survey of the coast
of the provinces of West Florida and Louisiana,
produced a map known as "Admiralty Chart."
He also gave accounts of his surveys of Florida
and sailing directions in the West Indies and
Florida Keys (Gauld 1790, 1796). Several edi-
tions of Gauld's maps were issued in the United

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FIGURE 6.-French chart of the Gulf of Mexico and of the islands of America by Bellin, 1754.
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FIGURE 7.-French chart of the islands of America and adjacent countries by D'Anville, 1731.

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States and in England and can be found in the
Library of Congress.
In 1774 Captain Bernard Romans published a
chart of the coast of East and West Florida to
accompany his book on natural history (Romans
1776). The document is dedicated to the Marine
Society of the City of New York; it is so rare that
its existence was doubted by some bibliographers.
The original is now in the Harvard University
Library, and the map was referred to in Senate
Document, 30th Congress, 1st Session, Report of
Committee No. 242, August 12, 1848, to accom-
pany Bill S. No. 338, relating to the Ever Glades.
Romans' observations are of interest to biologists
on account of the list of higher plants of Florida
collected and identified by him and because of his
remarks concerning the fisheries of Florida and
Georgia. According to his statement, the princi-
pal fishes caught for trade and export were red
drum (called in East Florida "bass" and in West
Florida "carp"), pompano, sole, sea trout, and
mullet. Oil was extracted from the livers
of "nurses" (sic) and sharks, and glue was made
from sea trout by drying them. The product was,
using Romans' expression, "a perfect ichtyocalla."
Although no organized studies of the hydrog-
raphy and oceanography of the Gulf were
conducted during the eighteenth century, infor-
mation received by the admiralties of the European
countries from captains sailing the Gulf waters
provided material for the corrections of the
existing maps.
An interesting translation of a Spanish docu-
ment was published about 1740 in London
(Carranza 1740). The manuscript and the chart
of the West Indies were given Carranza by a
prisoner in Havana as a token of friendship. The
book contains interesting data on tidal currents,
description of shoals along the coasts of Yucatan
and Florida, and depicts the channels that should
be followed in navigation. Chapter 5 deals, in a
rather detailed manner, with the currents and
gives information on the variation of the compass
which, as stated in the text, "is easterly, that is
to say, in that part of it, among the shoals of
Campeche it is 320', and when you are out of
soundings, 430'; in the middle of the bay 5%
to 60 and on the coast of La Vera Cruz, it amounts
to 7."
Incidental biological observations were occa-
sionally reported by seafaring captains. Captain

During (1726, new ed., 1928) mentions, for in-
stance, many sea turtles his crew found on the
shore when his ship was aground in Campeche
Bay. He states that from June to August they
lay eggs of which he counted as many as 150 in a
litter. He found, also, in the same bay a large
herd of "sea cows, or manatees, from 12 to 14
feet long and weighing from 800 to 1,000 pounds,"
about which he writes, "the flesh of it was as white
as the finest veal. Their hides are cut into small
strips to make whips which the poor slaves are
well acquainted with all over West Indies." He
makes numerous references to sand flies and
troublesome "muchetos" infesting the woods.
No biological studies were undertaken, however,
during this period, and no attempts were made to
obtain a representative collection of plants and
animals of the Gulf.


At the beginning of the nineteenth century the
geographical knowledge of the Gulf of Mexico
made marked progress. As can be judged from
the charts of that period the configuration of shore-
line including the coasts of Florida and the Yuca-
tan Peninsula appeared to be almost correctly
outlined; many shoals and banks were shown with
numerous soundings and notations regarding the
character of bottom together with other hydro-
graphical data. The Spanish map of Don Juan
LangAra, issued in 1799 and revised in 1805, is
a good example of the best type of cartographic
material available at this time (issues of this map
are in the Library of Congress and in the American
Geographical Society).
By the middle of the nineteenth century gross
inaccuracies apparent in the older issues were
almost eliminated as can be seen by examining
Laurie's map (fig. 8) published in 1856 in London
or a chart which appeared in a French manual
for navigation in the Caribbean Sea and the
Gulf (Kerhallet 1853). The latter map shows a
general picture of the movement of surface waters,
depicts the ingress of the Antillean Current, and
indicates the existence of a large eddy in the central
part of the Gulf (fig. 9).
In the United States the act of Congress of
February 10, 1807, inaugurated a new era of ma-

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FIGURE 8.-English map of the Gulf of Mexico by Laurie, 1856.
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FIGURE 8.--English map of the Gulf of Mexico by Laurie, 1856.

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FIGURE 9.-French map showing circulation of water, from the Manual of Navigation, by De Kerhallet, 1853.




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rine explorations by authorizing the President to
"cause a survey of the coast of the United States
and to employ proper persons in accomplishing
the purpose prescribed in the act," for which a
sum not exceeding $50,000 was appropriated.
From 1816 to 1843 the reports of the Superin-
tendent of the United States Coast Survey,
made in compliance with this act, contained no
references to the work in the Gulf of Mexico.
Some explorations in the Gulf were conducted,
however, by the United States Navy. In 1839
the U. S. S. Vandalia, under the command of
Uriah B. Levy, was engaged, from February 4
to August 3, in the hydrographic exploration
between Galveston and the southwestern pass of
the Mississippi River.3
The reconnaissance survey of the Gulf coast
was commenced by the United States Coast
Survey in January 1845 (Report of the Super-
intendent for the year ending November 1846),
and since that time the work of the organization,
renamed in 1878 United States Coast and Geodetic
Survey, is being continued at the present time.
A large number of hydrographic and topographic
charts issued during this time show the high degree
of perfection achieved by this agency during more
than a century of continuous work. The years of
different surveys made in various sections of the
Gulf can be found in the Hydrographic Index
Charts, Nos. 80-91, and Topographic Index
Charts, Nos. 20-32, issued by the United States
Coast and Geodetic Survey.
The main features of the Gulf-the configura-
tion of its bottom and the circulation of water and
its emergence as the Gulf Stream-were the ob-
jects of many investigations. The exploration of
the Gulf Stream was commenced in 1844 by Davis
(Report of the Superintendent, U. S. Coast Sur-
vey, year ending November 1846) and was
continued by Bache in 1846, who inaugurated a
series of deep-sea investigations of the physical
problems connected with the Gulf Stream (Bache
1852, 1859). This work was expanded by his
successors in the United States Coast Survey,
Benjamin Price, Carlile P. Patterson, and Julius
E. Hilgard. The results of the Gulf Stream ex-
plorations, including observations of distribution
of water temperatures in the Florida Channel

3 Copy of the chart of the cruise of the Vandalia is in the Library of the
American Geographical Society of New York.

and Straits, were discussed by Bache in several
articles (Bache 1854, 1860).
In 1850, at the request of the United States
Coast Survey, Professor Louis Agassiz undertook
an extended biological survey of Florida reefs and
obtained valuable information concerning the
topography of Florida, the mode of formation of
reefs by cementation, and the origin of the
Florida Keys (L. Agassiz 1880).
Occasional references to bottom animals of the
Gulf are found in French publications of Folin
and Perier (1867-72), in which are described
several new species of mollusks and ostracods
from the bottom deposits collected near Veracruz
and in Laguna de T6rminos.
Maury's (1858) classical book on the physical
geography of the sea contains no specific reference
to the Gulf of Mexico except a brief note con-
cerning the corrosive action of Gulf waters, which
were observed to be more destructive to copper
sheeting of ships than the water from any other
part of the world.
Systematic deep-sea explorations carried out in
1867 and 1868 by Pourtal.s and Mitchel on the
United States Coast Survey ships Corwin and
Bibb consisted in dredging between Florida and
Cuba, at some places at a depth of 850 fathoms.
Many new types discovered in these collections
and the finding of species of corals and echinoderms
which were considered related to an antique fauna
of the Cretaceous period, proved that a study of
bottom organisms thriving along the course of the
Gulf Stream is of great scientific interest (Pour-
tales 1867; L. Agassiz 1852; A. Agassiz 1888,
v. 1, p. 49; Peirce and Patterson 1881).
Explorations along the west coast of Florida
undertaken in 1872 by Commander Howell were
continued in 1875-78 in other parts of the Gulf
under the direction of Lieutenant Commander
Sigsbee aboard the United States Coast Survey
steamer Blake. In the following years the opera-
tions were extended, under the command of
Commander Bartlett, through the Caribbean Sea
and the Straits of Florida. Alexander Agassiz,
in charge of dredging operations of the Blake
expedition, made a geological study of Florida
reefs which had already attracted the attention
of his father, Louis Agassiz, Le Conte, and Hunt
(A. Agassiz 1888, v. 1, pp. 52-92).'
4 The geology of the Gulf of Mexico is discussed in an article by S. A.
Lynch in this book, pp. 67-86.


Three cruises of the Blake, from 1877 to 1880,
represent an outstanding event in the history of
scientific explorations of the Gulf of Mexico. The
expeditions obtained a wealth of information re-
garding the oceanography and biology of the
Gulf, and the two volumes describing the work of
the Blake written by A. Agassiz (1888) until the
present day remain an important source of refer-
ence concerning the bottom fauna, the structure
and origin of coral reefs, and the distribution of
invertebrates and fishes at depths extending to
2,000 fathoms.
Collections obtained by the Blake served as
material for many important publications on
corals, antipatharians, crinoids, and Crustacea
(Pourtales 1870, 1880); echinoderms (A. Agassiz
1863, 1869, 1878, 1883); hydroids (Clarke 1879);
annelids (Ehlers 1879); mollusks (Dall 1880, 1886,
1889), and many others. Numerous papers dealing
with various taxonomic groups gathered by the
expeditions can be found in the first 19 volumes
of the Bulletin of the Museum of Comparative
Zoology at Harvard College. A discussion of the
deep-water fauna of the Gulf Stream was given
by Pourtales (1863-69).
The establishment, in 1871, of the United
States Commission of Fish and Fisheries marked
the beginning of the study of the important
coastal and marine fisheries of the Gulf. With the
building of the 1,000-ton steamer Albatross in 1883,
the first Commissioner of Fisheries, Spencer F.
Baird, initiated worldwide explorations of the sea
fisheries. At the time of her completion, the
Albatross was the best equipped dredger for deep-
sea work in existence. One of her first details was
to explore the bottoms of the Gulf of Mexico.
The instructions given in 1883 by Spencer F.
Baird to the commanding officer, Lieutenant
Commander Z. L. Tanner, read in part as follows:
"In returning (from the Caribbean) by way of
Cape San Antonio it will be well to make a run
into the Gulf of Mexico and spend a short time in
making soundings and dredging therein, for the
purpose of obtaining a general idea of the natural
history and the fisheries of the Gulf, preliminary to
a more lengthened visit to be made hereafter"
(Tanner 1886). The instructions specified that in
addition to the purely physical work, soundings,
temperature, and observation of currents, the
Albatross should secure "a fair representation of
the shore fauna of the Caribbean Sea and its

surroundings including shallow water, to collect
parasites of the larger fish, birds, reptiles, fresh-
water fish, and the various species of mammals as
well as to obtain aboriginal relics in the way of
articles of stone, pottery, etc." Large collections
made by the Albatross and deposited in the
Smithsonian Institution testify that the instruc-
tions were faithfully carried out.
During the first visit to the Gulf in 1884 the
Albatross explored the bottoms around the west-
ern tip of Cuba (fig. 10, open squares) but return-
ing in the following year made more detailed
explorations around Cozumel Island, along the
eastern edge of Campeche Bank, on red-snapper
banks off Cape San Blas in the northeastern part
of the Gulf, and occupied a few stations along the
west coast of Florida and at Key West (fig. 10,
black double circles).
A brief but interesting account of the history
of the Albatross is given by Hedgpeth (1945, 1947).
Simultaneously with the oceanographical stud-
ies the United States Fish Commission conducted
an exploration of the fishery resources of the Gulf
of Mexico. Accounts of this work with reference
to red snappers, shore seine fishery, oysters, and
sponges are given by Stearns (1884, 1887), Collins
(1887), and Stearns and Jordan (1887).
In 1880 the United States Commission of Fish
and Fisheries built a steamer, Fish Hawk, for the
purpose of assisting in fish-hatching operations
and conducting surveys of fishing grounds. From
November 1895 to 1896, under the command of
Lieutenant Franklin Swift, the Fish Hawk sur-
veyed oyster regions of St. Vincent Sound, Apala-
chicola Bay, and St. George Sound, Fla. (Swift,
1897), the work which 20 years later was repeated
with the same ship by Danglade (1917). In 1898
the Fish Hawk was used by the United States
Coast and Geodetic Survey in hydrographic in-
vestigations of the inshore waters of Alabama.
In 1901 and 1902 the ship was engaged in sponge
investigations along the west coast of Florida.
The exploration in 1901 covered the grounds be-
tween Anclote Anchorage, St. Marks, and Tampa
Bay. In the following year the operations ex-
tended along the western coast of Florida, to the
depth of 10 fathoms, from Cedar Keys to Key
West. In 1905 the Fish Hawk was detailed to
survey the oyster bottoms and make hydro-
graphic investigations in Matagorda Bay, Tex.
(Moore 1907), in 1911 made a similar investiga-

Approximate location of
stations occupied by Albatross
S I 1884

bq Mabel Tailor
A-in 1932
bq Blake

0A ft 0 '

-A 6
S> "




4 '


96- 95* 94' 93- 92' 91" 905 89" 886 87- 86- 85 84' 83 82* 81i 80c 79' 78'

FIGURE 10.-Approximate location of stations occupied by the Blake, 1877-80, (black circles); the Albatross, 1884, (open
squares), 1885, (black double circles); and the Mabel Taylor, 1932, (triangles).


tion in Mississippi Sound (Moore 1913a, 1913b),
and in 1913 was used as the base for a survey of
oyster bottoms in Lavaca Bay, Texas (Moore and
Danglade 1915). The completion of the latter
investigation by Moore marked the ending of the
Fish Hawk activities in the Gulf.
In 1917 the research ship Grampus of the United
States Bureau of Fisheries cruised over the con-
tinental shelf from Key West to Aransas Pass in a
study of shrimp and fishery grounds (U. S. Bureau
of Fisheries, 1919).
The results of systematic hydrographic work
conducted by the United States Coast and Geo-
detic Survey and the Hydrographic Office of the
United States Navy with the additional data
accumulated by other explorations served as a
source of material for a general discussion of the
physiography of the Gulf. Forshey (1878) at-
tempted to describe the configuration of the bot-
tom of the Gulf, stressing particularly the deposi-
tion of sediments brought in by the Mississippi
River which he believed eventually will fill up
the Gulf. Lindenkohl (1896) summarized tem-
perature and salinity data taken primarily from
the reports of the United States Coast and Geo-
detic Survey.
In order to obtain basic data on physical ocea-
nography of the Gulf a plan was adopted in July
1905 by the Hydrographic Office of the United
States Navy to supply all vessels crossing the
Gulf with a form for daily use in giving ship's
position, direction and force of the wind, direction
and force of the current, and temperature and
color of the water. The reports of hundreds of
observers extending over a period of years, when
plotted on the monthly charts, agreed remarkably.
The data were summarized by Soley (1914) on a
chart entitled, The Gulf Stream in the Gulf of
Mexico (see Pilot Chart of the North Atlantic
Ocean for June 1914), reproduced in figure 11.
Soley's chart shows the basin of tidal equilibrium
(Sigsbee Deep) more than 2,000 fathoms deep in
the western part of the Gulf, the direction of the
main current, and the Gulf Stream which comes
from the North and South Equatorial Current in
the Yucatan Channel. The Northwestern Branch
of the Current leaves the main stream at the
northeastern corner of Campeche Bank, while the
Eastern Branch turns eastward from the Yucatain
Channel. The chart shows, also, the two counter-
currents, the Cuban and the Western, and the

position of the Central Sea, a circular body of
dead water about 80 miles in diameter. From
the time of the first publication of Soley's chart
basic information given in it is being incorporated
in monthly pilot charts regularly issued by the
Hydrographic Office of the United States Navy
with the additional data supplied by ships and
provided by the United States Weather Bureau
of the Department of Commerce (formerly a part
of the U. S. Dept. of Agriculture).
In January-March 1914 Bigelow (1915), work-
ing on board the United States Coast and Geo-
detic Survey steamer Bache, made observations
in the Straits of Florida studying vertical distri-
bution of temperature and salinity from the sur-
face to the depth of 1,800 meters along the profiles
drawn across the Straits from Key West to Havana,
from Cape Florida to Gun Bay, and from Jupiter
Inlet to the northern end of Little Bahamas Bank.
He noticed the banking up of cold water against
Florida as a result of upwelling from deep layers
on the left side of the channel and concluded that
the cold, comparatively fresh water next to
Florida is largely true abyssal water from the
Gulf of Mexico.
In 1926 the oyster bottoms in the bays along
the coast of Texas were surveyed by Galtsoff
(1931) with special emphasis on salinity distribu-
tion in these bodies of water. From 1936 to 1939
a detailed work on the hydrography of Texas
tidal waters was carried out by Collier (Collier
and Hedgpeth 1950).
The natural history of redfish and other sciae-
nids on the Texas coast was studied by Pearson
(1929) who pointed out the scientific importance
in a study of the biological relationship between
the Gulf and its inland waters.
Marked advance in the knowledge of the hydrog-
raphy of the Gulf was made in 1932 by the Yale
Oceanographic Expedition of the Mabel Taylor
sponsored by the Bingham Oceanographic Founda-
tion. One of the chief problems of the investi-
gation, formulated by the leader of the expedition,
Parr (1935), was to study "the relationship
between the waters in the region of the Straits
(i. e., the area southward between the YucatAn
Channel and the Straits of Florida) and in the
Gulf of Mexico proper." Such a study became
highly desirable in view of Nielsen's (1925)
objections against the purely two-dimensional
picture of surface movements of water in the Gulf




FIGURE 11.-Gulf Stream in the Gulf of Mexico shown by Soley's chart, 1914. The currents as they exist during the different seasons.


of Mexico given in Soley's chart. The expedition
occupied 87 stations (fig. 10, triangles) at which
temperature and salinity of water were recorded
at different levels from surface to a depth of 3,000
meters (1,640 fathoms).5
In 1934 the Atlantis of the Woods Hole Oceano-
graphic Institution occupied, from January to
March, a series of hydrographic stations in
Yucatan Channel and the Straits of Florida, and
in January to May 1937, jointly with the Bingham
Oceanographic Foundation, made observations
in the Caribbean Sea and Gulf of Mexico (Parr
1937a, 1937b). During the cruise of 1947,
sponsored jointly by the Woods Hole Oceano-
graphic Institution and the Geological Society of
America, the Atlantis occupied 551 stations in the
western part of the Gulf between Sigsbee Deep
and the coasts of Louisiana and Texas. In 1951
observations were made by this ship at 240
stations. As a result of this work, combined
with the data obtained by the United States Coast
and Geodetic Survey, a very detailed map of
submarine topography on the northwest quarter
of the Gulf was issued by the Institution in 1951.
In 1951 the Fish and Wildlife Service of the
United States Department of the Interior initiated
a comprehensive research in oceanography and
fishery resources of the Gulf of Mexico. This
work is carried on by the U. S. S. Alaska and the
U. S. S. Oregon, the latter ship being primarily
concerned with the explorations of new fishing
grounds. Material dredged by the Oregon and
deposited in the U. S. National Museum in
Washington proved to be of exceeding interest to
zoologists, for it comprised many rare species
which heretofore were represented only by iso-
lated specimens.
A steady growth of interest in marine biology
in the United States during the last half century
is reflected in an increase in the number of labora-
tories or stations devoted to marine biological
research in general, or to a study of specific
problems of utilization and management of fishery
resources. One of the earliest institutions of that
type in the Gulf was the Gulf Biologic Station
established in 1902 by the State of Louisiana at
the mouth of Calcasieu Pass in Cameron, La.
In 1910, by an act of the General Assembly, the
Gulf station was merged with the State Conser-
5 For the discussion of Parr's work see article by D. F. Leipper, Physical
Oceanography of the Gulf of Mexico in this book, pp. 119-137.

vation Commission, and about 2 years later the
property consisting of 10 acres of land and the
building in which the laboratories were located
reverted to the original donor, Judge Henry,
and the operation of the laboratory ceased.
During its brief existence the Gulf Biologic Station
was concerned primarily with the biology and
cultivation of oysters, scallops, and clams in
Louisiana waters and in studying the distribution
and biology of local marine and brackish-water
plants and animals. The contributions of the
laboratory were published in 15 issues of the
Bulletin of the Gulf Biologic Station issued from
1902 to 1910 and in 3 small biennial reports of
the director dated 1906, 1908, and 1910.6 Brief
data regarding the founding of this station and
its policy are given by Foote (1942).
In June 1904, the Carnegie Institution of
Washington, D. C., established a marine labora-
tory at Loggerhead Key, Dry Tortugas, 68 miles
west of Key West, Fla. The site was chosen
because of the purity of the ocean water surround-
ing the group of seven, small, sandy islands, the
proximity of the Gulf Stream with its abundant
life, the presence of rich coral reefs in Florida,
and the absence of local fisheries which could have
affected the undisturbed life of the sea. Despite
adverse conditions due to the difficulties of regular
communication with the mainland, hurricanes
which frequently swept the Keys, and the short
season of its operation (restricted to 3 summer
months), the station was very productive in
scientific research. Its work inaugurated and
conducted under the inspiring directorship of the
late Dr. Alfred G. Mayer, covered a very broad
field of research in marine biology and general
physiology. The 33 volumes of the Papers from
Tortugas Laboratory contain many fundamental
works dealing with a great variety of problems
such as biology of coral reefs by Mayer, the
physiology of Valonia cells by Osterhout, the
metamorphosis of ascidian larvae by Caswell
Grave, observations on color, habits, and local
distribution of the fishes of Tortugas by W. H.
Longley, ecology and geologic role of mangroves
by H. J. Davis. Many other papers of permanent
scientific value came from the institution, which
more than any other laboratory contributed to
our knowledge of the marine life of the Gulf.
5 I am grateful to Joel W. Hedgpeth for supplying the data regarding the
Gulf Biologic Station.


