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State of Florida
Department of Natural Resources
Elton J. Gissendanner, Executive Director




Division of Resource Management
Charles W. Hendry, Jr., Director




Florida Geological Survey
Steve R. Windham, Chief









Open File Report 9

Alum Bluff
Liberty County, Florida

by

Kenneth M. Campbell


Florida Geological Survey
Tallahassee, Florida
1985
































3 1262 04643 6374



t9





SCIENCE
LIBRARY





OPE/E FILE REPORT

ALUM BLUFF
LIBERTY COUNTY, FLORIDA

Walt Schmidt
Florida Geological Survey
903 W. Tennessee Street
Tallahassee, Florida 32304

LOCATION

Alum Bluff is one of the best natural geologic exposures in

the state of Florida. It is located about two miles north-

northwest of Bristol, in Liberty County, Florida. The bluff

occurs along the east bank of the Apalachicola River i, Townslip lN,

Range 8W, Section 24, in the '1E and SE quarters (Figure 1).

The Nature Conservancy owns the Bluff area and adjacent

land. Their land is protected by fence and lck'ed cates.

Permission to enter can be obtained :y contactinq thei'- Bristol

Office at P. O. Box 789, Bristol, Florida 3232L, or calling (9D04)

893-4153. Land access to the bluff area can be obtained by -0oin3

1.4 miles north of the intersectiron nt state routes 12 azi 20 in

Bristol, to the entrance of Skyland Ranch on the left (west).

Travel this dirt road .2 mile where the Nature Conservancy gate

will be encountered. Pass gate and follow the dirt road 2.7

miles to the Alum Bluff overlook (see Figure 1). Road condition

may vary depending on the amount of rain recently received.

Normally the sands are very loose and high centers occur in ihe

road. Pickup trucks and vans should nave no trouble, however a

small car with low clearance may have.


Florida Bureau of Geology Libr:iry
903 W. Tennessee St.
Tallahassee, FL 32304







The bluff is quite steep and the fossiliferous horizons are

near the bottom.. It is best to follow the bluff edge south until

you reach a small drainage 3eprossion and descend from there. In

summer the temperature and humidity can be very high. It is

recommended to carry water along if you plan on being more than

an hour or two.

The bluff can also be reached from the river by boat. There

is a public Launch about one mile upstream from the Route 20

bri.lge. This is accessible from Br-.;tol on the east side of the

river. The bluff is about three tnJles uo river from the boat

launch.

BACKGROUND

The middle to Late Tertiary deposits of the Florida

PanhandLe have been known since the late 1800's. They have "eein

described on numerous occasions and have received the moot atten-

tion from paleontologists adrrActed by their well preserved

mollusk assemblages (predominately Noogene). Alum Bluff was

first described by Langdon in 1889. Since that time other

authors have described or named these units primarily based on

their fossil assemblages. This location has been one of the pri-

mary outcrops used to establish the stratigraphic, paleoenviron-

mental and geologic history of the Florida Panhandle.

The sediments exposed at Alum Bluff include in acending

order: the Chipola Formation; the Hawthorn Formation; the

Jackson Bluff Formation; an unnamed sandy clay interval; an unnamed

clayey sand interval; and a unit composed of the Citronelle

Formation and reworked "terrace sands" figure e 2). This section


W-







The bluff is quite steep and the fossiliferous horizons are

near the bottom.. It is best to follow the bluff edge south until

you reach a small drainage 3eprossion and descend from there. In

summer the temperature and humidity can be very high. It is

recommended to carry water along if you plan on being more than

an hour or two.

The bluff can also be reached from the river by boat. There

is a public Launch about one mile upstream from the Route 20

bri.lge. This is accessible from Br-.;tol on the east side of the

river. The bluff is about three tnJles uo river from the boat

launch.

BACKGROUND

The middle to Late Tertiary deposits of the Florida

PanhandLe have been known since the late 1800's. They have "eein

described on numerous occasions and have received the moot atten-

tion from paleontologists adrrActed by their well preserved

mollusk assemblages (predominately Noogene). Alum Bluff was

first described by Langdon in 1889. Since that time other

authors have described or named these units primarily based on

their fossil assemblages. This location has been one of the pri-

mary outcrops used to establish the stratigraphic, paleoenviron-

mental and geologic history of the Florida Panhandle.

The sediments exposed at Alum Bluff include in acending

order: the Chipola Formation; the Hawthorn Formation; the

Jackson Bluff Formation; an unnamed sandy clay interval; an unnamed

clayey sand interval; and a unit composed of the Citronelle

Formation and reworked "terrace sands" figure e 2). This section


W-







has been described often by geologists and paleontologists, a few

of the more complete descriptions include: Dall and Harris (1892);

Dall and Stanley-Brown (1894); Maury (1902); Matson and Clapp

(1909); Gardner (1926-1944); Cooke (1945); Rainwater et al.