American scientists interested in marine research
were grieved to learn from the report of the direc-
tor of the Carnegie Institution for 1939 of the
discontinuance of the laboratory due to the
"relatively high cost of its maintenance." At the
time of this action the Laboratory was receiving a
modest annual grant of $12,000 which constituted
about 0.8 percent of the total budget of the
Carnegie Institution of Washington for that year.
Brief mention should be made of the attempt of
the United States Bureau of Fisheries to establish
a fishery laboratory at Key West in 1917. Owing
to the lack of funds for salaries and equipment
the station never became functional and was
abandoned in 1928.
A small laboratory is maintained by Louisiana
State University on Grand Isle. The laboratory
is used every summer from June to July for teach-
ing. Despite modest equipment and lack of
modern research facilities a number of valuable
scientific papers resulted from its operations which
have enhanced our knowledge of the Gulf fauna.
From 1935 to 1937 the United States Bureau
of Fisheries maintained a temporary laboratory
at Indian Pass in Apalachicola Bay, Florida, for
the purpose of studying the biology of the oyster
leech (Stylochus inimicus) and other enemies of
the oyster. Upon completion of this work (Pearse
and Wharton 1938) the laboratory was abandoned
in 1937 and the equipment transferred to the
fisheries laboratory near Pensacola, Fla. The
latter laboratory, established in 1937 primarily
for shellfish research, is located on a small island
in Santa Rosa Sound about 7 miles from Pensacola.
The laboratory, with several auxiliary buildings,
occupies the site of the abandoned quarantine
station. It is equipped with running sea water
and outdoor cement tanks for experiments on
shellfish. The current work consists in ecological
and biological research on oysters in Florida,
Alabama, Mississippi, and Louisiana waters.
The Marine Laboratory of the University of
Miami was established in 1942 at Coral Gables,
Fla., for research and teaching in oceanography,
marine biology, conservation, and management
of fishery resources. Its operations extend over
the waters of the West Indies and the Gulf of
Mexico. The laboratory maintains a station at
Apalachicola for oyster studies and, as circum-
stances require, establishes temporary head-
quarters along the west coast of Florida. Principal

research projects, some of which are sponsored by
the United States Navy, deal with the circulation
of water in the Gulf (Smith, et al., 1951), seasonal
changes in the composition of plankton of Biscayne
Bay and adjacent oceanic waters, red tide, sponge
disease and sponge culture, physiology of fouling
organisms, and many others. Several of the
articles by the members of the laboratory staff
appeared in the newly established Bulletin of Ma-
rine Science of the Gulf and Caribbean and in the
Proceedings of the Gulf and Caribbean Fisheries
Institute founded by the laboratory. The Gulf
and Caribbean Fisheries Institute represents an
effort to integrate the work of oceanographers,
biologists, economists, fishermen, and admin-
istrators. It seems appropriate to point out here
that the idea of preparing a digest of the existing
literature on the biology and oceanography of the
Gulf of Mexico originated at the Second Annual
Session of the Institute and has materialized
through the efforts of several members of this
organization (Walford 1950).
Several other institutions devoted primarily to
the study of Gulf problems, were established in
recent years. The Institute of Marine Science
of the University of Texas in Port Aransas was
founded in 1948 with a grant from the General
Education Board and with funds provided by the
Texas Agricultural and Mechanical Research
Foundation. The Texas Game, Fish, and Oyster
Commission established, in 1949, a marine labora-
tory at Rockport, Tex. The Fish and Wildlife
Service of the United States Department of the
Interior has maintained, since 1949, a temporary
laboratory for red-tide studies at Sarasota, Fla.,
and in 1950 established headquarters with lab-.
oratory facilities at Galveston, Tex., for the con-
duct of oceanographical and biological studies of
the Gulf. The Oceanographic Institute of Florida
State University was established in 1949 with two
seaside stations, one at Alligator Harbor and
another at the mouth of the St. Johns River about
12 miles east of Jacksonville at Mayport, Fla.,
on the Atlantic coast. Research facilities of these
stations, engaged primarily in teaching, are
Since 1947 the State of Mississippi has main-
tained the Gulf Coast Research Laboratory at
Ocean Springs, Miss., for instruction in zoology
and botany.
Recent oil-development activities in the coastal


area of the Gulf provided an opportunity to make
continuous observations from fixed platforms
erected several miles off shore. Analyzing these
records, Geyer (1950) discovered that the salinity
of water of the Louisiana coast at a distance from
5 to 6 miles from the shore undergoes seasonal
variations ranging from 15 to 35 parts per thousand
at 10 feet below the surface. Extensive investiga-
tions of the hydrography of the inshore waters and
the effect of crude oil and brine on aquatic life
have been recently sponsored by the oil com-
panies. Unfortunately, the results of these studies
are not available to the public.
The outlook for scientific investigations of
Gulf problems appears to be bright. There are at
present many laboratory and field facilities
available at various scientific institutions located
along the Gulf coast. Furthermore, Federal and
State organizations show great interest in the
research problems and are in a position to conduct
or sponsor various oceanographic and biological
projects. It is therefore reasonable to expect that
the progress in our knowledge of the Gulf of
Mexico will be rapid and productive.

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By W. ARMSTRONG PRICE,2 Agricultural and Mechanical College of Texas


The scientific study of shorelines is inextricably
involved with that of the hinterland, the coastal
zones, the adjacent inshore waters and the climate.
This linkage brings together regional geology,
geomorphology, sedimentation, oceanography of
the inshore zone, meteorology, climatology, biol-
ogy, chemistry, late geologic history and the
ecology of some marine and coastal organisms.
As the study of shorelines and their classification
is in somewhat incomplete and controversial
condition today, it is necessary to give a brief
review of the subject before discussing the shore-
line of a particular region, such as the Gulf of
Mexico, where there are new types and where we
have previously had few over-all geological
oceanographic conceptions to guide us.

The geological study of shorelines and coasts
has been intermittently developed by numerous
geologists and geographers. The principal dis-
cussions of costal geomorphology that are readily
available are Johnson's (1919) detailed treatise
on shoreline development and his study of the
New England-Acadian shoreline (1925), Shepard's
(1937a, 1948) revision of Johnson's shoreline
classification, Steers' (1946, 1952) analytical de-
scription and history of the shoreline of England,
Wales, and Scotland, and Russell's (1940) study
of the development of variations in deltaic shore-
lines in Louisiana. McCurdy's (1947) discus-
sion of criteria for the delineation of shorelines
from air photographs yields critical details of some
types not found elsewhere. Fleming and Elliott
(1950) have made a beginning of an over-all
quantitative and qualitative oceanographic ap-
proach to the study of shorelines which is here
revised, enlarged and treated in greater detail, in
I Contribution from the Department of Oceanography of the Agricultural
and Mechanical College of Texas, No. 15, April 1953.
2 Professor of Geological Oceanography. Formerly, independent petroleum
geologist of Corpus Christi, Texas.

some of its aspects, for the Gulf of Mexico. Some
of the oceanographic data treated by these
workers have not been considered here.
Among the greatest present needs in geomorphic
coastal studies are a critical analysis and descrip-
tion of the coastal plain shoreline and regional
studies combining the geomorphic and ocean-
ographic approaches. The research on which
this paper is primarily based was a comprehensive
survey of the shorelines of the Gulf from existing
data, including results of the writer's 20-year
study of the northwestern Gulf Coast. The
survey was made by the writer in 1951-1953.3
It has revealed a number of new types and re-
lationships not yet critically discussed in publica-
tion. Because of this situation, the writer is
handicapped in attempting a discussion of the
coasts of the Gulf of Mexico within as condensed
a scope as that of the present paper.
The application of quantitative oceanographic
science to the analysis of the development of shore-
lines is being slowly accomplished through the
work of numerous scientists and engineers by
isolated studies of beaches, cliffs, deltas and
estuaries, but has only lately been attempted for
whole regions. In the writer's current research,
an attempt is being made to apply a quantitative
regional approach to the study of the influence of
oceanographic processes on shorelines and the
associated coastal and shallow-water bottom con-
ditions. Some of the results of this work are
reflected in this paper.
Eduard Suess (1888) showed that regional or
continental shorelines might be classed as con-
cordant or discordant with the grain (dominant
trend) of the geologic structures of a coastal region,
but King (1942, p. 99) cautioned that marine
activities subsequent to the drowning of a coast
or the formation of its folds and faults may have

3 Contains no references to the work of others after March 1, 1953.


.------ ..... --90 ------ ----- 8 -- ----- ,-,'

misP -- RD A---P


+ +--+ ^ +o, + \+ +
^ .i -j^ j.-L ~ i.-. -Li> ^ .~. ^ --^ .-.- r -- ^ ^ --- *' " ** M--------"* .--- ;--- Q


FIGURE 12.-Shorelines of Gulf of Mexico, showing locations of major geographic features. (Contour lines off the
Mississippi delta are drawn at 200-fathom intervals.)


altered the shoreline so that it may no longer con-
form to a simple structural classification. Johnson
(1919) assembled and extended previous ideas
of coastal development and classification to pro-
duce a detailed genetic-geomorphic system that
has since been followed by most writers. How-
ever, it seems not to have been applied by its
users to the detailed mapping of the coasts of a
large, diversified region such as the Gulf of
Mexico, although Johnson (1925) applied it to
the drowned and largely discordant shoreline of
the New England-Acadian region of northeastern
North America.
Shepard (1937a, 1948) modified and extended
Johnson's system, giving a tabulation in which
shoreline and coastal types then described were
inserted. His major divisions differ from John-
son's and seem not to have been accepted by all
of Johnson's followers, although the scarcity of
papers on the classification of shorelines indicates
that this may be due to inertia rather than to a
working appraisal of the usefulness of Shepard's
revised system. Johnson's text is out of print
and has not been supplemented by a similarly
detailed work.
Regional variations in the known physical
oceanographic conditions in the "inshore" zone4 of
the coasts of the United States and Mexico were
discussed by R. H. Fleming and F. E. Elliott
(1950) in lectures. They regarded the scarcity of
such information too great for elaboration of their
method at that time. It, however, classifies coastal
sectors into glacial, alluvial, young orogenic and
biogenous types, with erosional and depositional
sub-types for the first three. The continental
coasts of the Gulf of Mexico were included in the
maps and discussion. The Fleming-Elliott system
has been modified and extended in some of its
aspects for use in the present study as the geo-
oceanographic classification system. Changes in
their mapping of the Gulf coasts include the intro-
duction here of young orogenic sectors and the
relegation of biogenous coasts to a secondary
condition imposed on a framework of regional
geologic and geomorphic types. In the latter
instance, the suggestion made by Shepard (1948,
pp. 78-79) is followed that a regional classification
could be made by using large subdivisions such as
coasts with young mountains, old mountain ranges,

I Shallow water or nearshore zone. Some writers use "inshore" for la-
goonal and estuarine environments.

broad coastal plains, glaciated coasts, and such
specific but less common items as volcanic coasts
and tableland coasts.
Space does not permit including here an elabora-
tion of the detailed genetic-geomorphic classifica-
tion systems. As detailed knowledge of many
coasts accumulates, including coastal plains such
as those of the Gulf, the list of the distinctive
small-unit features becomes encylopedic and the
classification headings numerous, beyond the
simplicity desired (Lucke 1938) for text-book and
lecture purposes.
Definitions.-The shoreline is the line where
land and water meet. It moves back and forth
over the shore or shore zone. The shore on a
beach has been defined (Beach Erosion Board,
Corps of Engineers, U. S. Army) as the zone
between mean low tide (or lower low tide) and the
inner edge of the wave-transported sand. The
lagoonal shore is that of the tidal bays and lagoons.
Estuaries are tidal stream courses. Their shores
are not studied here except where they are em-
bayed. On some coasts there are extensive,
muddy shore-flats. Tidal flats are properly those
within the range of normal gravitational tides.
In some places winds blow the water across broad,
gently sloping wind-tide flats 6 that extend inland
from the true shore, hence, beyond the high tide
limits for gravitational tides, and have been floored
by deposits left by the water.
The coast is a zone of indefinite width back of
the shoreline that is affected by or closely affects
offshore or shoreline processes and forms. The
waters lying near the coast where the effect of a
shallow bottom is felt may be called coastal waters.
The continental shelf (fig. 13) is a submerged, gently
sloping plain that extends the continent ocean-
ward to varying depths ranging, generally, between
40 and 100 fathoms. The shelf is terminated sea-
ward by the steeper shelf slope that descends, in
places precipitously, to the depths. Additional
definitions will be given in later paragraphs when
the barrier island, the shelf and its equilibrium
profile, and the mangrove coastal ridge are
New and undescribed types.-New types recog-
nized on the shorelines of the Gulf of Mexico which
will be readily understood from previous geomor-
phological knowledge are (1) the drowned karst
(sub-aerial limestone solution topography) of parts
5 New term.


of Florida and the Yucatan Peninsula (fig. 12;
fig. 14, sector 2.1); two minor forms: (2) sand dunes
briefly drowned by exceptionally high tides; and
(3) wind-tide flats, previously described. Other
new types that form striking features on the coast
of southern Florida and the Yucatan peninsula,
are (1) the great mangrove barrier ridge (fig. 12;
fig. 14, Sector 4.1); (2) the irregular mangrove
coastal lagoon between the mainland and the
ridge, (3) the drowned lacustrine plain of the Bay
of Florida (fig. 14, Sector 4.1 north of Florida Keys
and east of Cape Sable; fig. 15) as interpreted by the
writer, with former lakes of marsh or swamp now
invaded and enlarged by salt water, and (4) what
the writer believes is the same type of coast slightly
elevated (elevated lacustrine plain) to form the
pocket harbors (Hayes, Vaughan, and Spencer,
1901) of northwestern Cuba (fig. 12; fig. 14, sector
3.1). The present paper does not offer an oppor-
tunity for full critical discussion of these new types.
Besides the distinctly new types of shoreline and
coast, noted here, a number of fairly well known
geomorphic forms were found which have not
previously been included in shoreline classification
lists. Prominent examples for the northwestern
Gulf coast are the broadly to roundly embayed
drowned-stream valley with shallow, pan-shaped
depositional bottom previously described and in-
vestigated by the writer (Price 1947) and the
drowned deltaic topography (fig. 12, betweenBird-
foot delta of Mississippi and Lake Pontchartrain)
described by Russell (1936, figs. 6, 7; 1940).

Published articles include (1) the numerous
detailed geological reports and maps on coastal
land areas in the United States with a few general-
ized and regional reports on those of Mexico and
Cuba, (2) shoreline and coastal studies of the
United States Army Engineers, (3) a few ecolog-
ical studies of coastal areas chiefly in Florida
and Louisiana, (4) progress reports of the ocean-
ographic survey of the Gulf of Mexico being
conducted by the Department of Oceanography
of the Agricultural and Mechanical College
.of Texas (Leipper, p. 125) and progress reports
on investigations of sedimentation and other
shallow water conditions of the northwestern
Most complete for Florida and Louisiana.

Gulf of Mexico by the American Petroleum
Institute and similar commercial projects. Among
scattered reports on previous oceanographic cruises
yielding shoreline or shallow water data (5) is a
study of foraminifera in bottom sediments by
Phleger and Parker (1951). Much geographic
and some geomorphic information is found in
Tamayo's (1949) extensive text and atlas of the
general geography of Mexico.
Important raw data, some of which are listed
in the following paragraph, include (7) topo-
graphic maps and air photographs of the land,
(8) original Federal hydrographic surveys, in-
cluding some old surveys of the British Ad-
miralty, (9) navigation and (10) aeronautical
charts made from these sources, with (11) the
coast pilot and sailing directions handbooks of
these organizations, and (12) bottom-sediment
charts of the shelf of the northern Gulf. Topo-
graphic data are scarce outside the United States
and of unequal detail and coverage for the dif-
ferent States. For Mexico, air photography made
by the United States and Mexican governments is
available under restrictions. The Cuban hydro-
graphic organization has issued a coast pilot
(Derrotero) containing new coast charts.
Charts and other aids in study of coasts.-For any
detailed study of these shorelines it is necessary
to have first, a set of nautical charts. Figure
12, a finding map for this study, is drawn
on the base of the general chart for the Gulf.
The less accurate and detailed these aids are for
any coastal sector, the more they need to be
supplemented by air photography, topographic
maps and geologic reports. The following charts
are recommended.
U. S. Coast and Geodetic Survey Nautical
Charts (U. S. Shores).-General Charts, 1002,
1007, 1290: Sectional Charts 1113-1117; Coast
Charts 1249-1280. For special details, some of
the large-scale charts of islands, harbors and canals,
and Chart A634. See catalog: Serial No. 665.
Hydrographic Office, U. S. Navy, Nautical
Charts (Mexico and Cuba).-General (coastal)
Charts 1125BS, 1126, 1126BS, 2145, 2056, 0966,
5487. See catalog: Pub. I-N.
Marina de Guerra, Departmento de Inspeccion,
Officina Hidrografica, Republica de Cuba.-Der-
rotero de la Isla de Cuba (sailing directions).
Parte Segunda, 1951, 173 pp. 21 figs. has coast


charts from recent surveys done on thin paper,
bound in the book. Soundings and underwater
contours are given to depths of from 30 to 60
brazos de agua (Cuban fathoms).
World Aeronautical Charts, U. S. Air Force
(Mexico and Cuba).-Charts 522, 586-589, and
643-645. See: Aeronautical Chart Catalog,
Coast and Geodetic Survey.
Topographic Maps, Air Photographs and Geo-
logical Reports.-The U. S. Geological Survey
publishes a series of key maps for the United
States, Alaska, and Insular possessions showing
the status of topographic mapping and air (aerial)
photography, including mosaic sheets and with
some geologic mapping. State maps showing
the areas covered by all published geological re-
ports and articles are available for some States
from this agency. The State geological surveys
and bureaus also furnish lists of their publications.
The Geologic Map of North America, Geological
Society of America, 1946, and the American
Geographical Society's Map of North America
are useful regional aids, besides State geologic
and topographic maps.
Areal summaries of oceanographic data.-Since
Vaughan's (1937) survey of information available
in this field no general key maps have been
published. Articles on geological oceanography
of coastal areas are now listed in geological

The writer is indebted to a large number of
persons and organizations too numerous to list
here. Valuable aid was received from the State
geological surveys of Florida and Louisiana, and
some former members of the latter; several mem-
bers of the United States Geological Survey;
officials of the Coast and Geodetic Survey, Hydro-
graphic Office, photographic branches of the
Army, Navy, and Department of Agriculture,
and the corps of Engineers; geologists of the
Mexican federal geological survey and petroleum
development agency, as well as numerous individ-
ual geologists, biologists, ecologists, and other
persons familiar with remote and little-known
parts of the shorelines of Mexico, Florida, and
Louisiana. To his colleagues in the Department
of Oceanography of the Agricultural and Me-
chanical College of Texas, the writer is deeply
indebted for orientation and guidance in oceanog-
raphy during the years of 1950-53, as well as
for specific information and aid. The develop-
ment of the research on which this condensed
paper is based was followed closely by Warren C.
Thompson and Charles C. Bates, while doing
research in the Department, with whom many
helpful discussions have been held. The impetus
in the development of the geo-oceanographic
classification here used, as has been said, came from
the manuscript by R. H. Fleming and F. E.


The Gulf provides a good example of the well-
recognized relation (Weaver 1950) of the
topography of the hinterland to the width of
coastal plains and continental shelves (fig. 13).7
The geologic structure of any hinterland largely
7 Taken from Price (1951 b).

controls its topography and has a direct or indirect
effect (Suess 1888) on the character and positions
of shorelines. These factors are dominant in
determining the drainage and hence, the transport
of sediment from the land to coastal areas.


FIGURE 13.-Major geologic structures exposing uplifted rock masses surrounding Gulf of Mexico. Cross-hatched, folded
sedimentaries, granitic areas, volcanic belts. Stippled, uplifted arches or horsts. Stipple and dash, emerged parts
of arches form limestone plateaus at south and east. Under-water contours, 100 and 1,900 fathoms, the former
out-lining the continental shelf, the latter, the Mexican Basin (Sigsbee Deep). Long broken lines, axes of arcuate
Caribbean folding (axis of Gulf coast geosyncline, supposedly along northwest shore, not yet located. Scale: Hun-
dreds of miles.


Where geologically young mountains (Tertiary
to Quarternary) closely border the coast (Umb-
grove 1947, pl. 5), as in Cuba and the south-
western Gulf coast in Mexico (figs. 12, 13; fig. 14,
Sector 3), coastal plains and the continental shelf
are absent, narrow or of irregular width, and the
shelf tends to be rocky with shoals and irregular
elevations (Fleming and Elliott 1950) as well
as somewhat steep (slope greater than about 5

feet per statute mile). Sand and mud8 occur on
the shelf and mud along the outer margin and in
shelf deeps. The coast may have alternating
narrower erosional and wider depositional sectors,
the latter with smooth shorelines and bottoms,
the former with uneven surfaces. These coasts
and shelves are unstable and subject at any time
to earthquakes, fracturing and warping of the crust.

8 Sediment terminology used is that of the coast charts. "Mud" is a field
term implying no accurate knowledge of the clay fraction.


Young orogenic coasts have their shorelines
dominantly parallel (concordant, Suess 1888)
with the structural trends (folds and faults)
of the mountains. The Gulf provides no ex-
amples of coasts where the shoreline is more
than very locally discordant with the structural
trends on land.9 This accounts to a large extent
for the almost complete lack of islands in the
Gulf other than sandy barriers close to shore,
karst islets of Florida, some lava-rock islets in
Sector 3 in Mexico, and coral and detrital reefs
on shoals. From the meager data of the charts
we conclude that, because the Mexican mountains
are mostly not younger than Miocene, coastal
sediments have built out around or otherwise
protected most of their outpost hard rock folds
from the Gulf. However, a large mountain range
projects eastward under water some 50 miles off
Tampico and two parallel mountain ridges trend
northwestwardly from the edge of the continental
shelf off the Rio Grande delta.
The Tertiary mountains of Cuba (Palmer
1945) rise from a short distance back of the coast.
The folded rocks come down to the coast or are
overlain there by a thin cover of younger deposits.
The island may be divided into several areas of
different tectonic structure, but overthrust folds
rising up to the south dominate some sectors, as
in the extreme west. The Gulf bottom off the
north coast descends at angles of 40 to 60 or more,
a slope which conforms fairly well to some of the
folds. A narrow shelf occurs only where fringing
reefs have grown up with a rising sea level to form
barrier reefs, so that the lagoon has been filled to
a shallow depth with sediment and organic growths
(3.2 Sectors, fig. 14).
The drainage of northwestern Cuba is largely
southward, so that only small streams enter the
Gulf and the coralline lagoons. The sedimenta-
tion along the northwest shore has, therefore,
been negligible except where coral reefs and
mangrove growth have trapped marine and land-
derived materials. An erosional sector occurs
between the barrier reefs east and west of Havana.
The Sierra Madre Oriental, the eastern cordil-
lera of Mexico, slants southeastward toward the
coast, one of the outpost folds in limestone rock
making a minor protuberance at Punta Jerez

9 Discordant coasts are found today chiefly where old mountain areas, as
from New England to Newfoundland, have been drowned by sinking of
coasts under load of Pleistocene ice sheets.

(fig 13).10 The coastal plain becomes gradually
narrower southward from the delta of Rio Grande.
It is, however, as much as 60 or more miles wide
in places.
The Southern Volcanic Range of Mexico
(Sierra Neo-Volcanica, Tamayo 1949), a zone
of Tertiary-to-Recent volcanic peaks, runs from
the Pacific coast due east through Mexico City
to form the broadly protuberant Jalapa Salient
north of Veracruz at 200 N. Lat. A similar
salient south of the city, that of San Martin
Tuxtla, separated from the range, may be geo-
logically associated with it. The range includes
some of the greatest peaks of Mexico, including at
the east, in sight of the Gulf, Orizaba and Cofre
de Perote, reaching elevations of 18,696 and 14,048
feet, respectively, above sea. Between and on
each side of these salients are sedimentary embay-
ments (fig. 14, 3.2) with fairly broad coastal plains.
Only a narrow belt of low shoreline deposits
seems to be present along the fronts of the vol-
canic salients. These salients are composed of
confluent and overlapping flows of volcanic rocks,
some of which make small jutting points at the
shoreline. Of these, Roca Partida and Punta
Delgada have cliffed faces reported to be 1,000
feet high, with islets of lava rock.
There are several volcanic peaks in the San
Martin salient, including San Martin Tuxtla,
which has been active in historic time. On air
photographs of this sector, the writer counted
some 20 small cinder cones aligned in a zone about
10 miles wide and 40 miles long parallel with the
coast. One of the cones stands in the
intermountain Lake Catemaco with its crater
invaded by the water.
The continental shelf off the orogenic coast of
Mexico is poorly mapped. It is narrow and,
where mapped, the gradient is convex, becoming
steep, like that near the outer edge of the shelf
of Texas and Louisiana. The grain sizes of the
sediments, so far as is revealed by the data on
the charts, decrease more regularly outward than
on some better-known orogenic coasts, as that
of California where there are separate offshore
sedimentary basins both on and off the shelf,
each with its own sedimentary distributional
pattern. The small size of the sub-aerial drainage
basins where mountains stand near the coast has
o0 The convexity here is exaggerated on H. 0. Chart 2056 as compared
with the later W. A. C. 589, made from a photographic base.


FIGURE 14.-Regional geo-oceanographic classification, shorelines and coasts, Gulf of Mexico: 1, alluvial coasts; 2, drowned
limestone plateaus; 3, young orogenic coasts; 4, biogenous (organic) development on various coasts. Sub-sectors:
1.1, deltaic coasts, with 1.11, unentrenched simple deltaic plain, and 1.12, entrenched and embayed compound deltaic
plain. 1.2, terraced deltaic coastal plain; 2.1, unsimplified to little simplified drowned karst; 2.2, limestone karst with
beaches; 3.1, erosional, and 3.2, depositional, orogenic coasts; 4.1, broad shelf; 4.2 shelf absent to narrow; 4.3 lesser
biogenous development (more extensive than shown). The two southerly Mexican 3.1 Sectors are volcanic salients.

been shown to restrict coastal sedimentation.
This is true here, in that the shelf is wide off the
several sedimentary salients, but narrow in front
of the coastal mountain salients.

Where the closest mountains, usually old
mountains, are located far or moderately far in-
land (Umbgrove 1947, pl. 5), the runoff and sedi-
ment load from the lands has been large and long
continued, interior plains are succeeded by broad
coastal plains and continental shelves, and the

coast is of the deltaic (Fleming and Elliott 1950)
or alluvial coastal plain type. On such a coast,
after sufficiently long stillstand, shelf bottoms
are smooth except toward their outer margins,
organic reefs are inconspicuous, few or absent,
and shorelines are smooth or irregularly deltaic
(fig. 13, and No. 1 Sectors, fig. 14). Sediments here
are generally of even distribution to somewhat
spotty (Lynch, fig. 16). Sands extend from shore
out to about 5 or 10 fathoms, followed by silt or
sand and mud (charts), with mud further out to
the edge of the continental shelf. Mud or silt


may come in very close to the mouth of a deltaic
river that drains a large basin. The chief excep-
tions to the outward banding of sediments (Emery
1952) are any coarse sediments of local organic
or chemical origin, or, along the northwestern
shelf of the Gulf, sediments on mounds believed
to lie above buried intrusive salt dunes (Shepard
1937 b).
The alluvial sectors of the Gulf of Mexico (Sec-
tors Nos. 1.11, 1.12, and 1.2, fig. 14) have smooth
shorelines with sandy beaches on the mainland,
or on barrier islands (Price 1951 a). The beaches
may be more or less interrupted by deltas of vary-
ing degrees of protuberance and shoreline irregu-
larity (Russell 1940; Bates 1953). Offshore, the
alluvial sectors have broad, smooth continental
shelves, 130 miles wide at the maximum, with
relatively steep inshore shelf-bottom profiles (fig.
15, Sector VII) and a rather uniform gradation of
sediment from sand (generally inside the 5- or 10-
fathom depth contour) to sand-and-mud, with
mud at the outer margins. The elevated mounds
on some outer parts of the northwestern shelf have
nodular algal limestone on their tops and possibly
some coral.
Subsectors, alluvial coast: terraced detaic plain.-
Sector 1.2, Alabama. Mississippi, and western
Florida (fig. 14), has a fairly steep coastal plain,"
with two Pleistocene-and-Recent deltas (Apala-
chicola, Pascagoula, and Pearl), a minor amount
of embayment of drowned stream valleys and a
reported series of low, parallel elevated shoreline
scarps (Carlston 1950). In places, the younger
two of these have roughly parallel Pleistocene
bu-irier islands and coastal lagoons (MacNeil 1950)
in part entrenched by drainage and embayed.
This coast is like that of the southern Atlantic
coastal plain of the United States, with which it
has a common geologic history. These similari-
ties exist because of the position of the old (Pale-
ozic), almost entirely quiescent Appalachian
mountains fairly close (90 to 150 miles) to the
coast but not in a bordering position. Drainage
basins extending from the mountain front across
the coastal plain are small in relation to those of
the deltaic 1.12 alluvial coast. The large cuspate
Pleistocene-Recent Apalachicola delta and the
long, broad, and shallow Mobile Bay are striking
features of this coast

11 Eight feet per mile near the coast in some places.

Broadly embayed deltaic coastal plain.-Sector
1.12 (fig. 14), the coast of Louisiana, Texas, and
part of Tamaulipas, receives the drainage of some
ten major rivers. Three major Recent deltas now
reach the Gulf; the Mississippi-Red, Brazos-
Colorado, and Rio Grande deltas. A very broad,
gently sloping deltaic coastal plain (Barton 1930)
has been built, forming a fully concordant coast
(Suess 1888). Coastal plain deposits form a new
structural (monoclinal) trend in front of the abrupt
southwestern ends of Appalachian folds once
projected into the broad Mississippi embayment.
Sector 1.12 (fig. 14) is deltaic except between
arcuate delta fronts where the active barrier and
the Pleistocene Ingleside barrier island (Price
1933) with their parallel, active and entrenched
coastal lagoons form a diversified inner coast tran-
sected by many broadly drowned and embayed
stream valleys (Price 1947). There are, thus,
intermittent terraced riverine plains between ad-
jacent protuberant Recent deltas. Behind the
terraced belt are continuously overlapping and
coalescing Pleistocene deltas with their surfaces
slightly up-warped inland. The great protuber-
ant Mississippi-Red delta (Russell 1936; 1940;
Bates 1953) dominates the eastern part of this
sector both at the shoreline and on the shelf where
large shoals seem to indicate submerged deltas.
A minor feature of the deltaic coast is the saline
marsh (paralic) environment described on a later
page with the biogenous environments.
Saline plain of Rio Grande delta.-A broad,
treeless, saline plain, the Jackass Prairie of
Cameron County, dominated in the native state
by coarse, bunchy Spartina salt grass (sacahuista),
stretches inland across the Recent delta north of
the natural levees of the present Rio Grande
course for a maximum distance of 10 miles. The
Gulfward edge of the plain is honeycombed by
saline lagoons lined on their lee (N., NW., W.,
and SW.) sides by clay dunes (Coffey 1909, Price
1933, Huffman and Price 1949). The soil of the
low deltaic plain is made heavily saline by wind-
blown (cyclic) salt contained in clay pellets and
dust blown from the saline tidal flats of the la-
goons. These flats undergo strong deflation dur-
ing the warm months. Sand-sized pellets of
flocculated saline clay accumulate on lee shores
to build the dunes, while saline dust passes over
the 30-foot-high dunes under the strong steady
hot winds of the warm months.


From detailed topographic data it is estimated
that about one-fifth of the wind-blown clay ex-
cavated from playa lake basins is caught on the
dunes as sand-sized pellets and the remainder
passes inland as dust. The saline plain is nar-
rower in Willacy County to the north where the
Recent delta and the zone of playas and dunes is
narrower than to the south near the Rio Grande.
Unentrenched deltaic sector.-Sector 1.11, the
coast of Tabasco and parts of Veracruz and Cam-
peche, Mexico (figs. 12, 14), is a simple deltaic
coast with a tropical rain-forest and fairly wide
tidal streams that are not embayed. The large
Laguna de Terminos is a delta-margin depression,
a feature which Bates (1953) thinks is normally a
nondepositional basin. Sinking by compaction,
former entrenchment and enlargement by wave
and current scour are factors that aid in shaping
some of the delta-margin basins. This sector has
a broad, gentle deltaic plain, abundantly crossed
by innumerable courses of the Tonala, Seco,
Grijalva, Teapao, Usumacinta, San Pedro Y San
Pablo, and Palizada Rivers. These courses are
grouped into two main deltas; the Seco-Grijalva
delta at the west, with a broadly and symmetrically
bowed shoreline, and the asymmetrically bowed
Grijalva-San Pedro Y San Pablo delta at the east.
The latter has a small cuspate mouth.

Continental or insular shelves may exist off the
above-water parts of oceanic shoals appearing as
island groups or as peninsulas attached to con-
tinents. Very broad shelves, upwards of 100 miles
wide, border the peninsulas of Florida and Yuca-
tan in the Gulf (fig. 13 and No. 2 Sectors, fig. 14).
These low peninsulas are great uplifted limestone
shoals, now partly drowned limestone plateaus.
Their origins have been discussed elsewhere (Price
1951b). The surfaces of these plateaus, both
above and below water, show a young rolling
karst topography of limestone solution with
solution-basins and sinkholes. Surface drainage
is locally absent and is supplemented by under-
ground water circulation moving through solution
channels. The Florida limestone is abundantly
fissured, at least at the northwest (Vernon 1951).
The plateau peninsulas are terraced limestone
coastal plains. They have delivered a minimum
of land-derived detrital sediment to the shelves,

so that, under tropical climates, these shelves
in places abound and probably have long so
abounded in great coral reefs (F. G. W. Smith,
p. 291) and some reef-like bars and sand keys
of shell detritus.
The sinkhole topography of the limestone
plateaus is of subaerial origin, now modified in a
broad belt near the shoreline, both above and
below water, by coastal deposits (Vernon 1951)"
and an undetermined amount of solutional activ-
ity (Fairbridge 1948). There are a few relatively
narrow, submerged stream valleys. Submerged
subaerial karst basins are, so far as known, only
shallowly filled with a foot or two of sediment,
yielding poor anchorage for ships. Offshore bot-
tom slopes of the inner half or more of the conti-
nental shelf are very gentle (fig. 15, curve 6) to
moderately gentle (fig. 15, curve 4), ranging from
about 1.5 to 2.5 feet per statute mile. For a few
miles offshore, there are many, irregular, shifting
bars of shelly sand.
The limestone-plateau coasts have three types
of subsectors: slightly elevated drowned karst
salients of a low marshy coast (2.1), beach-bor-
dered (2.2), and mangrove-ridge (4.1) shorelines.
These show shoreline modification and smoothing
ranging from a virtual zero modification through
incipient planation to nearly completely smooth
beach-bordered coasts. Coastal marsh and swamp
of the limestone plateaus are abundantly chan-
neled perpendicular to the shoreline by tidal
scour. The tides are higher on the peninsula
coast of Florida (range 2 to 4.5 feet) than on any
other part of the Gulf shoreline. Inshore on the
drowned karst coast, and offshore on it and on
the other subsectors of the limestone plateaus,
we have the so-called carbonate environment of
the continental shelf (Trask 1937).
Subsector 2.1 (fig. 14), along the northern coast
of peninsular Florida north of Anclote Keys, near
Tampa, has a new type, the drowned karst shore-
line. Short convex areas have an intricate, cren-
ulate shoreline with many small shoreline basins
and archipelagoes of stony islets. Much of this
karst shows, on the scale of the navigation charts,
no modification by marine agencies. This entire
subsector lacks embayed drowned stream valleys
12 Zones of submerged bars and their uplifted counterparts on elevated


and sandy beaches (Martens 1931) except short,
elevated stormbeach ridges and sandy beaches on
some of the Cedar Keys archipelago at 29010' N.
Lat. These latter beaches (Martens 1931) are
somewhat muddy and unlike those of glaringly
white sand on the front of the Apalachicola delta,
Sector 1.2, and westward from it in Florida.
With this drowned karst coast of Sector 2.1,
there are areas of transversely channeled marsh 2
to 3 miles wide occupied by grassy vegetation and
forested swamp. This swamp is probably mostly
saline. Patches of mangrove swamp occur in the
southern part of this Sector.
The scattered mangrove swamps with offshore
oyster reefs to be described mark a minor exten-
sion of the biogenous environment (Sector 4, fig.
The drowned karst coast is conspicuous for its
many and unique marine oyster reefs, located
along a shallow-water zone extending outward to
a distance of a mile or two from shore. Crassos-
trea virginica, the North American oyster of
commerce, is notably lagoonal and estuarine,
commonly being confined to brackish water en-
vironments by its marine-water foes. Only along
parts of the Gulf coast are living reefs of this
species known in oceanic waters in North America.
On Sector 2.1, the highly fractured and channeled
limestones of Florida are filled inland with fresh
water to a considerable height above sea level.
The slope of the groundwater surface (piezomet-
ric) toward the coast indicates a movement of
underground water in that direction. Also, along
much of the coast of Sector 2.1 there is an artesian
groundwater head of about 10 feet near and at
the shoreline (Cooper and Stringfield 1950, fig.
14). This pressure-head forms springs in the
stream mouths and stream beds, as well as
offshore.13 The absence of land-derived sedi-
ment in these streams during most of the year
and the protected nature of the shelf waters leave
the water of the Gulf brackish here. Off the
mouth of Atchafalaya Bay, Louisiana, oyster
reefs also grow in the Gulf out to a distance of
3 to 5 miles, with the fresh water of the river
mixing with Gulf water to produce a brackish
Beach-bordered karst subsector.-Sector 2.2 (fig.
14) is represented both on the central coast of

1" Data on charts and reports of aviators via V. T. Stringfleld, letter of 1952.

peninsular Florida and on the coast of the YucatAn
Peninsula. On Florida, the sector has fairly
continuous sandy barrier islands and barrier spits
with some mainland beaches. This sector ex-
tends from Anclote Keys near Tampa at the north
to Cape Romano at the south. The drowned
karst lies behind the beaches and the coastal
lagoons of the sandy barriers. The lagoons are
bordered by mangrove swamp and with the karst
depressions more or less filled with sediment and
marshy growths.
The beaches of this sector (Martens 1931)
have much shell material but also quartz sand.
The quartz is derived from elevated sandy
Pleistocene beach deposits of the elongated
dome-shaped summit (300 feet or more) of the
peninsula, which lies immediately inland, and from
a sandy limestone formation that has been almost
removed by embayment of several streams to
form the broadly embayed harbors of Tampa
Bay and Charlotte Harbor. These harbors are
the only embayed, drowned, stream valleys of
the Gulf coast of the peninsula, except the mod-
erately widened tidal portion of Caloosahatchee
River, nearby. The shelf-bottom slopes more
steeply off this sector (2.2 feet per mile, fig. 15,
curve 4) than it does farther north on Sector 2.1.
Cape Sable (fig. 12) protrudes into the Gulf
where Florida Bay extends eastward at the end
of the mainland of the peninsula. This major
shoreline bend produces a convergence zone for
waves, swell and currents with the local wave
attack necessary to develop a beach, keeping the
shore free of mangroves. The beach plain has
cuspate points and encloses narrow lagoons
behind it. The beach sand is presumably mainly
The oval area of plain behind the sandy beaches
and the lagoons of the Cape is somewhat marshy.
The origin of the broad, irregular lagoon known as
Whitewater Bay, lying several miles inland from
the beach is linked with the delivery of a concen-
tration of drainage to a marsh. The bay is
heavily fringed with mangrove swamp.
The beach-bordered subsectors (2.2) on the
Yucatan Peninsula include the northern coast
and the short Campeche-Champoton sector at
the west. The northern coast has barrier islands
and a number of slightly disconnected barrier
spits which extend westward from moderate pro-
jections of the shoreline. Pinnacles of limestone


several feet high protrude through the beach in
places (Sapper 1937). Marshy, swampy, and
partly mud-filled coastal lagoons lie behind the
barriers. They are extensively occupied by man-
grove swamp forest. These lagoons are called
"rivers" on some maps. They were formerly
thought to form a continuous inner waterway
across the north end of the Peninsula.
The short beach-bearing sector in the Campeche
coast between the towns of Campeche and
Champton (fig. 12), seems from air photographs
and ground-elevation figures (20 feet to the north
against 400 to 500 feet in the block) to be an
uplifted fault block of limestone with entrenched
stream valleys floored by narrow alluvial plains.
The Gulf ends of these alluvial deposits have
sandy-to-cobbly pocket beaches. Observers re-
port seeing large blocks of limestone on some of
them. One report, probably, erroneous, calls
some of these blocks and a nearby outcrop
"igneous" rock.
Where, on the coasts of the Gulf, land-derived
sediments have been and are now scarce, sediments
of organic origin with large marine organic struc-
tures become conspicuous. Such a biogenous
environment (fig. 14, Sector 4) (Fleming and
Elliott 1950) may vary, here and there, from a
brackish lagoonal and inshore environment to a
marine environment with waters of normal salinity
or salinities somewhat above average (Trask
1937). Where the water is now, or has lately been,
warm, tropical and of at least normal marine
salinity, coral reefs thrive. The physical limita-
tions of this environment have been long and
widely discussed.
The biogenous environment is an oceano-
graphic condition existing as an overlay on the
basic geological coastal structures. It may occur
on any type of shoreline where, and so long as,
the requisite sedimentary and oceanographic
conditions previously mentioned occur. The biog-
enous environment includes the carbonate en-
vironment, where Mollusca and corals are con-
spicuous among the sedentary organisms, and the
paralic or marine swamp and marsh environ-
ments, such as those of the mangrove and salt-
water grasses and reeds.
It may be that, with further analysis, a funda-
mental geological coastal type of biogenous

nature may be recognized. Thus, the limestone
peninsulas of Florida and Yucatan may, from the
historical point of view, be considered geologically
biogenous, since the limestones have been built
up for millions of years under dominantly cal-
careous biogenous conditions. The Cuban coast,
and the Gulf coast of Mexico west of the Yucatan
Peninsula, are today only superficially biogenous,
as the organic growths and sediments form a mere
patchwork skin on the rock folds. Limestone
series several thousands of feet thick among the
folded and faulted rocks of Cuba, however, show
that the site of the island was biogenous for
millions of years. Deposits of argillaceous clayeyy)
shales and the great earth-deforming (tectonic)
events, were major interruptions in the carbonate
type of biogenous environment in Cuba. The
structural conditions of Cuba today overshadow,
for geologists, the biogenous history.
Carbonate subdivisional environment.-Subsec-
tors of the biogenous coasts (Sectors 4) present
a variety of structures and bottom types. Coral
reefs and the carbonate environment in general
occur on both broad (fig. 14, 4.1) and narrow (4.2)
shelves. Large shelf areas have a conspicuous
bottom-dwelling population. Among these,
sponges are conspicuous. Actively growing coral
reefs (Smith, p. 292) include fringing and barrier
reefs on Cuba and a barrier reef along the outer
side of the Florida Keys. This coral barrier runs
along the edge of the shelf facing the Straits of
Florida at the far southern end of the peninsula.
Fringing reefs are also found here and there on
other coastal sectors, as near the mouths of
streams on the Mexican coast (Sectors 1.11, 3.1,
3.2) and on 4.1 on the Yucatan Peninsula. The
great Colorados Barrier Reef of northwestern Cuba
is fringing at its eastern end but encloses a 15-mile-
wide lagoon to the west.
Atolls and atoll-like coral reefs of more or less
tabular form occur west of the Florida Keys
(Dry Tortugas atoll) and others form a great, dis-
continuous, barrier range along the northern and
northwestern margins of the Yucat6n shelf, called
the Campeche Banks (Smith, fig. 62, p. 292). The
best known of these is the large Alacran atoll.
The Marquesas detrital atoll off Florida (Vaughan
1914; Cooke 1939, fig. 31) is not known to have
coralline growth, the reef being a group of sand
keys of shell detritus formed on the shelf by the
strong westward currents and winds. The Mar-