(1945); Puri (1953); Dubar and Beardsley (1961); Puri and Vernon

(1964); Akers (1972); Banks and Hunter (1973); Huddlestun (197:);

and Schmidt (1983).


FORMATIONS DISCUSSION

Chipola Formation The name Chipola Formation was sqiggesred

by Burns in 1889 (in Dall and Harris 1892). He discovered. and

made large collections from shell beds exposed on the Chipola and

Apalachicola Rivers. Dall and Stanley-Brown (1394) visited the

area a few years later and called the formation the Chipola shell

marl. Matson and Clapp (1909) included these beds as a member in

their Alum Bluff Formation, and Gardner (1926) later promlr.-o::d the

member to a formation. In 1953, Puri referred to the Chi.pcl as

a faces of the Alum Bluff Stage; then with Vernon (Purj and

.-Vernon 1964), they redefined it as a formation once again.

Fossils identified from the Chipola Formation include

mollusks, benthic and planktonic foraminifera, ostrocods, corals,

and calcareous nannofossils. Numerous authors have described the

fauna. A summary of these references can be found in Schmidtit a.d

Clark (1980, p. 38). Planktonic foraminifera and calcareous

nannofossils were used by Gibson (1967), Akers (1972) and

Huddlestun (1976) to estimate the age of the sediments. It has

been assigned to a Burdigalian age (late Er.aly Miocene).







has been described often by geologists and paleontologists, a few

of the more complete descriptions include: Dall and Harris (1892);

Dall and Stanley-Brown (1894); Maury (1902); Matson and Clapp

(1909); Gardner (1926-1944); Cooke (1945); Rainwater et al.

(1945); Puri (1953); Dubar and Beardsley (1961); Puri and Vernon

(1964); Akers (1972); Banks and Hunter (1973); Huddlestun (197:);

and Schmidt (1983).


FORMATIONS DISCUSSION

Chipola Formation The name Chipola Formation was sqiggesred

by Burns in 1889 (in Dall and Harris 1892). He discovered. and

made large collections from shell beds exposed on the Chipola and

Apalachicola Rivers. Dall and Stanley-Brown (1394) visited the

area a few years later and called the formation the Chipola shell

marl. Matson and Clapp (1909) included these beds as a member in

their Alum Bluff Formation, and Gardner (1926) later promlr.-o::d the

member to a formation. In 1953, Puri referred to the Chi.pcl as

a faces of the Alum Bluff Stage; then with Vernon (Purj and

.-Vernon 1964), they redefined it as a formation once again.

Fossils identified from the Chipola Formation include

mollusks, benthic and planktonic foraminifera, ostrocods, corals,

and calcareous nannofossils. Numerous authors have described the

fauna. A summary of these references can be found in Schmidtit a.d

Clark (1980, p. 38). Planktonic foraminifera and calcareous

nannofossils were used by Gibson (1967), Akers (1972) and

Huddlestun (1976) to estimate the age of the sediments. It has

been assigned to a Burdigalian age (late Er.aly Miocene).







Hawthorn Formation Dall and Harris (1892) in discussing

the phosphoritic sediments being quarried near Hawthorne in

AL chiai County, Florida assigned them the name "Hawthorne Beds".

Mar-on and Clapp (1909) Later designated this unit the Hawthorn

Formation. Pirkle (1956; and Pirkle et al. 1965) designated the

Devil's Millhopper sink in Atachua County and Brooks Sink in

Bradford County as cotype localities.

The Hawthorn Formation has been mapped into the Florida

Pnhanhandle by Cooke and Mossom (1929): Puri (1953); Vernon and

Purl (1956); and others. It is considered Middle Miocene in age

and thought to represent a deltaic or a pro-deltaic environment

in the vicinity.

Jackson Bluff Formation Purl and Vernon (1954) are cre-

lited with naming the Jackson Bluff Formation. They combined the

Ecphora and Cancellaria biofacies because both are exposed at

Jackson Bluff in Leon County, Florida. For a more complete

historical record of nomeclatural changes leading up to current

usage see Schmidt and Clark, (1990, p. 41-58). They include

references citing paleontological descriptions and age correla-

tions. Fossils from the Jackson Bluff include: numerous mullusk

shells; corals; ostracods; echiniods; bryozoa; barnacles; benthic

and planktonic foraminifera; and calcareous nannofossils, among

others. Based on planktonic foraminifera, it has been concluded

that the Jackson Bluff was deposited in the Middle to earliest

Late Pliocene (Akers, 1972: Huddlestun 1976).