quesas is a great lunate key partly closed at the
southwest by a series of smaller lunate keys curved
oppositely to the major key and built by sec-
ondary currents from the west-southwest. The
living barrier reef of southern Florida in front of
the main Florida Keys stands in about 5 to 7
fathoms of water. The Colorados Barrier Reef of
western Cuba stands in about 5 to 6 fathoms.
The barrier range off northern YucatAn, however,
stands in 20 to 30 fathoms, nearer to the edge of
the shelf than to the mainland.
The Florida Keys are partly coralline, partly
of other origin (Cooke 1945, pl. 1, and 1939, pp.
68-72). The main eastern Key range is con-
sidered to be a former barrier coral reef of the
elevated Pleistocene Pamlico (25-foot) shoreline,
now emerged and dead. Its highest present
natural ground elevations are said to be about 18
feet above present mean sea level. This Key
range ends to the southwest in the Boot, Mara-
thon, and Vaca group of Keys. Westward along
the line of the Keys, there is a large emergence of
the Miami oolite limestone stratum to the present
intertidal zone, somewhat built up, in places, by
mangrove peat and marl. Marine carbonate and
paralic deposits combine to form the Pine Island
group of Keys. This low island mass has been
broadly and abundantly channeled in a northwest-
southeast direction by the strong tidal currents
produced by the regularly recurring tidal differ-
ence of 2 to 3 feet between the Gulf and Florida
Straits. Key West is the western terminus of
this group of channeled-shoal Keys.
West of Key West and the Pine Islands lie the
small Sand Keys (Davis 1942) where the main
Miami oolite shoal lies below or mainly below low
tide. These Sand Keys only sparingly fill the gap
between the Pine Island Keys and the large Mar-
quesas atoll.
Scattered coral patches.-The scattered patches
of coral growth mapped by various agencies and
persons along the northern coast of the Gulf
(fig. 14, Sector 4.3), far out on the shelf are not well
known. These notations may refer to growths
on the tops of small salt-dome-like seamounts
found along the edge of the shelf here. Studies
by H. C. Stetson show that nodular algal lime-
stone balls are common on the tops of some of these
small seamounts. Specimens of solitary corals,
possibly from the sea areas, are found sparingly
upon the beaches. Coral patches occur widely
259534 0-54--5

as bottom growths off the central peninsula coast
of Florida.
Paralic, or marine marsh and swamp subdivisional
environment.-In the biogenous environment, as
here defined, grassy to reedy marsh is dominant
between the convex areas of drowned karst shore-
line (fig. 14, Sector 2.1). It is also scattered among
the mangrove swamps. The mangrove swamp
forests (Davis 1940, 1942) form a conspicuous
marginal coastal belt on the inshore sectors noted
(4.1, fig. 14), and occur prominently in the lagoonal
habitat on 4.1 and 4.2 Sectors.
Fresh-water marsh (paludal environment) has
some of its most extensive known developments
on the broad, very gently sloping coastal plain
of southern Florida inland from the marine man-
grove shoreline. The paludal areas include the
famous Everglades and the almost as well known
Big Cypress Swamp.
Marine marshes (paralic) are conspicuous in
places in a relatively narrow zone along the coast
of Louisiana in the deltaic alluvial environment.
Here salt grasses (Spartina) and reeds have
pioneered on deltaic and other shoals. Garden
Island Bay, between two mouths of the Mis-
sissippi's active bird-foot delta, is reported (Russell
1936) to have extended its shoreline materially
by the aid of paralic vegetation. Here, again,
extensive fresh-water marshes lie inland in a
very gently sloping coast from the more notable
saline marshes. On the steeper deltaic coast of
the western Gulf, shore and coastal marsh are
narrow and relatively inconspicuous.
Mangrove swamp growth.-Charts of the near-
tropical coast of Florida (4.1, fig. 14) south of
Cape Romano (1113, 1253, 1254) and north of
the Bay of Florida, and air photographs of a part
of the west coast of the Yucatan Peninsula (4.1),
show a broad, belted disposition of saline man-
grove swamp forest with an irregular brackish
lagoon or line of lagoons landward from it. This
arrangement seems to be unique for North America
and for those parts of the Antilles which have been
studied by the writer. It depends upon the
presence of a broad, shoal continental shelf in a
tropical or near-tropical sea. Lesser mangrove
growths on lagoonal shores seem to be incomplete
approaches to this disposition of the swamp.
Mangrove swamp forests extend along the
coasts of the biogenous sectors (4, fig. 14) with an
extension on the drowned karst (2.1), and on the


southwestern Gulf coast (1.11 and 3). The
swamps occur either in lagoons or on outer coasts
that lack beaches or cliffs. It is along the beach-
less and cliffless coasts, in quiet shallow waters, that
the unique mangrove ridge and lagoon are found.
Davis (1940) reports the growth on Florida as one
of the greatest known. The tropical and near-
tropical mangrove forests of the main biogenous
environment are dominated by the red mangrove
(Rhizophora mangle) and the white buttonwood or
white mangrove (Laguncularia racemosa). Inland
from the widely flooded zone, the black or honey
mangrove (Avicennia nitida) grows. The latter
outruns the other mangroves into the marginal
tropical regions north of the main biogenous
environment. The black mangrove grows as far
northwest as the Chandeleur Islands of Louisiana
off the eastern part of Mississippi delta and in
spots in the Laguna Madre near the mouth of
Rio Grande. In the mangrove forests of southern
Florida numerous other trees and plants grow
with the mangroves (Davis 1940).
The fact that red mangroves build out the shores
on which they grow has long been known to
geologists (Vaughan 1909). The abundant roots
and the manner of seeding on shoals by the floating
of well-sheathed seedlings aids these trees in
occupying marginal marine and lagoonal areas in
protected waters (Davis 1940). The black man-
grove, however, seeds immediately under its
branches, and tends to grow toward land from a
shoreline fringe, rather than outward.
The mangrove barrier ridge and coastal lagoon.-
Chart 1113 shows an extremely irregular outer
shoreline beginning at the north with the Ten
Thousand Islands archipelago. This belt of
islands starts at the northwest in the coastal
lagoon behind the Cape Romano barrier spit. It
then curves to the southeast to end at Lopez
River. From Lopez River southeastward to Cape
Sable the mangrove swamp of the outer coast is
mapped as being much more compact than in the
Ten Thousand Islands, and is smoother, but far
from regular. It is broken by transverse marshy
channels and has, in the northwestern part, an
outer line of islets and small peninsulas. From
3 to 8 miles inland, there is a zone of highly
irregular, more or less intercommunicating swampy
lagoons and channels running roughly parallel
with the outer coast. Between the inner lagoons
and the outer coast, there is a broad belt of man-

grove swamp which is the ridge. Davis shows
that the height of the ridge should be a function
of both tidal range and the slope of the bottom
and adjacent land surface across which the man-
grove belt originally spread.
The entire coast southeast of Cape Romano
(4.1) is composed of mangrove swamps and la-
goons except for the sandy barrier islands, spits
and beaches of the Cape Romano barrier at the
northwest and of Cape Sable at the southeast.
The delineation of shorelines for the mangrove
forest is difficult (McCurdy 1947) because of the
indefiniteness of shoreline position for a marine
swamp, especially where the tidal range, as here,
varies from about 2 to 4 feet. East of Cape
Sable, there is a mangrove belt along the north
side of Florida Bay.
The mangrove peat rests on limestone rock,
marl, or shell beds (Davis 1940). The peat sec-
tion varies from about 5 to 14 feet. Except where
it descends into depressions in the karst, Davis
thinks that the general average thickness is about
7.5 feet below mean low water. This would place
the base of the peat at an average of 8 feet, or
slightly more, below mean sea level. The red
mangrove seats itself in as much as 2 feet of water,
the roots spreading outward somewhat. The
seedlings float and ground in a few inches of water.
There was in many cores taken by Davis through
the peat, an alternation of peat and marl, with an
upper marl bed a foot or two thick present in
most of the area. The roots of the present swamp
trees penetrate this upper marl but without peaty
development in it as yet. Alternations of marl
and peat in a core may or may not indicate a ver-
tical oscillation of sea level, as they, certainly in
some cases, have been due to compaction or minor
horizontal shoreline changes under essential still-
stand of the sea.
The history of the formation of the mangrove
barrier ridge and lagoon may be somewhat as
follows: On a broad, well-protected tropical to
subtropical shoal coast, especially, as in Florida,
where the wind is dominantly offshore but swell
and some on-shore wave movement is present, ad-
vance of the mangrove forest is assured. The
elongated, winged, pod-shaped seedlings ground
and take root at any depth down to 6 to 8 inches
of water. Root growth may extend as far offshore
as a 2-foot depth at low tide (Davis 1940). The
dense growth of roots, trunks, and associated veg-


etation, slowly advances seaward by the consoli-
dation of peaty growth and by trapping fine-
grained inorganic sediment (Vaughan 1909).
Shells are added by the accumulation of small
species of Mollusca on the roots (Davis 1940). It
may be assumed that the maximum of accumula-
tion of marl, clay, and silt takes place always
somewhat forward, that is, gulfward, in the slowly
advancing swamp. Storm waters and tidal os-
cillations combine to permit the up-building of
the accumulating swamp materials by these inor-
ganic sediments which, in turn, may promote, at
and above high tide levels, a denser undergrowth
of the less aquatic plants.
As the zone of maximum arrest and accumula-
tion of inorganic sediment advances Gulfward,
lack of accretion or a decrease in rate of accretion
in the zone nearer the original mainland permits
normal compaction of peat and marl to show in
an invasion of groundwater and brackish marine
waters. The swamp is abundantly penetrated all
along the western peninsula coast by transverse
tidal scour channels, permitting Gulf waters to
enter the rear zone.
If the foregoing processes and results depict the
true history of the formation of the mangrove
barrier ridge and lagoon on the western coast of
peninsular Florida during the stillstand for the
3,000 to 5,000 years of Fisk's (1944) determin-
ations, then the considerable width of 5 to 10
nautical miles of the mangrove belt is a product
of the extended period of time during which ap-
proximate stillstand has persisted. If minor
oscillations have occurred during this period, then
some of the alternations of peat and of peat marl
and in the types of peat reported by Davis may
have been related to changes of sea level. An
end condition of seaward advance may be found
where the bottom slopes too steeply, or the growth
has finally reached a zone where the processes
outlined no longer produce bottom offshore that
is sufficiently shoal to support mangroves. Under
this hypothesis, we may understand why the man-
grove growth on the southern part of the Gulf
shore of Florida is exceptionally wide, as the
combination of conditions required for the full
formation of a mangrove ridge and lagoon are
exceptional. Under this hypothesis the rate of
Gulfward advance is the ratio between the width
of the ridge, 30,000 to 50,000 feet, and the dura-
tion of stillstand, 3,000 to 5,000 years. Using the

figure 5,000 from Fisk's estimate, we find that the
net outward advance of the mangrove forest has
been between 6 and 10 feet per year. This is a
measurable quantity.
It has been said that Davis (1940) finds the
present swamp forest to be resting on and rooted
through a surficial zone of marl a few feet thick
without appreciable peat deposition in it. Hence,
his interpretation that the accumulation of the
average of 7.5 feet of buried peat and marl took
place mainly during a rise of sea level seems not to
conflict with the present writer's hypothesis for
forward growth during stillstand. Accumulating
dating by the deterioration of radiocarbon may
permit a rate of upward growth, less compaction,
to be made, Davis having found no means of
doing so.
The mangrove barrier ridge and coastal lagoon
are similar, in accomplishing appreciable shoreline
prograding, to the other barriers known, the barrier
island of sand, the barrier coraline reef and the
rare barrier oyster reef, noted in the Gulf of
Mexico where a large reef of Crassostrea virginica
forms a bay barrier 25 miles long across the mouth
of Atchafalaya Bay.

Johnson (1919) laid much stress, in his shoreline
studies, on the determination of whether the
features of a shoreline were dominantly those of
the relative submergence of a land surface or the
relative emergence of a sea bottom. His interest
centered in the immediate history of sea level and
its effect on shorelines. Others have found it
impracticable to discriminate entirely on many
coasts between the exact form of the present
shoreline and the topography of the coastal zone
which has determined major features of both
coast and shoreline (Shepard 1937a, Price 1939).
This distinction involves the difficulty in deter-
mining for each sector whether the several sub-
mergences or emergences of the coasts during
the Pleistocene have produced its dominant
A major shortcoming of the Johnson classifica-
tion or the way in which it came to be applied was
its use of the common and widely developed
barrier island as either a major criterion or a


positive indicator (Price 1939, Johnson 1938) of
emergence. Later work, here discussed, seems to
invalidate this criterion entirely as an indicator
of sea-level movement except where it may be
found wholly emerged or submerged.
While not finding the concepts of submergence
and emergence as valuable for shoreline classifica-
tion as some others, we may well inquire what
features plainly indicate such items of shoreline
Pleistocene entrenchment of stream valleys.-It is
well established that the accumulation of large
amounts of ice in the arctic and circumarctic
regions several times during the Pleistocene, or
Great Ice Age, caused strong lowering of sea
level. The latest well-established major lowering
occurred in the late Wisconsin or Wurm glaciation
and amounted to about 450 feet in the Gulf of
Mexico (Fisk 1944, 1952) and the Gulf of Paria,
south of Trinidad, Venezuela.14 In some regions
the figure is set at between 240 and 350 feet
(Flint 1947). Fisk (1944, 1948, 1952) has shown
by borings cited in various reports of the Corps
of Engineers that the northwestern Gulf coast
had a large number of entrenched Pleistocene
stream valleys that have now been filled with
sediments. Configurations of branch estuaries
show that entrenchment was general in the Gulf.
Only on the hard shelf off peninsular Florida are
such valleys found submerged and fairly well
outlined by depressions. These valleys are marked
by depths of as much as 10 to 15 feet on the coast
charts off northern peninsular Florida.
Embayed drowned valleys.-Incompletely filled
drowned valleys in the Gulf take at least two
forms, those in which the branching, dendritic
pattern of drowned tributaries is still prominent
(Baffin Bay in Texas) and those in which waves
and currents have broadened the valley at shallow
depth, producing oval, rounded or other equidi-
mensional shapes. The writer (Price 1947) has
shown that on the northwestern Gulf coast elon-
gated drowned valleys tend to become segmented
by spits and other obstructions, separately em-
bayed by segments and the bay bottoms made
flat under a dynamic equilibrium between erosion
and deposition. This equilibrium of basin shape

1' Personal communication, T. H. Van Andel.

is actually the result of the formation of equilib-
rium bottom-profiles along most bay radii.
Embayment of drowned streams is most
prominent in the Gulf on the compound Pleisto-
cene-to-Recent deltaic coast of Texas and south-
western Louisiana. There, the rivers are large
and the gradient of the Beaumont is not steep
(1 to 3 feet per mile). On the steeper plain of
Sector 1.2 (fig. 14), only one large, transverse
valley bay (Mobile Bay) occurs. Where the
plain is composed dominantly of active deltas or
hard rocks or has only relatively minor streams,
Sectors 1.11, 2.0 and 3.0, long broadly embayed
stream valleys are absent. The writer has further
considered local meteorological influences in the
shaping of the bays of the northwestern coast
(Price 1952).
The harbor of Matanzas, Cuba, is thought to
be a drowned valley cut in a structural depression
or in a structurally weak zone.
Submerged base of mangrove peat.-Davis' (1940)
conclusion that the mangrove swamps and peat
of Florida formed during a gradual, more or less
uninterrupted rise of sea level from about -8 feet
relative to mean sea level has been mentioned.
Drowned lacustrine plain of Florida Bay.-
Anaylsis of this unusual type of marine area needs
somewhat extended exposition. The entire water
area (Trask 1939, pp. 292, 293) is a honeycomb
of shallow, rimmed basins individually upwards
of 10 miles wide and 11 feet deep, the bottoms
bare with a cover of soft marl or shell sand. The
narrow rims are of marl and mangrove peat
(Davis 1940). The writer's interpretation is that
a rising sea moving up and across a very gently
sloping shoal surface carried with it a transgres-
sive shoreline zone of mangrove swamp. This
coastal swamp belt, the mangrove ridge, moved
slowly north and northeastward and is now present
along the north shore. This ridge is of irregular
shape and the marsh and swamp back of it to the
north are now and were probably at all times
honeycombed with lakes. Such lakes tend to
become enlarged by wind scour if the banks are
not encroached on too strongly by marsh and
swamp growth. The result is that some large
lakes occur among the innumerable small ones.
It is further postulated that, as the Gulf waters
invaded the swamp, more and more deeply,
vegetation was slowly killed, and the lakes
gradually widened by drowning and wave erosion.


The outlines of the lakes and rimmed basins of
Florida Bay today show the characteristic coa-
lescing of small basins with each other and with
large ones, the intervening rims being removed.
The lacustrine plain, the so-called bay, with its
network of marl ridges prevents the development
of appreciable tidal flow and scour in and be-
tween basins except along the border of the bay
at the south. Here tidal channels have been
scoured through breaks in the line of the Florida
Keys, locally deepening the rimmed basins.
Statistical study of the relation between width
and depth in the rimmed basins shows a rough
approximation to the progressive deepening with
increasing size characteristic of the bays of the
northwestern Gulf (Price 1947). In the Bay of
Florida this relation is modified on the southeast
by the limiting depth of the hard Miami o6lite
and at the extreme west by an excess of sandy or
marly deposition in the relatively large basins
that there border the Gulf. Some of the western
basins are completely filled with sediment.
Partly submerged eolian sand plain of Rio
Grande delta region.-Stretching inland across the
Pleistocene plains of this delta in Tamaulipas and
Texas to their inner erosional scarp is a plain of
eolian sand, or erg, with scattered dune fields.
All, except small blowout fans of bare sand (about
1 by 3 miles in size) and their fields of bare dunes,
is stabilized by grassy vegetation, thorny brush
and live oaks. The coastal lagoons now form
traps for eolian sand blowing inland from the
beaches of the barrier islands. Only in droughts is
some of this sand able to cross to the mainland
over narrow flats that locally close the coastal
lagoon. This immense sand plain must have come
on shore before the barrier island was formed.
The simplest explanation follows that of Daly
(1934, pp. 197-201) that large amounts of sand
probably blew on some shores when the sea level
was low during one or more of the glacial periods.
Other possible explanations are that the sand
has come from the reworking of successive barrier
island sands and other beach deposits or from
sandy sediments in the walls and on the floors of
entrenched valleys.
Pocket harbors (emergent rimmed basins) of
Northwestern Cuba.-Several writers on Cuba (as
Hayes, Vaughan, and Spencer 1901) have referred

to the purse-shaped or pocket harbors of Cuba.
Those of the sector from Havana to Bahia Honda
(fig. 12) on the northwest coast are of an unusual,
petal-shaped type. They lie in a plain from 3
to 5 feet above sea being upwards of 6 miles
long. A small stream usually enters one or
more of the several marginal indentations of the
small rounded-to-oval basin, not always in the
axial position. Other similar marginal indenta-
tions have either no appreciable inflowing drainage
or receive very slight drainage. Yet well-formed
submerged channels converge from all these in-
dentations toward a central channel of tidal type.
This channel may be as deep as 8 fathoms. Such
harbors do not seem to the writer to be explicable
as normal embayments of drowned stream courses
or of stream confluences, as some have suggested.
If the coast of Cuba west of Bahia Honda (3.1,
fig. 14) is examined on the navigation charts,
basins similar to the pocket harbors and the
rimmed basins of the Bay of Florida, lying in
swampy terrain, will be seen here and there be-
hind the Colorados Barrier Reef, mostly clustering
toward the mainland shore. These basins have
axial or radial tidal channels draining to the Gulf
below sea through passes or breaches in the reef.
These small, rounded and rimmed basins of the
Colorados lagoon seem to be features of a present
mangrove-lined shoreline like those along the
north shore of Florida Bay. The writer inter-
prets the pocket harbors of the Havana type,
surrounded by a slightly elevated plain (Palmer
1945), as similar mangrove lakes scoured out at
sea level in the midst of a saline swamp and then
slightly elevated on the unstable young orogenic
coast (Sector 3) of Cuba.
Barrier Island not an indicator of long-period
sea-level change.-Johnson (1919, 1925) thought
that his offshore bar, called barrier island by the
writer (Price 1951a, Shepard 1952), was a feature
predominantly of an emergent shoreline. He be-
lieved that the structure was formed by a semi-
permanent sea level change, a slight worldwide
lowering of sea level or an upwarping of the crust,
along an offshore bar formed originally as a sub-
marine feature. Fenneman (1938, p. 4), following
some early writers, believed, however, that a
barrier island was formed merely as an equilibrium
structure produced on a shallow shelving coast by
the balance between wave attack and bottom re-
sistance regardless of any history of sea level


change. The writer's study of bottom profiles in
the Gulf (fig. 15) indicates that barrier islands are
(1) associated with well-developed equilibrium
profiles, (2) on a shallow coast where the bottom
is now at least 15 to 45 feet deep within one to
two miles of shore and (3) thereafter slopes out-
ward between about 2.0 and 5.0 feet per mile, (4)
where sand, gravel or cobble are abundant along
shore, and (5) where onshore wave attack is strong.
These observations tend to confirm Fenneman's
interpretation. Other observations, briefly stated,
indicate that the barrier island does not require a
worldwide or other semipermanent fall of sea level
to bring it above sea, but that the only change in
level needed is a local, short-period change be-
tween storm levels and normal sea levels taking
place during periods of a few hours or days.
A series of aerial photographs taken at intervals
of several years over the period 1934 to 1949
(Bates 1953) shows that a bar formed just below
the intertidal zone off a new mouth of Brazos
River remained submerged until a hurricane
had occurred, after which it became a typical
emergent barrier island of cuspate outline. A
second bar then formed off a breach in this bar-
rier, after which other hurricanes occurred before
the second bar was, in turn, raised above sea to
form a second line of emergent barriers. The
inference is strong that, in each case, a pre-existing
submarine bar was built higher during a hurricane,
so that during the storm it bore the same height
relation to the elevated storm sea level as it had
formerly borne to the normal level of the Gulf.
The bars emerged as barrier islands after the
subsidence of the temporarily high sea levels.
On October 3, 1948, a hurricane passed about
100 miles off the coast of southwestern Texas,
causing a high sea level or storm tide of some 3 or
4 feet for two days or more along the barrier
islands. A week later, the writer found that the
summit of the beach, the beach ridge, in front of
the shore dunes had been built up and remade by
the storm and was slightly farther inland than its
former alignment. The shift in position was evi-
denced by erosion of dune faces. The convexly
rounded beach ridge then rested where the front
part of the dunes had been.
The raising of the beach ridge, previously
described, to an elevation above its position
during normal times was shown by the rapid
mass-wasting that had affected it in a single

week. The beach ridge on this island formerly
had, in places, a fairly well developed pavement
of shell, but now the pavement had just begun
to be formed on the newly made ridge. The
pavement was formed from disseminated shell by
the washing and blowing away of sand, according
to a well-established process. It was evident that
this ridge had lost some 6 inches of its height and
would lose another foot or a foot-and-a-half before
a pavement would be formed to protect it. The
former paved beach ridges had evidently lost
similar heights.
Reports and illustrations of hurricane damage
to New England beaches (Brown 1939, Howard
1939) show that the beach ridges were remade at
higher levels, moved inland from their for.cier
positions and their axes rotated slightly by the
hurricane waters.
These observations indicate clearly that the
summit ridge of a barrier island functions briefly
during storm tides as an underwater offshore bar
and thereafter emerges as a barrier island.
Evans (1942) found that waves operating at a
steady sea level tend to modify the slopes and
positions of underwater bars, but not to build
them up above water.
The great development of active barrier islands
on the Gulf coast, dominating the shorelines of
the alluvial sectors (1, fig. 14), does not then, in
the writer's opinion, tell a story of permanent or
semipermanent sea level change, or mark either a
submergent or an emergent shoreline condition.
The question of the source of the supply of
material for the barrier, long thought to be a
critical factor, is found to be secondary. Thus,
barriers occur in the Gulf where longshore sedi-
ment drift is prominent (Sectors 1.12, 1.2, fig. 14)
the sand derived largely from rivers (Bullard 1942),
also where a longshore drift from a land connec-
tion (Chandeleur Islands, La.) is absent and
where no land-derived sediment is present but
onshore waves are strong and the barrier is built
of broken shells from the adjacent bottoms, as on
the north shore of Yucatan (2.2, fig. 14).
Emergent shoreline terraces and notches.-The
lowest well-established elevated shoreline is that
of the Pamlico of the Atlantic coast and Florida,
standing at about 25 feet above mean sea level.
This shoreline is marked in many regions by a
well-cut and well-preserved terrace or by a broad
elevated lagoon flat with a barrier island. Less


well-developed and somewhat controversial shore-
lines are reported from many places in the interval
from about +3 to +10 feet. However, carefully
selected, stable, protected, inner shoreline sectors
on North Pacific Islands (Stearns 1941, 1945) and
in Australia (Fairbridge 1948) exhibit shoreline
cliffs in even-grained limestones with solution
notches at about +3, +5 and +8 feet. These
seem to represent worldwide stillstands of the
sea (eustatic shorelines). Shorelines reported at
+16 and +20 feet (Daly 1934 and others), are
not as yet substantiated by data of unquestioned
In places around the shores of the Gulf, there
are definite indications of shoreline terraces that
seem to indicate stillstands at about +5 and +8
feet. An elevated barrier island and coastal
lagoon caught by the 10-foot contour has been
mapped in Florida by MacNeil (1950) as the
"Silver Bluff shoreline" (Parker and Cooke, 1944,
pl. 4, fig. B). He did not follow it across southern
Florida or on the west side of the peninsula.
Low shoreline flats appear in many places around
the Gulf, but have not been critically studied in
the field. Such a low bench shows in air photo-
graphs along the base of the high bluffs of the
Champoton-Campeche limestone fault-block sali-
ent (fig. 12; Sector 2.2, fig. 14). It seems to have
a gray, sandy soil. A flat along the front of the
elevated Ingleside shoreline between the Rio
Grande and Brazos-Colorado deltas (fig. 12) lying
at from about 1 to about 5 feet above mean sea
level has low, subdued spits and bars on its sur-
face and seems to be an emergent marine plain.
It is about 0.3 mile wide. This flat may be a
nondeltaic part of the original Pleistocene surface
in front of this barrier. Deltaic deposits appear
along the Gulf side of this barrier east of Galveston
Marsh borders the Pleistocene delta of Brazos
River in Texas to an elevation of 2 to 3 feet above
mean sea level. Just behind the marsh is a bench
1.0 to 1.5 mile wide at 3.0 to 4.5 feet with a low
nip or wall between 4.0 and 6.5 feet above sea.
This bench may be a low Silver Bluff representa-
At Buhler, a few miles northwest of Lake
Charles, Louisiana, the Ingleside barrier and
lagoon clays are well preserved. The top-of-clays,
is Obscured by mima (pimple) mounds higher and wider than the spits
(Prioe 1949).

representing the approximate shoreline position,
lies between 22 and 25 feet above sea. This shore-
line and the associated features are well defined
running at the same elevation from near Lake
Charles west to Beaumont and thence southwest
through Fannette, Jefferson County, Texas.
Where the shoreline comes within about 10 miles
of Anahauc, Chambers County, it is sloping down
to the southwest at about 1.5 feet per mile and
reaches sea level at Smith Point on the shore of
Galveston Bay. Before the formation of the bay,
it was formerly tied there to the Brazos delta.
The Ingleside shoreline seems to correlate with
the Pamlico through the emergent barrier of
Gulfport and Biloxi, Mississippi.
The deltaic plain lying south of the Ingleside in
southwestern Louisiana and in Jefferson and
Chambers counties, Texas, is of the same age as
that immediately -to the north of it, Prairie or
Beaumont (Hayes and Kennedy 1903, pp. 27-38;
Deussen 1924, p. 110). Along the shore of Jeffer-
son and Chambers counties, it is a partly sub-
merged deltaic plain.
The Ingleside appears again south of the
Brazos-Colorado delta along the coastal lagoon
that opens from Matagorda Bay at its southeast
extremity and runs from there to the north flank
of Rio Grande delta, the shoreline (top of clay)
being at approximately 5 to 10 feet above sea.
The disagreements in the shoreline data for the
northern Gulf coast would be removed if the coast
from Florida to the Mississippi delta had been
stable since Pamlico time, but a slight amount of
gulfward downwarping had occurred between the
vicinity of Galveston Bay and the coast of Mexico
at some point north of Tampico.
The post-Pleistocene gulfward downwarp of the
Beaumont Pleistocene plain (Doering 1935) in-
creases in amount from about 1 foot per mile in
southeastern Texas to 2 feet per mile southwest of
Matagorda Bay. This downwarp seems to mark
the influence of the young orogenic coast of
Mexico, which it is approaching." This interpre-
tation suggests that the emergent shoreline flat on
the Gulfward flank of the Ingleside barrier may be
either of Ingleside age, downwarped some 15 feet,
or a younger post-warping shoreline, possibly of
Silver Bluff age. Against a Recent age for the
low bench is the seeming absence of marine fossils
16 Corpus Christi lies 175 miles east of folded Cretaceous rocks at the surface
in Mexico and 125 miles northwest of submerged mountains in the Gulf.


above present sea level in the much cored and
studied post-Pleistocene alluvial fill of Mississippi
River in the Atchafalaya river basin, Louisiana
(Fisk 1952).
No unquestionable evidence seems yet to have
been offered that elevated, unwarped (eustatic)
shorelines below +25 feet are of Recent or post-
Glacial age, despite continued statements by
many geologists that they "seem to be Recent."
R. W. Fairbridge and E. D. Gill of Australia 17
think that the materials of the shorelines of Australia
below +10 feet are not sufficiently weathered and
leached to have been formed before the last major
sea level lowering. On Chesapeake Bay, G. F.
Carter is finds no post-Pleistocene deposits above
a maturely developed soil, supposedly of post-
Pleistocene age, which dips beneath bay sediments
and has been cored into off-shore. We do not
know that the shores of the Chesapeake have been
downwarped. The Pamlico terrace is reported as
running level along this coast from Maryland to
The only dated shoreline deposits above sea
level that are thought to be of historical or earlier
Recent Age of which the writer has been able to
learn, come from young orogenic coasts, as that of
Tripoli in Lebanon (Wetzel and Haller 1945)
and on the Pacific coast of South America. These
coasts must be suspected of having had crustal
movements going on at any time, even in recent
millenia. Thus, Jerico, 175 miles southwest of
Tripoli, was once destroyed by an earthquake and
200 historical shocks are reported for the area of
Israel (Ball and Ball, 1953).

Terminology.-Shepard (1937a; 1948, pp. 70-73)
says that "as numerous coasts and shorelines have
undergone little modification since the sea level
and the land came to rest, it seemed logical to re-
fer to these as Primary . and to . those
which have been considerably modified by the
waves and currents as Secondary . ." In his
tables he calls "primary" shorelines youthful and
"secondary" coasts mature. Following this con-
cept, we find that mature marine coasts have in
17 Letters of 1952.
I8 Letters of 1952.
19 At 2 to 3 meters above sea 600 m. inland and possibly 3,000 to 4,000 years

general become simplified in contour, with their
irregularities reduced by erosion, solution or sedi-
mentation, or a combination of processes. Hence,
the end result of marine action on most types of
coasts is smoothing, though not always straighten-
ing, as smooth coasts may be curved.
Processes.-Simplification of a coast may con-
sist of the reduction of projections by erosion, and
the deposition of beach and other deposits in re-
entrants. It may also be brought about by the
formation offshore in shallow water of a barrier
island or barrier spits (Price 1951a, Shepard 1952).
Such inorganic barriers tend to follow along a bot-
tom contour, crossing the sites of entrenched
valleys on postentrenchment fill, while the main-
land shoreline is deeply indented by the shallow
embayments of the former valleys. Thus, the
new marine shoreline is smooth and shorter than
the mainland shoreline off which it is built.
Examples.-Simplification of Gulf shorelines is
shown by (1) extensive development of sandy bar-
riers where there are or were irregularities of the
mainland shoreline, chiefly between the convexities
of deltas (Sector 1), (2) the gradual filling of coastal
lagoons (as east of Galveston Bay, sector 1.2), (3)
the incipient smoothing of projections along some
sectors of the drowned karst coast (2.1), (4) seem-
ingly some smoothing of the front of parts of the
mangrove ridge (Sector 4.1) facing the Gulf, in
contrast with a possibly irregular original con-
figuration such as that of the Ten Thousand Is-
lands or the north shore of the Bay of Florida,
(5) smoothing of the karst irregularities of the
elevated Champoton-Campeche fault-block (Sector
2.2, YucatAn peninsula) so that only small cuspate
points remain, (6) reduction by erosion of project-
ing folded limestone rock (northern Sector 3.1)
and of the ends of narrow tongues of lava solidified
to rock extending into the Gulf from the active
volcanic salients of the young orogenic coast of
Mexico (southern Sector 3.1).
Significance.-The several degrees of shoreline
simplification evident in the preceding list, sug-
gest a considerable quantitative range in the
effective application of marine energy to shoreline
modification during the 3,000 to 5,000 years of
essential stillstand of the Gulf. Just as we find
variation in simplification related to the hardness
and resistance of the shoreline materials, rocks or
soft sediments, so we may suspect that there have
been differences in the amounts of energy available


for shoreline work. This supposition is justified
by (1) the consideration that erosion at the shore-
line has a vertical as well as a horizontal com-
ponent, (2) comparison of variations in the form
and offshore gradients of the bottom of the
continental shelf on various sectors of the Gulf,
and (3) inspection of the charts of resultant winds
along the shorelines of the Gulf (U. S. Weather
Bureau, 1938). These factors indicate that it
may be feasible, from the partly quantitative,
partly qualitative data presented or referred to
here, to set up a preliminary energy classification
of the coasts and shorelines of the Gulf of Mexico.
This is attempted in the tabulation.
Extensive Marine Modification of Coasts of
Gulf.-A summary of prominent shoreline condi-
tions that indicate the degree of coastal modifica-
tion is shown in tabular form below. The simpli-
fied coasts (the secondary or mature coasts of
Shepard) greatly dominate in linear distribution,
indicating that the sea has been at about the same
level for a substantial period of time in relation to
the resistance of most of the coastal materials to
shoreline modification.

Gulf and major parts:
Marine shoreline-----
Coastal plains --------------
Volcanic and other sectors -----
Secondary shorelines:
Simplified (smooth) ------
Moderately smooth --------
Little modified -------------
Sandy beach----------. .....
Barrier islands and bay bar-
riers ---_--------_- -
Inactive and elevated beach
plains ..---------
Beach ridges, average of 10 (?)
ridges per beach ........-..

Approximate of marine
length in shoreline
statute miles length
3,000 100
2,500 83 100
500 17J100

2, 250 75]
250 8 100
500 17J
1, 553 52

1,370 46

810+ 27+

20,000+ 667+

Definitions.-Figure 15 shows bottom profiles for
sectors of the continental shelf having different
steepness of curvature. Only for the broad shelves
off the alluvial and limestone plateau coasts (fig.
14, Sectors 1 and 2) of the Gulf of Mexico are there
enough data for analysis. On the shelf sectors
studied, the profile of the bottom is concave in the
first mile or two, this section being the shoreface,
an extension of the beach or other shore. The

shoreface grades into a nearly smooth plain, here
called the ramp, the gradient of which flattens
slowly in an offshore direction for varying dis-
tances, commonly to 30 fathoms or more. The
profiles drawn on this section of the shelf are math-
ematically of the hyperbolic or asymptotic type,
the so-called logarithmic or exponential curves.
The ramp grades, usually far offshore, into a
usually smooth convex section, here called the
"camber," the gradient of which usually increases
rapidly to the top of the irregular, steep, conti-
nental shelf slope. The sparse soundings available
for the shelf of the young orogenic coast of Mexico
(3, fig. 14), suggest that, except where a beach or
barrier is present, this coast may lack a ramp, the
camber beginning at or near the base of whatever
shore cliff or shoreface is present. The so-called
shelf break (Dietz and Menard, 1951) should be
the junction between ramp and camber.
Data showing the locations and ramp slopes of
the profiles (curves) of figure 15 and the sectors
on which the curves are located are given in a
tabulation following the illustration.
Location of profiles in figure 15.-All profiles
measured perpendicular to shoreline from naviga-
tion charts U. S. Coast and Geodetic Survey.
(1) Off old Corpus Christi Pass and Padre
Island barrier island 27035' N. Lat., 97'13' W.
Long. Chart 1286, 1922 edition. A profile at
same place from original survey sheet (1880)
shows only minor irregularities and smoothly
asymptotic curvature to 90-foot depth. Beach.
Sand and clay bottom.
(2) Off Padre Island at Baffin Bay mouth,
27018' and 97020'. Chart 1286, beach sector:
"Little Shell." Beach. Sand and clay bottom.
(3) Off Matagorda Peninsula barrier island, off
mouth Trespalacious Bay, 2800', 96010'. Chart
1284,1945 edition. Beach. Sand and claybottom.
Fathogram off Galveston shows ramp as smooth
as curves 1-3.
(4) Off barrier island on Florida peninsula 10
miles north of Cape Romano, 26003' and 81048/.
Chart 1254, 1931 edition. Beach. Sand inshore.
Rock bottom (limestone) with some sand and
(5) Off Pine Islands-Key West shoals (Miami
o6lite with mangrove swamp deposits above),
Florida, at Johnson Keys, 24042', 81036'. Chart
1251, 1940 edition. Profile begins at -8 feet.
Add 8 to all depths for this curve in figure 15.





FIGURE 15.-Characteristic bottom profiles of inshore zone, continental shelf, north half, Gulf of Mexico. Steepening
and progressive smoothing of bottom from profile to profile correlates with increasing energy of water, decreasing
resistance of bottom, and increasing steepness of initial drowned surfaces. The theoretical low-energy, breakerless
profile of Keulegan and Krumbein (curve 7) is compared with a beachless sector of drowned karst coast off Florida
(curve 6). Profiles are listed on pages 59 and 60. Sectors are described in tabulation, pages 61 and 62. The shore-
face extends 1 to 4 miles offshore. The ramp extends out from the shoreface as far as the profile continues to flatten.
The outer parts of profiles 1 and 2 are averaged between the points shown.

Bottom "hard," mostly o6lite limestone. Little
sand reported in region. Beachless.
(6) Off rocky coast of Florida at Net Spread
Key between Chassahowitzka and Weekiwachee
Rivers, 2838', 8240'. Chart 1258, 1944 edition.
Beachless. Hard bottom (limestone). Very few
notes of sand in region.

(7) Theoretical mathematical curve of Keulegan
and Krumbein (1949) for the steepest bottom
across which waves will move with the maximum
height without breaking. A wave 3 m. high
enters the shelf-sea on a bottom 4 m. deep 40
km. from shore. Depth equals the 4/7 power of
the distance from shore. A hyperbolic curve.


TABLE 1.-Gradients of ramp shown in figure 15



6..... .. ------

5.--- -.. -.. ----
4 ,- - - - -
3 - -- - -



miles from

0.1- 0.6
.6- 2.2
2.2- 7.4
7.4-15. 0
15. 0-25. 0
0 -4.0
0 -13.0
13.0-27. 0
0. 9-11.0
1.0- 4.0
4.0- 8. 5
1.8-12. 2

Depth in

0.5- 1.6
1.6- 3.3
3.3- 6.6
6.6- 9.8
1.0- 7.0
10.0-40. 0
25. 0-44. 0
44. 0-57.0
44. 0-67. 0
54.0-87. 0

Sector of Gulf

Theoretical "breakerless"
bottom profile, Keu-
legan and Krumbein.



Sedimentation and the profiles.-The shoreface,
ramp and camber of the normal coastal plain shelf,
as exhibited on the Gulf of Mexico, seem to have
specific characteristics as to sedimentation (map,
fig. 16, p. 79) and erosion. From meager data, it
seems that sand and shifting bars characterize the
shoreface. Contemporary sands, relict deltas and
barriers of former sea levels, with some contemp-
orary clay deposition, characterize the ramp. Ex-
cept when the entire profile is migrating landward,
transportation probably dominates the ramp after
any relict elevations have been removed from the
part under consideration. Fine-grained sedi-
ments, mostly land-derived clays, and presumably
the process of deposition, characterize the camber.
Off the mouths of large deltas, little or no coarse
sand reaches the Gulf and the charts show "mud"
beginning near shore. Where sand is present it
usually extends to 5 to 10 fathoms (Bates 1953;
Lohse 1952).
Dietz and Menard (1951) have lately advanced
evidence and argument for the belief that, at the
level of the passage of the shelf from the steep
concavity into the gentler slope, in present ter-
minology, where the shoreface joins the ramp, is
found the depth of maximum wave action on the
bottom. They term it the depth of maximum
abrasion, replacing the older concept of "wave
If the Gulf has remained essentially at the same
level for the past 3,000 to 5,000 years, as pre-
viously suggested, it is evident that, on bottoms
closely approximating the hyperbolic curve the
shelf bottom must be in equilibrium. This should
be true especially in coastal materials of slight
resistance and where large amounts of marine

energy have been effectively applied. That the
topography of the bottom is a simple mathematical
surface with a hyperbolic bottom profile, is be-
lieved to indicate that the forces are in equilibrium.
Where the bottoms are of hard rock and largely
retain a subaerial topography, it may be concluded
that the marine forces have inherited a surface
produced under different conditions which they
have been unable to destroy or to which they
happen to be more or less adjusted.
The equilibrium profile of the coastal plain shelf
is in a state of dynamic, not static, equilibrium.
In dynamic equilibrium, variations of temporary,
short-term value are to be expected. Thus,
heavy storm waves are known to shift offshore
bars 2o temporarily as much as a half-mile from
their previous positions on the shoreface. Varia-
tion of the equilibrium will be about the mean.
Marked departures from the mean are caused
only by forces external to those in equilibrium.
The shift of a river mouth, the coming of a lava
flow, or the warping of the earth's crust, would be
external forces or conditions which might upset a
previously existing equilibrium on the shelf.
Usefulness of equilibrium profile.-Despite some
pessimism (Kuenen 1950, p. 302) as to the value
of the profile in geologic studies and much mis-
conception on the part of writers as to the differ-
ence between static and dynamic equilibria in
nature, the present writer finds that the profile of
equilibrium is a suitable index of the response of
a continental shelf bottom to the application of
marine energy for a significant period of time.
If, as some think, there have been several oscilla-
tions of sea level of as much as 10 to 20 feet during
the past 4,000 years or so, a proposition that re-
mains unproved, then the interpretation of the
modification of the shorelines and shelf by marine
energy is less clear than as here tentatively
Theoretical breakerless curve fits Florida.-Keu-
legan and Krumbein (1949) made a theoretical
study of the critical steepest bottom slope in
shallow water on a shelf across which waves from
deep oceanic waters may move but be constantly
deformed and constantly lose energy so that they
arrive at and near shore without enough height or
energy to break or to develop shore structures,
such as beaches or cliffs. The absence of such

20 The true underwater feature, not the barrier island. This occurred at
Galveston, Texas.


shore structure along much of the western shores
of the limestone peninsulas of Florida and Yuca-
tan, and the low gradients prevailing there off-
shore, led the writer to investigate these regions
for examples of the beachless and breakerless
coasts. More information is available for Florida
than for YucatAn.
It was found that the requisite combination of
(1) unmodified or little-modified shorelines, (2)
gentle offshore slope and (3) essential absence of
breakers (Corps of Engineers, U. S. Army 1940)
exists on long stretches (Sectors 2.1 and 4.1, fig. 14)
of the Gulf shoreline of peninsular Florida.21 By
analogy, similar conditions are believed to exist
on more than half the lengths of the western
peninsular coasts of Florida and YucatAn, where
the bottom gradient is low and the shoreline and
bottom essentially unmodified by marine forces.
Comparison of the theoretical "breakerless bot-
tom" curve of Keulegan and Krumbein (1949),
described as profile 7 (p. 60 and fig. 15) with the
actual rolling bottom profile of the drowned karst
shelf of peninsular Florida (profile 6, fig. 15), shows
that the two curves closely superimpose and are
identical in over-all gradient. But the drowned
karst profile has not been fully smoothed by ero-
sion and deposition and is not yet a marine profile
or equilibrium, although slight modifications of it
indicate that such a development is going on.

In the northwestern Gulf of Mexico, where a
strong longshore sediment drift occurs, and
wherever a barrier spit terminates, the dominant
drift of the year is in the direction of the elongated,
pointed barrier ends.22 These criteria agree
there with the known' histories of inlet migration,
although there is a weaker summer drift to the
northeast. Using spit criteria, the dominant
longshore drift is seen to be westward and south-
westward, that is, counterclockwise,23 from Apa-
lachicola delta, Florida, to the poorly mapped
volcanic sectors (Sector 3, fig. 14). Where sandy
beaches and barriers occur on peninsular Florida,
31 The data on waves and swell are being studied at the Agricultural and
Mechanical College of Texas by Charles Bretschneider (Bretschneider
and Reid 1953).
22 The so-called Gulliver's rule (Johnson 1919, p. 376) cannot be applied
here successfully in all cases from chart data and is of doubtful validity
in any case. See Bullard (1942) and Price (1952).
2 With reference to the center of the Gulf.

longshore drift occurs. A northward drift exists
for 20 nautical miles from the headland at Indian
Rocks (270o52' N. Lat.) to Anclote Keys. A
much stronger south-southeastward drift exists
from Indian Rocks to Cape Romano and its large
underwater bars, a distance of 75 nautical miles.
Southeastward drift again appears south of Cape
Sable, where fine-grained sediments have been
carried into the northwestern part of Florida Bay.
Colorados barrier reef at the western end of Cuba
diverges from the shoreline to the west, suggesting
a clockwise drift.24 Split ends indicate a clockwise
drift (to the west) on the north and northwest
coasts of YucatAn to the Laguna de Terminos
(Sector 1.11, fig. 14).
The unmodified and slightly modified drowned
karst and mangrove ridge shorelines do not show
appreciable longshore drift, judging by their
irregular shorelines and dominantly transverse
tidal channels. Convergence areas exist at the
cuspate delta of the Apalachicola and the cuspate
foreland of Cape Sable, Florida. The cuspate
foreland of Cabo Rojo (fig. 12; Sector 3, fig. 14), is
asymmetrical, showing that the counterclockwise
drift persists across it despite convergence.
Bates (1953) shows from photographs and ocean-
ographic data that there is a Coriolis effect 25
turning Mississippi River water westward along
shore. This coincides in direction with a weak,
westward-moving wind-powered drift. Together
there is formed a dominant counterclockwise
drift (to the right). Distribution of sediments
along the delta front agrees well with this drift.
Air photographs show that the Coriolis drift oc-
curs also at the mouths of the other rivers of
the northwestern Gulf coast. It is not operative,
however, in equatorial and near-equatorial waters
such as the southern Gulf of Mexico.

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p. 121, fig. 34).
28 Relative right hand turning of flows because of the rotating coordinates
of the revolving earth. The turn is to the left in the southern hemisphere.


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By S. A. LYNCH,2 Agricultural and Mechanical College of Texas

The lower Gulf coast and the inner continental
shelf of the Gulf of Mexico are the sites of oil
fields in Veracruz, Tamaulipas, Texas, Louisiana,
and Florida. Therefore, hundreds of geologists,
geophysicists, and engineers are engaged in inves-
tigations of the structure, geologic history, and
sedimentology of the fringe of the Gulf of Mexico.
Due to the economic necessity for research to
discover new trends and new provinces of petro-
leum accumulation and to the many data contin-
uously being furnished by the drill and geophysics,
great strides have been made in the knowledge of
the continental shelf and the adjacent Coastal
Plain of the United States. Even though these
economic studies were of the coastal area and con-
tinental shelf, they have encouraged thought con-
cerning the origin and geologic history of the Gulf
of Mexico.
A modern study of the Gulf Stream was initi-
ated by the United States Coast Survey in 1846,
and some work in the Gulf of Mexico was started
soon thereafter. During the last century, many
capable students of geology have studied the geo-
logical history of the Gulf of Mexico, but there is
still much diversity of opinion concerning its
origin and manner of development.


Early European writers initiated the idea of
North and South America being tied together by
a continuous mountain system, and this century-
old concept is still popular in Europe. Suess
(1885, pp. 283-285) described the Gulf of Mexico
bottom as an elevated "plate" and considered
this plate the foreland of the Antillean chain.
He believed the present deep Gulf did not exist
in Paleozoic time, but an old metamorphosed
and deformed basement formed a somewhat flat
platform that continued southward the low-lying
I Contribution from the Department of Geology of the Agricultural and
Mechanical College of Texas, Oceanographic Series No. 18.
2 Head, Department of Geology, Agricultural and Mechanical College of
Texas, College Station, Texas.
259534 0-54-6

central area of the United States. The present
Gulf of Mexico was formed by the collapse of the
plate during Cretaceous and later time, and the
general outline of the Gulf was "not influenced by
the course of the mountainfolds unless perhaps in
the west by the approach of the Mexican ranges
to the coast of Vera Cruz" (1885, p. 551). The
plate of Suess has influenced geologic thought con-
cerning the origin of the Gulf for the past three-
score years.
Spencer (1895, pp. 103-140) not only believed
that the whole tract of the Caribbean Sea, the
Antilles, and the Gulf of Mexico constituted an
ancient continental region, but he attempted to
restore the topography of the submerged conti-
nent. Using available soundings, Spencer found
drowned valleys which he considered of prime
importance in establishing the existence of a
continental region which ever since the Miocene
had executed vertical fluctuations of an amplitude
of many thousands of meters. In discussing the
area, he stated, "the Gulf of Mexico appears to
have been a plain, with the fjords and embayments
reaching nearly to its greatest depths" (1895, p.
119). Thus, Spencer agreed with Suess, at least
in part, and postulated a Gulf floor more than
12,000 feet above its present deepest position.
Hill (1898, pp. 3-5) believed the Gulf of Mexico
is more closely related to North America than to
Central or South America. He declined to con-
sider most of the Antilles as other than true
oceanic formations and refused to believe that
there is any connection between the northern
Antilles and Barbados-Trinidad, the latter being
by him assigned to the South American mainland.
He saw that the Gulf is nearly surrounded by low
plains composed of nearly horizontal, uncon-
solidated sediments deposited in an enlarged
Gulf of Mexico. This border of plains is in direct
contrast to the Caribbean and its mountainous
Willis (1929, p. 328) held that basins are per-
manent, and he did not believe the Gulf of Mexico


was ever an area of shallow seas over a flat "plate."
This is shown by his statement that
The isostatic equilibrium of the Gulf is inconsistent
with the conditions that should result if a continental mass
had sunk . I, myself, regard the Gulf as representing
a mass of basalt which was erupted in Pre-Cambrian
time, either before or soon after the eruptions of the
granitic nuclei of North America. If so, it has been a
basin ever since . The Caribbean, Yucatan Deep,
and the Gulf of Mexico are, from the point of view of
actual isostatic equilibrium, all of the same nature. They
are, I think, all of them basins of great antiquity.
Van der Gracht (1931, p. 121) discussed the
origin of the Gulf of Mexico and the downbreaking
of Llanoria. He believed the coastal plain
"represents a sunken basin over old central chains"
and that both the Caribbean Sea and the Gulf of
Mexico were part of a great geosyncline and a
"very complicated system of anticlinoria, ridges
and chains . must now fill the original geosyn-
cline, generated by its late-Paleozoic compression
stage. Since then, complete abrasion and renewed
sedimentation . have obscured the original
Fifty years after Suess, Schuchert (1935, p. 340)
confirmed the conclusion of Suess as to the Gulf
of Mexico "plate" and described it as extending
from Tabasco northward so as to include part of
Texas, Arkansas, the southern tip of Illinois,
Alabama, the peninsula of Florida, and the
northern Bahama Banks, as well as other Mis-
sissippi embayment States.
The Gulf of Mexico and the Caribbean were
separated, according to Schuchert, by a Central
American-Antillean anticlinorium until Jurassic
time. By mid-Cretaceous, the Gulf of Mexico
area responded to crustal movements in Mexico
and the Antillean geanticline and began to sub-
side; this downward movement continued until
great depths were reached. Thus, the Gulf of
Mexico was a shallow sea probably from Pro-
terozoic to mid-Mesozoic time, and by late
Cenozoic time the depth had changed from
possibly less than 1,000 to over 12,000 feet.
Schuchert believed the cause of the inbreaking of
the "plate" and the subsequent subsidence was
related to "the geologic structures of the Central
American-Antillean region, those of northern
South America, and those of the present Caribbean
sea bottom" and that all were "due to subcrustal
flowage, to the rising of plutonic masses into the

various arches, and to the subsequent cooling of
these masses." He also believed that-
The present depth of 12,000 feet was surely exceeded
during Cenozoic time, since in the course of this era sedi-
ments thought to be many thousands of feet thick ac-
cumulated upon it . In the latitude of South Lou-
isiana, the ancient Gulf bottom has subsided over 25,000
feet, about twice the depth of the present Mexican Basin
(Sigsbee Deep). Therefore we may say that the greater
part of the Gulf of Mexico has sunk since Middle Cretaceous
time at least 20,000 feet. These are striking facts, in-
dicating slow, but in the end enormous, loading and
isostatic adjustment, accompanied by subcrustal move-
ments and rock flowage toward the rising geanticlines of
Mexico and the Central American-Antillean arch, a move-
ment that is not yet completed.
Barton, Ritz, and Hickey (1933, pp. 1446-
1458) were among the first to publish concerning
the Gulf coast geosyncline, and they presented
both stratigraphic and geophysical evidence for
the existence of a geosyncline in the Gulf coast of
Texas and Louisiana. They showed geophysical
calculations to indicate a horizontal increase in
density of the basement rocks from the Sabine
uplift to near the middle of the Gulf of Mexico,
and they concluded that a geosyncline must occur
in the basement surface with its trough axes
slightly landward from the present coast line
(op. cit., p. 1456). They also showed the great
thickening of the Upper Cretaceous and Tertiary
beds as they dip Gulfward, with the Tertiary
beds reaching a stratigraphic thickness of more
than 25,000 feet near the coast. Knowing that
the deepest part of the Gulf of Mexico is 12,500
feet and assuming that the thickness of the Upper
Cretaceous-Tertiary sedimentary deposits in the
great depths of the Gulf are 10 percent or less of
their thickness in the Gulf coast, it was concluded
that "the basement of the Upper Cretaceous-
Tertiary beds must be down-warped 6,000 to
16,000 feet in reference to the depth of that
basement under the Sigsbee Deep."
The geosynclinal trough is a well-marked feature
indicating considerable subsidence. Its westward
limit is not definitely known, but some thinning
of formations is noted in the longitude of Mata-
gorda County, Texas. It is further complicated
by transverse structures such as the Rio Grande
syncline, the San Marcos arch, the Houston
syncline, the Sabine uplift, and the Mississippi
River syncline.


Howe (1936, p. 82) called attention to the great
sinking in the region of the Mississippi Delta
which he believed amounted to about 30,000 feet
since the beginning of the Tertiary. He believed
the Gulf coast is an active geosyncline resulting
from the weight of the sediments brought down by
the Mississippi River. Evidence of the sinking
of the Mississippi Delta was also presented by
Russell (1936, pp. 167-169) in his study of the
physiography of the region. Russell and Fisk
(1942, pp. 56-59) questioned the "strength"
of the earth's crust and concluded that the crust
appeared "weak" as it yielded and subsided "at
essentially the same rate that the deposits
Meyer (1939, p. 206) did not subscribe to the
sedimentary-load theory and among various ob-
jections stated that the "epochs of reversal of
movement in the geosyncline, indicated by un-
conformities, shoreline migrations, entrenched
streams, submarine canyons, and the elevated
beach at Corpus Christi, are opposed to the basic
tenets of the sedimentary-load theory."
Meyer also used the argument that the ocean
deeps, which are structural troughs, could not have
been caused by the weight of accumulating sedi-
ments. He suggested that the Mexican Basin
and the Gulf coast geosyncline may be related
structures and that the Gulf coast geosyncline
was a "similar structural and topographic basin in
early Tertiary time when the strand-line was far
inland. After this basin had come into existence,
it offered an opportunity for the accumulation of
thousands of feet of sediments. The weight of
the first several thousand feet of Tertiary deposits
may have been sufficient to overcome the in-
herent strength of the crust and to cause further
sinking" (op. cit., p. 206).
Storm (1945, p. 1330) considered the Gulf coast
geosynclinal trough as a well-marked feature
indicating considerable subsidence. He believed
that, if subsidence continued at a fixed position
and if sediment filled this trough and passed over
it, there should be some sign of sinking inland and
drainage should have caused deposition over the
axis of the syncline. Such indications were lack-
ing, and he therefore believed that the shape of
the trough was a composite of past and present.
He showed that sediments are accumulating prin-
cipally on the seaward flank of the trough which
pushes the bottom of the flank downward while

the landward flank rises slightly. Thus, the
trough tends to move seaward with continued
Glaessner and Teichert (1947, p. 586) thoroughly
reviewed the subject of geosynclines and con-
cluded that the origin of geosynclines is still
unknown. Observed facts are too often over-
shadowed by an author's "attitude to one or the
other of the current and mutually exclusive
hypotheses of mountain building and of the
origin of continents on which no finality has yet
been reached. Concerning the actual mechanism
of the formation of geosynclines it would seem that
the school of Gulf coast geologists has produced
such weighty arguments in favor of subsidence
under load that the operation of the factor can no
longer be doubted. On the other hand, there is
evidence for 'autonomous' uplift and subsidence
of parts of the crust which would make it possible
for sedimentary accumulations to be formed as a
result of active subsidence and uplift rather than
of passive depression under the load of shifting
products of erosion."
Bornhauser (1947, pp. 706-711) observed that,
since the Tertiary transgressions affected the
whole northern border of the Gulf of Mexico,
diastrophic movements must have been the
primary cause of the transgressions. He agreed
that the subsidence of the Mississippi embayment
and. the Gulf coast geosyncline caused the Ter-
tiary transgressions of those areas, and the sub-
sidence was due to diastrophic movements.
Bornhauser "has not found clear evidence to
support the idea that the weight of the sedi-
mentary column is the deciding factor for subsi-
dence. On the contrary, all facts and evidences
seem to point toward the conclusion that the
formation of the Mississippi embayment is a
tectonic incident closely related to the structural
history of the Gulf of Mexico which underwent
considerable epeirogenic movements during the
The idea of a Gulf of Mexico neutral plate was
introduced by Suess and substantiated by Schu-
chert who considered it to be the foreland of the
Antilles. Bornhauser accepted this neutral plate
and suggested that the northern border of the
plate may have formed the submarine plateau of
southeast Mississippi, at least during earlier Ter-
tiary. Deeper synclines separated this plateau


from the land masses on the northwest and north,
particularly during Midway-Wilcox time.
Bornhauser (op. cit., p. 709) stated:
In order to explain the progressive enlargement of the
southeast Mississippi plateau and the corresponding
shifting toward the north and northwest of its frontal
synclinal zones during the Eocene, the theory is advanced
that this plateau, together with the Gulf of Mexico
"plate," drifted in successive stages to the north as a
result of Tertiary orogenic movements in the Antilles.
A maximum penetration of the'plateau into the Missis-
sippi embayment was reached at the close of the Eocene
and early Oligocene periods, when it touched the northern
land masses. A breakdown of the southern part of this
plateau and a large part of the Gulf of Mexico followed
during the Oligocene and Miocene, forming the present
Gulf of Mexico. This downbreaking in connection with
the emergence of the embayment probably caused a change
in direction of the Gulf Coast geosyncline in south Loui-
siana. During the Eocene, the axis of this syncline
followed a southwest-northeast trend, with the Missis-
sippi embayment syncline forming its northeastern
extension. With the formation of the present Gulf of
Mexico during Oligocene and Miocene time, this axis was
diverted to a west-east trend.
Trask, Phleger, and Stetson (1947, pp. 460-461)
obtained sediments from the northwestern part of
the Gulf of Mexico during the 1946 expedition of
the Atlantis. In the central part of the Gulf,
where the depth of water exceeds 11,000 feet, two
distinctly different layers of sediment were found.
A thin top zone of globigerina was underlain, in
most cores, abruptly, by alternating clay and very
fine, well-sorted silt containing a cold water fauna.
In other cores, from the same depth, ripple marks
and crossbedding were found. Such conditions
suggest shallow-water deposition; and, to get such
conditions, it is necessary to assume either a rather
recent great depressing of the Gulf floor or an
equally great lowering of sea level. The other
alternate is to assume sufficient currents at depth
to cause sorting, ripple marks, and crossbedding.
Lowman (1949, pp. 1986-1993) believed that
the central part of the Gulf of Mexico might have
been epicontinental in character during Eocene
time. The evidence cited includes the wide extent
of the Eocene into the transverse embayments, the
gentle depositional slopes, the dominance of con-
tinental shelf faunas, and the character of the
sediments of the southeast Mississippi platform.
In contrast to the Eocene, the Upper Tertiary is
absent from the transverse embayments and has
continental-slope faces on relatively steep deposi-
tional slopes. Therefore, the Upper Tertiary sup-

ports a deep hole in the central part of the Gulf of
Mexico, as it is today, though not necessarily in
the same location.
Lowman did not believe the stratigraphic evi-
dence was conclusive that the Mississippi River
syncline subsided in response to load. He believed
some workers have used facies criteria instead of
planes of stratification in the isopach maps which
find "maxima under the delta in the Quaternary
and the Pliocene-Miocene" (op. cit., p. 1991).
Weaver (1950, p. 359) studied the continental
shelves of the Gulf of Mexico and decided that a
significant tectonic zone is at the outer edge of the
continental shelf. He concluded that the topo-
graphic contours on the continental slope are
really structural contours and that they exist in
sufficient number to indicate active tectonic
regional features. He proposed "the theory that
the Gulf of Mexico as a deep sea is young, and
that its present central great depth is due to
downfaulting." The most intense faulting is
indicated along the outer margin of the continental
shelf west of Florida and near Yucatan, but even
the more gentle continental slopes are considered
fault zones. No definite time of faulting was
given by Weaver.
Moody (1950) favored a single salt mass as the
source of the Gulf coast and Mexican domes and
suggested that it may extend across the Gulf of
Mexico into the Isthmus of Tehuantepec. If this
is true, the Gulf of Mexico was shallow enough to
allow salt deposition beyond the present continent
during the time of the deposition of the Eagle Mills
salt, which is Jurassic in the opinion of Moody,
although some writers place it in the Triassic or
Permian. He believed the Gulf of Mexico had
some downwarping during Upper Cretaceous; that
it began to take shape at the end of the Laramide
Revolution; and that it subsided, and maybe
formed the Mexican Basin, in post-Reynosa
(Pliocene) diastrophic movements. The finding
of Reynosa gravels in Florida at an elevation of
360 feet suggests a great change in sea level to
allow these gravels to be transported there. This
means a great post-Reynosa diastrophic movement
during which the west Florida shelf scarp and
possibly the Mexican Basin came into existence.
Eardley (1951b, p. 2236) stated that "the Gulf
of Mexico came into existence after the Appa-
lachian orogeny by subsidence." Much of the Gulf
is surrounded by the belt of late Paleozoic orogeny,


and sediments dating back to at least the Permian
are found in its marginal areas. Eardley believed
that the margins of the Gulf have had a near
balance between subsidence and deposition, while
subsidence has exceeded deposition in the central
Mexican Basin.
King (1951, p. 175) stated his belief that the
origin of the Gulf coast geosyncline was uncertain,
but he believed "that the geosyncline represents
an independent tectonic feature and perhaps a
new mobile belt in its early stage of development."
The theory of Weaver that fault scarps bound
the present central great deep of the Gulf received
additional support by Jordan (1951, p. 1991) who
described the escarpment off the panhandle of
Florida. This escarpment occurs in 700 to 900
fathoms of water, and the sea floor is offset 6,000
feet or more in some places. Comments on Jor-
dan's paper by Stetson (1951, p. 1993) confirmed
the findings of Jordan and noted that the escarp-
ment maintains about the same height and slope
southward along the west Florida shelf. Stetson
further commented that "from the overall picture
of the whole area, one gets the impression that
the bottom of the Gulf has foundered and that at
least this continental slope is due to a normal
fault" (idem.).
To date little exploration in the Gulf of Mexico
has had as its objective the determination of
major tectonic features. The cost of marine geo-
physical surveying and the drilling of offshore
wells are such that the tectonics of the Gulf must
be approached indirectly by using soundings and
bottom samples together with observations of the
shore features.
The topography of the Gulf of Mexico is too
scantily mapped to show the degree of develop-
ment of the different types of topography so far
known there.
As early as 1878 Agassiz (1878-79, p. 1) noted
two of the striking topographic features of the
Gulf, the great limestone banks: one west of
Florida and the other northward from the penin-
sula of Yucatan. In both cases the 100-fathom
line is somewhat parallel to the shore and forms
the inner edge of the steep slopes descending to
the Mexican Basin, which is another major fea-
ture of the Gulf. The varying development of
continental shelves and the irregular continental

slope with its escarpments, basins, knobs, and
troughs are also striking features of the Gulf of
The continental shelf forms an almost con-
tinuous terrace around the margin of the Gulf of
Mexico. The major breaks occur in the Straits
of Florida and the Yucatan Channel which form
outlets from the Gulf to the Atlantic Ocean and
Caribbean Sea, respectively.
The shelf is not an expressionless plain lacking
in interesting physiographic features as may be
suggested by some maps with a contour interval
too great to properly present the smaller features.
This terrace or shelf has numerous depressions,
troughs, ridges, minor knobs, coral heads, escarp-
ments, and two known submarine canyons.
The widest parts of the continental shelf in the
Gulf of Mexico lie off Texas and the peninsulas of
YucatAn and Florida. The shelf width varies
from 8 to 117 miles in the northern Gulf, the
maximum width being off western Florida. Other
shelf widths include: 40 miles off the southern tip
of Florida, 52 miles off the Isles of Dernieres,
Louisiana, 110 miles off the Sabine River mouth,
40 miles off the Rio Grande outlet, and 135 miles
off western and northern YucatAn.
The continental slope differs from place to
place not only in width and steepness but also in
physiographic features associated with it. The
continental slope, in general, constitutes one of
the great relief features of the earth. The edge
of the continental shelf is only very roughly paral-
lel to the shore line as is shown by the varying
width of the shelf. The continental slope varies
greatly in width with a minimum width west of
Florida and west and northwest of the YucatAn

The continental shelves of the Gulf of Mexico
seem to have a close geologic and physiographic
relationship with the adjacent land. Broad
shelves lie in front of broad coastal plains, and
narrow shelves lie between steep continental
slopes and rugged near-shore terrain.
There is no simple explanation of the origin of
the shelves and slopes, or of some of the features
of these provinces, that has gained wide accept-


In discussing continental shelves, Pratt (1947,
p. 661) observed that "modern investigations
have also confirmed Nansen's pioneer observation
that the inland portion of the continental shelf is
a surface of degradation." Umbgrove (1946,
p. 249) stated, "it appears that the history of the
shelf was rather complicated. Sedimentation,
abrasion, and denudation played their role. The
area was subjected to changes of sea-level and
movements of the bottom. Wind-waves and
tidal currents acted upon the sediments of the
shelf. The influence of each of these and still
more factors in the building of the submerged
part of the continental margin is still an open
question." He also believed that the landward
part of the shelf may have resulted from plana-
tion when the sea was some 300 feet lower than
at present.
Many workers believed that the topography
of the shelves resulted from subaerial erosion.
Dana (1863, p. 441) stated this was accomplished
by the elevating of the land. Long coast lines
would have to be uniformly elevated to such
heights that most geologists agree the hypothesis
has too many difficulties to be acceptable. The
lowering of sea level could also produce conditions
for subaerial erosion. Shepard and Emery (1941,
p. 154) found that the formation of Pleistocene
ice could account for lowering sea level 2,200
feet; Veatch and Smith (1939, p. 41) believed
sea level was lowered 12,000 feet and restored
in the last 25,000 years; Fisk (1944, p. 68) found
evidence for a drop of sea level of 400 to 450
feet; and Carsey (1950, p. 375) suggested that if
sea level was lowered 420 to 480 feet "the origin
of the shelves could be attributed'largely to wave
The irregularities of the bottom of the shelves
and the great valley-like notches along the out-
ward slopes of the shelves are also unsolved prob-
lems. Umbgrove (1946, p. 249) believed "the
phenomena of the continental margin are corre-
lated with other periodic events occurring in the
earth's crust and its substratum."
Daly (1936, p. 401) introduced the idea of
density currents or "bottom streams of sea water
containing mud in suspension and therefore tem-
porarily endowed with density greater than that
normal to the clean water overlying the respective
continental terraces. It is further supposed that

the conditions for the formation of such bottom
currents were specially developed at certain stages
of the Glacial Period . ." This heavy mass of
mud and water would naturally move into the
depressions on the continental shelf, and in places
it would flow over the margin of the shelf and
down the continental slope with accelerated mo-
tion and force.
A new hypothesis for the origin of continental
slopes and submarine canyons has been suggested
by Emery (1950, pp. 102-104). He proposed
that "thrusting along a shear plane at the con-
tinental margins may result in a temporary up-
bulging of the margins above sea level. During
the time of exposure erosion by streams should
have incised canyons which now, after isostatic
readjustment of the margins, constitute the widely
distributed submarine canyons. Known down-
warped peneplains below the surface of con-
tinental shelves may have been developed on the
bulged margins by long-continued erosion. The
margins may, thus, have served as sources of
some sediments now found on land and believed
to have been derived from a seaward direction."
Kuenen (1950, p. 497) adhered to the belief
that "the action of turbidity currents, especially
during the ice ages" cut the submarine canyons
along the edge of the shelf and slope of the
An examination of the maps of the topography
of the outer shelf and slope of the northern Gulf
of Mexico shows many features which suggest an
origin due to density currents and the deposition
of the mass of mud. Also, continental shelf fauna
dredged from the Mexican Basin may have been
transported from the shelf by turbidity currents.
Furthermore, these currents may have carried
sediment to the central Gulf and, therefore, aided
in developing the rather flat floor of the Mexican

Soundings in only a few areas of the Gulf are
adequate to permit the drawing of accurate maps
of the surface of the continental slope. More
information is available concerning the northern
Gulf; therefore, this area is discussed in some
detail starting with the Straits of Florida and
progressing in a counterclockwise direction.


The Florida Plateau includes not only the State
of Florida but an equally great or greater area
that lies submerged beneath water less than 50
fathoms deep and forms the Florida shelf (H.
Gunter, 1929, p. 41). This plateau has been in
existence since ancient time and is a part of the
Gulf of Mexico "plate" of Suess and Schuchert.
Its history includes submergence during Upper
Cretaceous, part of Oligocene, and Upper Miocene.
Since Miocene time uplift has continued, and
erosion has removed much of the once continuous
cover of Miocene sandy limestone. The Florida
Peninsula now has very little relief. It has a
wide continental shelf off its west coast, thus
demonstrating the physiographic similarity be-
tween the coastal plain and the adjacent con-
tinental shelf.
The 1947 expedition of the United States Coast
and Geodetic Survey ship Hydrographer in the
waters on the continental slope southwest of the
Apalachicola River, Florida, has been reported,
in part, by Jordan (1951, pp. 1978-1993). Many
new and interesting data have been secured in the
25,000-square-mile area of this report.
The greater part of the continental shelf west
of the peninsula of Florida is covered by about
40 fathoms of water, and the slope out to the
100-fathom contour is for the most part gradual.
The westward slope varies from 10 at the north
to 50 at the south end of the shelf.
In the 25- to 80-fathom depths, domes, ridges,
and troughs were discovered; escarpments and
knobs with a relief of more than 300 feet were
found in the 70- to 90-fathom depths. Most of
these features occur along the shelf margin.
Within the 400- to 1,760-fathom zone the con-
tinental slope contains a deep escarpment, faults,
and the terminus of the De Soto Canyon, as well
as domes and depressed areas.
The continental slope escarpment is of special
interest since it may materially aid in the ultimate
solution of the origin of the Gulf of Mexico.
Jordan (op. cit., p. 1991) noted a 350 gradient on
a 4,000-foot drop, contrasting with 10 gradients
or less above and below the escarpment. A ridge
30 miles long parallels the escarpment at 700 to
800 fathoms, and ridges and troughs with relief
up to 600 feet occur along the bottom of the
escarpment. The main escarpment undoubtedly

represents faulting, and some of the minor troughs
and ridges may have a like origin.
There can be little doubt that the Florida
Plateau has been faulted along its western edge,
but the faulting is difficult to date. Schuchert
believed this faulting was due to the inbreaking
of the Gulf of Mexico "plate" and that it probably
began in the Upper Cretaceous. However, Weaver
(1950, p. 359) believed "that the Gulf of Mexico
as a deep sea is young" and therefore the faulting
must have occurred at a much more recent date.
The Mississippi River brings to its mouth a
daily load of sediment in the order of 2 million
tons. This material has permitted the Mississippi
to build its delta out on the continental shelf with
the overlapping delta reaching within some 10
miles of the landward edge of the continental
slope. It might be expected that a deep trough
would exist in the outer edge of the continental
shelf in front of the Mississippi River, but such
is not the case.
An ancient, deeply buried channel is found
about 30 miles southwest of the passes of the
Mississippi River. Shepard (1948, p. 213) stated
that this trough, which has a depth of 1,800 feet,
is the only major indentation in the shelf margin
in the Gulf of Mexico and that the trough-head
penetrates the shelf for nearly 30 miles. The
sides are steep, and the flat floor is filled with
loosely consolidated sediments. The canyon has
been traced out on the continental slope to a depth
of 900 fathoms before it becomes merged in the
irregularities of the slope.
A second trough, called De Soto Canyon, has
been discovered off the Apalachicola River of
southwestern Florida. Shepard (1948, p. 179,
fig. 65) reproduced a map of this trough or canyon
as contoured by H. W. Murray of the United
States Coast and Geodetic Survey. This map
shows a series of depressions, some with relief
exceeding 20 fathoms, along the bottom of the
trough and a few depressions along the sides of
the trough. This canyon is shown in Jordan's
map (1951, p. 1982, fig. 2) of the continental
slope. The canyon has a relief of about 600 feet,
heads near the 240-fathom contour, and terminates
near the 500-fathom contour. Stetson (1951,
p. 1993) stated that cores of the steepest walls of
the canyon showed sediment and no bed rock.


Upwellings of clay, locally known as mud-
lumps, occur near the mouths of the Mississippi
River passes and have never been reported from
any other delta. These mudlumps have been the
subject of written discussion for more than a
century, but only a few writers have attempted a
scientific explanation of them. The most recent
study has been made by Morgan (1951) in
conjunction with the Corps of Engineers at New
Mudlumps and mudlump islands have at-
tracted much attention since they may have mud
cliffs with a relief of up to 10 feet in an area where
the average relief is usually 2 feet or less.
Most mudlumps have central cores of fine-
grained plastic clay surrounded and sometimes
capped by irregularly stratified layers of clay
and silt. The upwelling of the clay core usually
produces fissures and faults with vertical dis-
placements resulting in central grabens. The
stratified layers dip away from the islands, often
forming doubly plunging anticlinal structures.
Local cones along the faults and fissures are
formed by the discharge of mud, gas, and salt
Morgan ibidd.) believed that the "formation of
new lumps and rejuvenation of old lumps occurs
as a direct result of excessive sedimentation at the
river mouths" and "the deforming force which
caused mudlump uplift is the static pressure of the
sedimentary mass continually being dumped
beyond the mouths of the passes."
The continental shelf off Louisiana and Texas
is somewhat uniform and has a gentle slope to
about the 50-fathom contour. From this point
the slope increases to the 70-fathom line where it
has an increase in gradient to the 100-fathom
depth. Some increase in slope is noted beyond the
100-fathom line, but the bottom becomes so
irregular that the true slope becomes obscure.
Probably the chief characteristic of the con-
tinental slope of the northern Gulf is the hum-
mocky topography. Shepard (1937, p. 1350)
found 26 topographic features off the coast of
Louisiana some of which had a relief of several
hundred feet. Charts revealed that the belt
of domes can be traced definitely for 180 miles
west and southwest of the Mississippi submarine
trough. More recent data show that some of the

depressions are 2,000 feet deep, and some of the
hills have a relief of at least 2,500 feet.
Carsey (1950, p. 376) found 164 topographic
features along the shelf off the coast of Louisiana
and Texas. An area of apparent concentration
of these features is shown in figure 16. However,
it is probable that there are many somewhat
similar features elsewhere on the continental shelf
and slope. They seem to be most prevalent in
the area between the 100- and 750-fathom con-
It is particularly interesting to note that no
stream patterns have been found other than the
troughs on the margins of the slope off the Mis-
sissippi Delta and the Apalachicola River (Shepard
1948, p. 178).
Price (1951, p. 32) observed that the "rugged
topography of the northwestern shelf-margin or
slope seems to contain dislocated segments of
submarine canyons" which differ in late history
from the canyons along the less rugged slope to
the east. This suggests that the front edge of
the shelf was faulted down in slices as it was
built out into the Gulf.
Available maps of the topography of the Gulf
bottom vary widely in their representation of the
physiographic features. The amount of time as
well as the number of soundings available influence
the choice of the contour interval. Thus, the
Treadwell (1949) map of the continental slope of
the northwestern Gulf of Mexico, contour interval
of 50 fathoms, shows a great number of closed
basins and knobs between 910 and 950 W. Long.
and 270 to 280 N. Lat. Also, there are suggestions
of drainage patterns that are not evident in the
map by Shepard (1948, p. 178, fig. 64) with a con-
tour interval of 100 fathoms. Some of these
differences may be due to the contour interval,
but some may also be the result of additional
data and the choice of the cartographer when
more than one interpretation of the data exists.
All available maps of the continental slope of
this region show the same general characteristics
of the Gulf bottom: a very irregular, hummocky,
knob and basin topography.
Minor near-shore features of ridge and trough
were noted by Kindle (1936, pp. 866-867) along
the Louisiana coast. He waded across a 1,500-
foot traverse and found ridges whose crests were
10 feet wide and separated by troughs from 60 to
90 feet wide. The same traverse was repeated


2 days later, and while the ridges were free of mud,
the depressions were filled with several inches of
mud. Therefore, the whole character of the
local bottom was changed in 48 hours. This
shows the futility of making sweeping conclusions
from only a few data, especially in the shore zone.

Too few data are available on the topography
adjacent to Mexico to make a detailed study of
either the continental shelf or slope of this region.
However, some generalizations may be made
from the scanty sounding data and geological
maps of the adjacent land.
Mountain ranges, trending northeast-southwest,
have been mapped 90 and 110 miles east of the
mouth of the Rio Grande. The range nearer
the coast has a known relief of 2,750 feet with a
summit reached at a depth of 540 fathoms and
the other range has a known relief of 3,810 feet
with a summit at a depth of 839 fathoms.
Due east of Tampico a mountain range, with a
bearing of N. 65-700 E., extends some 40 miles
and has a relief of 5,800 feet with a summit rising
to within 33 feet of the surface.
Along the extreme western edge of the Gulf of
Mexico, south of Tampico, the continental shelf
is narrow, and the adjacent coastal plain is also
narrow, being locally practically absent. Tertiary
and later igneous rocks occur in the Misantla-
Japala area, northwest of Veracruz, and in the
Alvarado-El Paso area, south of Veracruz. Some
of the highest peaks of Mexico occur just northwest
of Veracruz. Lava flows cover much of the
near-shore land area and locally form 1,000-foot
cliffs at or very near the shore. South of Vera-
cruz other smaller cones are very near the coast.
While local narrow beaches are formed and break
the surface continuity of igneous rocks, undoubt-
edly the offshore irregular topography is due to
underwater outcropping of these igneous rocks.
Practically all of the Yucatan Peninsula forms
a broad coastal plain. This peninsula tilts north-
westward and passes under the Gulf to form a
continental shelf averaging over 125 miles in
width. The shelf terminates abruptly to the
west and north, and the topographic contours
along its edge are undoubtedly also structural
contours and represent faulting.

There is within the Gulf of Mexico, but not
centrally situated, a large triangular area with
deeps exceeding 2,000 fathoms. It lies north-
west of the Campeche Banks approximately
between 22' and 25' N. Lat. and 890 and 950 W.
Long. Regarding this area, Hilgard is quoted by
Agassiz (1888, p. 101) as follows: "The large sub-
marine plateau below the depth of 12,000 feet has
received the name of the 'Sigsbee Deep', in
honour of its discoverer." Since the "depth of
the basin does not attain 3,000 fathoms, it is not
a 'deep' in the Murray sense, but it is an enclosed,
distinctive basin, for which Sigsbee's name may
appropriately be retained" (Vaughan 1940, p. 66).
More recently, however, the name "Sigsbee
Deep" has been restricted to the deepest measure-
ment in the basin, and the name "Mexican
Basin" is used here for the broad, enclosed basin.
The bottom of the Mexican Basin is very flat,
especially when contrasted with the continental
slope of the Gulf. The depths range from 2,000
to 2,070 fathoms over the deepest part of the
basin. The bottom rises rather uniformly to the
shore in the west in a distance of 180 miles, but
the northern slope is more gentle and apparently
more irregular in its distance of 300 miles. The
slopes toward Florida and the Yucatan Peninsula
are broken by abrupt changes which undoubtedly
represent faults in the bottom.
One of the most prominent mounds in the Gulf
is found in the northeast portion of the Mexican
Basin. It has a relief exceeding 890 fathoms, a
possible width of 60 miles, and its top is encoun-
tered at a depth of 916 fathoms.



The near-shore sediments, at least, should be
expected to be closely related to the sediments of
the adjacent coastal plain except near the mouths
of major rivers. Much study has been given
samples obtained from wells and outcrops in the
area surrounding the Gulf of Mexico. Such
studies have shown that each formation varies
widely in its composition as it curves around the
Gulf from Florida to Mexico.


The Tertiary outcrops in the Gulf Coastal
Plain include thick continental sandy and lignitic
deposits and thinner marine sands and clays.
Down-dip from the outcrops, drilling has shown
that the Tertiary continental deposits pass into
brackish water and near-shore marine deposits.
According to Lowman (1949, p. 1941), rapid
transgressions and slow regressions produced
cyclical effects in the sediments with most of the
sediments deposited during the regressive phases
of the cycles. Farther down-dip or seaward the
sediments change to a succession of offshore
marine clays.
In general, the Gulf coastal area may be di-
vided into intergrading depositional areas as fol-
lows: Rio Grande Embayment, East Texas Basin,
Mississippi Embayment, the Gulf coastal region
of Alabama, Georgia, and North Florida, and
South Florida. The amount of rainfall on the
land area surrounding the ancient Gulf may have
been the chief factor in determining the contem-
poraneous deposition of many sedimentary de-
posits ranging from anhydrite and salt to shales
and limestones. Rolshausen (1947, p. 5) sug-
gested that during pre-Eagle Ford Cretaceous
time, west of the Appalachian Mountains, rivers
entering the Gulf from the north and northeast
supplied the major load of sediments. East of the
mountains the rivers entered the Gulf from the
northwest and west. After Eagle Ford time,
rivers entering the Gulf from the west, and prob-
ably draining the western part of the present
Mississippi basin, were the chief source of sedi-
ments. The Rio Grande may have been the major
source of sediments from the late Cretaceous
through early Miocene time with the Mississippi
River contributing little sediment during that
The sediments brought to the Gulf of Mexico
are probably not carried far from shore. Parr
(1935, p. 62) showed that at a point only 70 miles
out in front of the mouth of the Mississippi River
the water has "transparency practically equal to
the clearest ocean water known." It is a gen-
erally accepted fact that water discharged from
the Mississippi River is carried almost entirely to
the west and that it stays relatively close to the
shore. Clarke (1938, p. 91) found that measure-
ments of transparency supported this conclusion.
Geyer (1950b, p. 100) noted that the salinity of

the offshore coastal waters of Louisiana west of
the delta was largely controlled by the discharge
of fresh water from the Mississippi River and the
westward moving littoral current. The observa-
tions of the writer between 1948 and 1951 confirm
the westward movement of the fresh water enter-
ing the Gulf from the Mississippi River.
Cogen (1940, p. 2101) examined samples of sed-
iments taken from the bottom of the Gulf near
the mouth of the Rio Grande and concluded that
the present bottom sediments of this region were
carried into the Gulf by the Rio Grande.
Bullard (1942, pp. 1021-1043) showed that each
of the principal rivers carries a distinct suite of
heavy minerals. The Rio Grande sand shows its
primary source by the predominance of basaltic
hornblende and pyroxene and only 30 percent of
the stable minerals such as garnet, rutile, zircon,
tourmaline, and staurolite in the heavy mineral
residue. The Nueces, San Antonio, Brazos,
Trinity, and Sabine Rivers, draining areas of sed-
imentary rocks, have little hornblende and pyrox-
ene and a high content of stable minerals. Since
the Colorado River derives its load from both
primary and secondary rocks, its suite of heavy
minerals is over half green hornblende. North-
ward from the Rio Grande the beach of Padre
Island contains the Rio Grande suite of heavy
minerals, but the influence of the other rivers is
clearly shown by an increased ratio of more stable
minerals in the samples farther north in Texas.
The sediments of the Coastal Plain do not end
at the shore but extend out under the sea, and "if
the basement surface on which they rest con-
tinues to slope uniformly, the mass of sediments
must increase in thickness at least as far as the
edge of the continental shelf, beyond which they
should thin out rapidly as they merge into the
oozes of the ocean depths" (Stephenson 1926, p.
Land derived sediments are not being moved in
a "continuous sheet of detritus all the way from
the beach to the continental slope" (Daly 1942,
p. 100). If this were true, much of the con-
tinental shelf would be some fathoms shallower
than at present. With continuing deposition the
sea would become more shallow, and wave and
current action would push the sediments nearer
the edge of the shelf. When the sediments
reached the edge of the continental shelf and a
profile of equilibrium was attained, the shelf sur-


face would have been raised several fathoms.
Therefore, it appears that a profile of equilibrium
does not exist on the outer part of broad Gulf of
Mexico continental shelves.
Sediments carried to the Gulf of Mexico largely
remain in that body of water rather than being
carried into the Atlantic. The Gulf of Mexico is
of no importance to the deep-water circulation of
the Atlantic Ocean (Kuenen 1950, p. 44). The
unnamed current that becomes the Florida cur-
rent is the major current of the Gulf, and "it is
essentially a direct continuation of the current
through the Yucatan Channel" (Sverdrup, John-
son, and Fleming, 1942, p. 642). The waters of
the Gulf mainly form independent eddies and are
only to a small extent drawn into the Straits of
Florida. These eddies appear to be semiper-
manent features with their locations determined
by the contours of the coast and the configuration
of the bottom (idem., p. 641).1

The Coast Survey instituted a series of investi-
gations on physical problems of the deep sea in
1846, with emphasis on the Gulf Stream. In
1850, L. Agassiz made an extended biological sur-
vey of the Florida reefs, and in 1867, Pourtales
and Mitchell began a more systematic deep-sea
exploration. Dredging between Florida and Cuba
in 1868 reached depths of 850 fathoms, and the
bottom samples obtained showed a closer relation-
ship to the cretaceous fauna rather than to or-
ganisms of the adjacent shores.
Commander Howell, U. S. N., began a system-
atic exploration of the Gulf of Mexico in 1872,
starting in the shallow waters along the west
coast of Florida, and the work was continued by
Lieutenant Commander Sigsbee in 1875-78, using
the United States Coast Survey steamer Blake.
The specimens of bottom deposits were sent to
John Murray of the Challenger for examination,
and he published the results in 1885 (Murray, pp.
51-61). Excerpts from his original description
are as follows:
In all the deeper deposits in the Gulf of Mexico and
Strait of Florida, the crystalline mineral particles are very
small, rarely exceeding one-tenth of a millimeter in diam-
eter. They consist principally of small rounded grains of
quartz, with fragments of felspars, mica, hornblende,
3 For a detailed discussion of circulation of water in the Gulf of Mexico
see article by D. F. Leipper, Physical Oceanography of the Gulf of Mexico,
in this book, pp. 119-137.

augite, magnetite, and rarely tourmaline. In a few places
there were fragments of pumice, and glauconitic particles
were occasionally noticed. The mineral particles and fine
clayey matter appear to be almost wholly derived from
North American rivers.
The carbonate of lime in the deposits of these regions is
mostly made up of the shells of pelagic Foraminifera and
Mollusks. In depths greater than 2,000 fathoms the
Pteropod and Heteropod shells appear to be nearly, if not
quite, absent-the carbonate of lime then consisting of
the shells of pelagic Foraminifera; in less depths the Ptero-
pod and Heteropod shells are present, and in depths vary-
ing from 200 to 500 fathoms they make up the bulk of the
deposits in many places. In several of the deposits, where
the percentage of carbonate of lime is very high, the whole
has a very chalk-like appearance; it appears, indeed, as if
it were in the process of transformation to true chalk.
The siliceous organisms consist of Radiolarians and
Sponge spicules, with a few Diatoms, but these seldom
make up more than three or four percent of the whole
A study of the United States Coast and Geo-
detic Survey maps of the continental shelf ad-
jacent to Louisiana shows many different mate-
rials forming the Gulf bottom such as sands, muds,
clays, shells, and local reefs. These represent the
surface of the Gulf floor, and little is known about
the material even immediately below the surface.
Some borings have been made in the erection of
the platforms required for petroleum exploration,
but these platforms are all located approximately
within the first 30 miles off shore. The wells
drilled from these offshore structures have yielded
no known information of the surface formations.
Likewise, crews making geophysical surveys in
the Gulf are not interested in the surface or near-
surface formations (Willey 1948, p. 3).
Trowbridge (1927, p. 148) stated that the United
States Coast and Geodetic Survey obtained 600
bottom samples in 1921 and that their map of
1926 included the results of this work.

According to Trask, Phleger, and Stetson
(1947, p. 460) sediments in the Gulf of Mexico
have changed in relatively recent time. During
the 1947 expedition of the Atlantis, more than 600
cores were taken along 19 lines perpendicular
to the Texas and Louisiana coast, crossing both
the continental platform and the continental
slope and continuing into the depths of the
Gulf. The complete results of this expedition
have not been published to date, but some data
were discussed by Phleger (1950). It was found


that sediments off shore were remarkably uni-
form. Out to a distance of some 40 miles from
shore a combination of fine sand and coarse silt
with an average diameter of 100 microns was
found; this material was extremely well sorted.
On the outer shelf the sediments were much finer,
the average diameter being about 1 micron, and
they were poorly sorted. In water over 11,000
feet deep in the central part of the Gulf foramini-
feral ooze at the surface was underlain, beginning
at 2 feet depth, by alternating clay, silt, and sand,
the silt and sand being extremely well sorted.
A core taken in the Mexican Basin in 1947 is
of unusual interest. Trask, Phleger, and Stetson
(1947, p. 461) reported that:
The upper foraminiferal zone, 50 cm. in thickness, is
characterized by a subtropical planktonic fauna . .
Between depths of 50 and 68 cm. in a zone of red clay or
red mud, the fauna is transitional between cold and
warm water faunas. Between depths of 74 and 78.5
cm., at the top of the zone of banded clay and silt, the
fauna is definitely sub-Arctic . Between 78.5 cm. and
125 cm., the fauna is cold-water in type but is warmer
than that between 74 and 78.5 cm.; and from 125 to 128
cm., at the bottom of the core, the fauna is definitely
Trask (1948, p. 683) mentioned that ice-age
deposits showing crossbedding or ripple marks
were found in the coarse plastics of two cores taken
in the central Gulf of Mexico. In other cores
"well-sorted sand zones, one and three feet,
respectively, were encountered at depths of more
than three feet beneath the surface of the sedi-
ments. Such deposits, if hardened into rock and
formed in a geosyncline, would be taken as
compatible with the idea of shallow-water depo-
sition. Yet they were encountered in 11,000
feet of water."
The Fish and Wildlife Service of the United
States Department of the Interior, cooperating
with the Agricultural and Mechanical College
of Texas, is making a systematic survey of the
Gulf of Mexico. Much of the physical ocean-
ography is being done by the Texas A. and M.
Department of Oceanography, and the Depart-
ment of Geology is cooperating in the study of
Gulf problems of marine geology. Samples of
sediments obtained early in 1952 are now being
The major sedimentary provinces of the Gulf
are shown on the map in figure 16. The basic

data for this map were collected from many
sources, including the publications of Agassiz,
Carsey, Gunter, Kindle, Lowman, Murray, Phleg-
er, Price, Shepard, Stetson, Trask, and Weaver,
and by personal communications from individuals
principally W. A. Price, Department of Ocean-
ography, Agricultural and Mechanical College of
Texas. Unfortunately, the data resulting from
some 600 cores taken from the Atlantis in 1946
are not yet available. Also, the systematic
exploration of the Gulf now in progress will
provide many bottom samples from the whole
Gulf area, and these data will make possible
more detailed sediment maps in the future.
The recent sediments are divided into lithologi-
cal units which form somewhat indefinite zones
parallel to the coast and extending outward on
the continental shelf. In general, sands and
shales predominate from Florida west and south
to Cabo Rojo, Mexico, while limestone forms a
wide platform west and north of the Yucatan
Peninsula and west of Florida.

Modern calcareous sediments were thought by
Agassiz (1888, p. 286) to cover the continental
shelf on the west side of Florida. The charts of
this area show "sand and shells" and are therefore
deceiving. Samples from this region that were
examined by Shepard (1932, p. 1021) "were lacking
in quartz-sand and the use of sand as a textural
term seemed questionable." Little sediment goes
to the Gulf in streams from the Florida Peninsula,
and the shore deposits consist largely of calcium
carbonate secreted by organisms. Even the
Apalachicola River does not discharge an appre.-
ciable amount of clay and silt. However, some
quartz sand is found relatively near shore from
Mississippi eastward across Alabama and the
panhandle and near shore along the northern part
of the west coast of Florida. Also, recently, num-
erous sand bars have been found on the northern
part of the continental shelf west of the Florida
The area off shore from Alabama and the pan-
handle of Florida has detrital sediments which
show the influence of the southern Appalachians.
These sediments contain an abundance of ilmenite,
staurolite, kyanite, zircon, tourmaline, and si]li-
manite, and only minor amounts of magneti e,







FIGURE 16.-Sedimentary provinces of the Gulf of Mexico. Data compiled from many sources.




I -


amphiboles, pyroxenes, leucoxene, and hematite
(Goldstein 1942, p. 81).
Most of the continental shelf west of the penin-
sula of Florida is hard rock, chiefly limestone, but
a thin veneer of detrital sediment is present in
local areas and fills some of the shelf depressions.
Stetson (1951, p. 1993) obtained two specimens of
hard limestone and a specimen of soft, chalky
limestone from this shelf by using a steel rock
dredge after core tubes were damaged by the
hard rock.
The Florida Keys include a 200-mile chain of
islands curving southwestward along the edge of
the Florida Straits from Biscayne Key to Key
West and the Dry Tortugas. The northeastern
keys are old coral reefs, but the ones to the south-
west are remnants of a former island. Vaughan
(1910, p. 119) stated that silica, as sand, is abun-
dant in Biscayne Bay but decreases to the south-
west as calcium carbonate becomes more abundant
near the living coral reefs. The calcium carbonate
occurs "as a flocculent sediment or ooze over
practically the entire region from the lower portion
of Biscayne Bay to the gulf end of Florida Bay."
However, Trask (1932, pp. 166-172) found that
the basins in Florida Bay have coarser sediments
than the compact marl rims. The basin sediments
are "shell breccia embedded in a matrix of marl."
The recent work of Lowman (1951, pp. 234-235)
provided the basis of division of the limestone
banks west of Florida. He found that the white
sands of the Pensacola beaches extended seaward
to the depth of 20 fathoms and that the sands were
free of mud and were highly fossiliferous, with
Mollusca and Foraminifera being the most
common forms.
A second zone, extending out to 40 fathoms, was
found to contain many algae, forams, pelecypods,
brachiopods, bryozoans, and cup corals. The
Foraminifera showed a definite faunal break at
about 75 fathoms which Lowman (idem., p. 235)
suggested may be the result of changes in turbidity
and light penetration in the clear water. In the
more turbid waters west of the Mississippi Delta
a faunal break was noted at 45 to 50 fathoms.
Bush (1951, pp. 102, 106) reported on a rock
specimen obtained by dredging in the Straits of
Florida, south of the American Shoals, at a depth
of 375 fathoms. This rock, apparently broken
from the ocean floor, was very fossiliferous and
was correlated with the Chipola formation (lower

Miocene) of northern Florida. This suggests "the
dip and continuance of the lower Miocene strata
from the Florida Peninsula under the Straits of
Florida toward Cuba" (idem., p. 106).
Between the Florida Straits and Cuba and also
west of the continental shelf the bottom sediments
are calcareous muds, and westward they grade
into blue mud and Globigerina ooze.
Most of the coarse sediment of the Mississippi
River is deposited near its mouth, but Trowbridge
(1930, p. 892) noted that outside the Southwest
Pass of the river, coarser sediment occurred on
knolls in 30 fathoms of water. This coarser sedi-
ment apparently was not derived from the present
Mississippi River under present conditions. The
concentration of coarse sediments may have
resulted from the removal of the finer sediments by
winnowing due to stronger currents over the knolls.
Shaw (1916, p. 107) stated that fine sand, silt,
and clay were accumulating on the Gulf of Mexico
floor immediately beyond the mouth of the Mis-
sissippi River very near where they were dropped
by the river. He contrasted this with conditions
on the west Gulf coast where the sediments
brought to the Gulf by streams were being re-
worked by waves and currents yet not carried far
from the mouths of the streams.
Mud and sand are recorded on many maps on
either side and adjacent to the Mississippi River,
but sampling by the writer shows silt and "mud"
to be greatly in excess of sand. Westward from
the delta there is a clay-silt zone with some sand
and shells. Dark gray to black "mud" is present
in most of the lagoons.
Kellogg (1905, p. 34) and many others, including
the writer, have observed the hard crust that
develops during the winter. This crust is only
an inch or two thick and is underlain by soft silt
and "mud." The clay and finest particles have
probably been removed by winnowing during the
winter when the Mississippi River is in a low stage
and therefore carrying a minimum sediment load.
The very high ratios of organic matter to
chlorophyll which occur near the mouth of the
Mississippi River "indicate large quantities of
organic detritus. The ratios fall so rapidly as
one proceeds out in the Gulf that it seems likely
that practically all the organic detritus of fresh
water origin is removed from the surface water


before it gets more than ten or fifteen miles from
the mouth of the river" (Riley 1937, p. 91).
It is noted in figure 16 that the blue mud province
extends northward to near the mouths of the
Mississippi River. Since the front of the delta
overlaps the continental shelf nearly to its outer
edge, the sediments of the deeper Gulf approach
the tip of the delta. Likewise, the Globigerina
zone lies close to the land at the delta.
The numerous submerged hills rising above the
sea floor near the outer edge of the continental
shelf materially influence the local sediments.
Trask, Phleger, and Stetson (1947, p. 461) noted
that the slopes of these hills are covered with
"silty, calcareous sand, and the tops by round
Lithothamnium balls and little or no sandy material
. . while the adjacent flat continental shelf is
underlain by sandy silt." The Lithothamnium
balls, diameters up to 10 cm., must have been
moved by the water since they seemed to be alive
on all sides. Corals, similar to those common in
the West Indies, were dredged with the Litho-
thamnium balls. These areas are included in
figure 16 in the patches of coral lying along 280 N.
lat. between 910 and 95 W. long.
The dominant sediment on the continental
shelf along the Louisiana coast west of the Mis-
issippi Delta is mud and sand. Locally, near
shore, sand predominates to form a sand beach
and shore zone. The common, heavy minerals
of these sediments are amphiboles, epidote,
dolomite, pyroxene, ilmenite, and biotite.
Near the outer edge of the shelf and particularly
on the continental slope there are many topo-
graphic features of considerable relief. Carsey
(1950, pp. 377-379) noted 164 such topographic
features along the Louisiana-Texas slope and
made a study of their density distribution accord-
ing to their degree of relief. This study showed
that two-thirds of these features have a relief of
less than 300 feet, while some rise 600 feet above
the floor of the Gulf.
The sediments on the tops and flanks of topo-
graphic features, having a relief in hundreds of
feet, may be greatly different from those on the
ocean floor only a short horizontal distance away.
Corals have been dredged from the tops of a few
of these knobs or domes, but little is known con-
cerning the deposits on the flanks. The finer

sediments may have been washed from the tops
of these knobs to settle on the Gulf floor around
the base. More detailed sounding and dredging
in this area are needed to adequately study the
sedimentology of the area.
Over a 50-year period numerous "oil spots" or
"seeps" have been reported as having been ob-
served in the northwest Gulf of Mexico. The
locations of these seeps are noted on the map
(fig. 16), and it is seen that they are concentrated
between 91-930 W. and 26030'-27030' N. Since
several of these "oil spots" were said to be several
scores of miles long, their origin, although un-
known, is of interest.
The rivers of Texas are not heavily laden with
sediment, except during flood stages, and for this
reason it can be assumed that the Recent alluvial
deposits found on the continental shelf will not be
of great thickness. Also, these streams have
little velocity as they cross the wide coastal plain,
and only fine-grained mechanical sediments are
carried to the Gulf. This has been shown by
Storm (1945, p. 1313) in a series of samples col-
lected in the Gulf out from Corpus Christi, Texas.
Beyond the near-shore fine material sands with
0.21 millimeter average diameter occurred in a
narrow belt about 12 miles from shore. Twenty
miles from shore the grain size had decreased to
an average of 0.03 millimeter, while 30 miles from
shore it had increased to an average of 0.18 milli-
meter. From 30 to 40 miles off shore the grain
size remained about the same, but beyond 40
miles it decreased again. These variations seem
to be closely associated with the currents.
In 1948 Mattison (p. 77-78) found a string of
coral heads off the Brazos River mouth about 8
miles off shore. They occur in 6 to 8 fathoms of
water and have a relief of 2 to 3 fathoms. They
have been seen by fishermen who describe them as
having the appearance of sunken icebergs but
having sea fans and other marine growth forming
solid coral or white limestone in an area of black
mud. Coral heads occur approximately along
the 40-fathom line in front of Corpus Christi,
Texas, and Smith (1948, p. 82) noted that six of
these heads were reached within a foot or two of
31 fathoms of water.
Along most of the east coast of Mexico from
Texas to the Gulf of Campeche the charts show


"sand" near shore and "mud" off shore, showing
an outward gradation of sediments.
Agassiz (1878, p. 1) found the fauna of the
Yucatan Bank to be identical with that of the
Florida Bank, being characterized by the same
species of echinoderms, mollusks, crustaceans,
corals, and fishes.
From Tampico southward beyond Veracruz
volcanic rocks are found near shore, and possibly
igneous rocks will be found in the adjacent Gulf
waters. Therefore, the sediments in this area
should be somewhat different from those off
southern coastal Texas and from those associated
with the limestone of the Campeche Banks to the
east. The coastal plain is exceedingly narrow
locally, and the beach sands give way to near-
shore patches of coral. In many places mud
extends out on the shelf beyond the coral.
The beach sands along the west and north
shores of the Yucatan Peninsula do not spread
far from shore except locally where sand and mud
are found out to the edge of the shelf. To the
southwest of the peninsula the sand becomes
mixed with near-shore coral patches.
Numerous local patches of coral occur over the
Campeche Banks, and in other places the bottom
is very similar to the Florida Bank. The hard
limestone is locally covered with a thin veneer of
detrital sediments. The Globigerina ooze prov-
ince joins the Campeche Banks apparently with
the blue mud absent between these calcareous
Corals are common at the outer edge of the
narrow shelf off the northern coast of Cuba.
Beyond these corals the Florida Straits contain
calcareous mud with the exception of a local area
to the northwest of Cuba where pteropod ooze
has been found.
A bottom sample taken in 20 fathoms of water
at 2425' N. lat. and 82'26' W. long. was sub-
jected to a chemical and spectrographic analysis.
Also, use was made of electrolytic separation in a
mercury cathode cell to concentrate the trace
elements. No unusual trace elements were found,
and the common elements were in approximately
the same abundance as has been determined by
others who analyzed the skeletal material of
organisms which contribute to sediment formation.

The upper surface of the floor in the deepest
part of the Gulf consists of foraminiferal ooze.
The few available cores show the underlying sedi-
ment to be clay, silt, and sand, which is cross-
bedded and ripple-marked in some cores. The
origin of this detrital material is unknown as is
also the origin of the basin forming the Gulf.
Turbidity currents may have brought much sedi-
ment to the central Gulf. Such an origin is
further suggested by the presence of continental-
shelf Foraminifera in the Mexican Basin sediments.
Agassiz (1888, pp. 280-282) quoted Murray who
observed that the globigerine and pteropod ooze
found in the central Gulf of Mexico differed
materially from that found in the oceanic basins.
Diatoms, radiolarians, and sponge spicules com-
prise the siliceous organisms but represent only a
small percentage of the bottom deposits. Fish oto-
liths were found at depths from 392 to 1,568 fath-
oms. The globigerine ooze was found to extend
northward to the Mississippi River slope where it
was replaced by dark, rich muds containing "a
number of interesting forms of annelids, mollusks,
ophiurous and sea-urchins, characteristic of the
continental Gulf slope, and typical of mud
deposits" (idem., p. 282).

The Gulf of Mexico, with a surface area of
615,000 square miles, offers many rewards for
research in geology, biology, and oceanography.
Continued drilling at the extreme margins of the
Gulf may produce new local data as greater depths
are reached by the drill, but much of the search
must be made far from shore. To date most of the
geophysical prospecting has been in the very shoal
areas where present methods of development may
apply. The use of geophysics to study the tec-
tonics of the Gulf largely lies in the future.
Therefore, it seems that present aid in solving the
many problems of the Gulf of Mexico must come
from the oceanographer who can give other
scientists new data from soundings, bottom
samples, and the physical characteristics of the
While the time and manner of the origin of the
Gulf basin are still undetermined, present evidence
favors the existence of a shallow Gulf, the "plate"
of Suess and Schuchert. Assuming that Llanoria


extended into the Gulf, its submergence may have
been completed by late Jurassic time, thus pro-
viding for the invasion by the Cretaceous seas.
Post-Cretaceous downwarping tilted the Creta-
ceous deposits Gulfward, but, in general, the Gulf
remained a shallow sea during most of the early
Tertiary. During late Tertiary the basin of the
Gulf further subsided, possibly both by down-
warping and faulting along the basin margins.
The escarpment along the west edge of the
Florida shelf (Jordan 1951, pp. 1978-1993) un-
doubtedly has its origin in faulting, and similar
conditions seem to exist at the outer edge of the
Campeche Banks. Other areas along the con-
tinental slope suggest fault scarps. The basin of
the Gulf may well have been deeper than the
present 12,425 feet, with post-mid-Tertiary sedi-
ments filling the basin to its present depth.
There is no reason to believe that the irregu-
larities of the continental slope are confined to the
local areas which have had detailed study, and
further hydrographic work should produce data of
great scientific value.
Interest in the Gulf has been greatly accelerated
in the past decade, and there is much evidence
that this interest will continue, which should
result in the eventual solution of many of the
present riddles of the Gulf of Mexico.


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