UI'







Dubar and Beardsley (1961) reported on the paleoecology of

the Jackson Bluff Formation deposits from the Alum Bluff site.

They concluded that the sediments were deposited in the inner

neritic zone in less than 8 fathoms of waters. The shell bed

they state; "was deposited in normal open shelf marine water

during a minor transgression of the sea".

Sandy Clays and Clayey Sands These sediments are respon-

sible for the name of this local outcrop. "From the

efflorescence of ferrous sulphate arises the name Alum Bluff"

(Langdon, 1889 p. 322). This interval has been called the

aluminouss clay" by several authors. Dubar and Beardsley (1961)

have suggested that this interval was deposited in stagnant

possibly lagoonal conditions. There is a absence of marine

fossils and the sulphurous odor and carbonaceous nature of the

sediments also lead to this conclusion.

Citronelle Formation The Citronelle Formation was name

by Matson (1916, p. 168) for outcrops near the town of Citronelle,

in southwestern Alabama. In northwestern Florida it consists of

fluvial, cross-bedded sands, gravels and clays, and post-

depositional limonite. In the Alum Bluff vicinity this unit con-

sists of cross-bedded quartz sands, sandy more massive clay

beds, clay pebbles, and brown to red iron stained bedded clayey

sands. The age of the Citronelle has been difficult to ascertain

due to the lack of fossil material (Isphording and Flowers,

1983). More recent reworking and other similar deltaic deposits

make correlation and differentiation time consuming and

questionable. Recent workers based on plant remains and stra-

tigraphic position have put a Late Pliocene-Pleistocene age on

these sediments.







REFERENCES


Akers, W. IH., 1972 Planktonic Foraminifera and Biostratigraphy of
Some Neogene Formations, Northern Florida and Atlantic
Coastal Plain: Tulan^Studies in Geol. and Paleo. V. 9, 140 p.

Banks, J. E., and Hunter, M. E., 1973, Post-Tampa, Pre-Chipola
Sediments Exposed in Liberty, Gadsden, Leon, and Wakulla
Counties, Florida: Trans. Gulf Coast Assoc. Geol. Soc.
V. 23, p. 355-36.3.

Cooke, C. Wythe, 1945, Geology of Florida: Florida State.
Geological Survey Bull. 29, 342 p.

,and Mossom, Start, 1929, Geology of Florida:
Florida Sate Geol. Survey 20th Ann. Report, 1927-1928,
p. 29-227.

Dall, William Harris, and Harris, Gilbert D., 1982, The Neocene
of North America: U. S. Geol. Survey Bull. 84, 349 p.

and Stanley-Brown, Joseph, 1894, Cenozoic
Geology along the Apalachicola River: Bull. Geol. Soc.
America V. 5, p. 157.

DuBar, Jules, R., and Beardsley, Donald W., 1961, Paleoecology of
the Choctawhatchee Deposits (Late Miocene) at Alum Bluff,
Florida: Southeastern Geology, V. 2, p. 155-189.

Gardner, Julia A., 1926-1944, The Molluscan Fauna of the Alum
Bluff Group of Florida: U. S. Geol. Survey Prof. Paper 142,
pts. 1-4, 1926; pt. 5, 1928; pt. 6, 1937; pt. 7, 1944.

Gibson, T. G., 1967, Stratigraphy and Paleoenvironment of the
Phos hate Miocene Stata of North Carolina: Geol. Soc.
Amer ca, Bull., V. 78, p. 631-650.

Huddlestun, Paul F., 1976, The Neogene Stratigraphy of the
Central Florida Panhandle: Unsubmitted Ph.D.Dissertation
Florida State University, Geology Department.

Isphording, W. C., and Flowers, G. C., 1983, Differentiation of
Unfossiliferous Clastic Sediments: Solutions From the Southern
Position of the Alabama-Mississippi Coastal Plain; Tulane
Studies in Geology and Paleontology, V. 17, No. 3., p. 59-83.

Langdon, D. W. Jr., 1889, Some Florida Miocene: American Journal
Science 3rd Series V. 38, p. 322.

Matson, G. C., 1916, The Pliocene Citronelle Formation of the
Gulf Coastal Plain: U. S. Geol. Survey Prof. Paper 98,
p. 16 7-192.


I '








,and Clapp, F. G., 1909, A Preliminary Report of
the Geology of Florida, with Special Reference to the
Stratigraphy .Florida State Geological Survey, Secon.i
Annual Report, p. 25-173.

Maury, Carlotta J., 1902, A Comparison of the Oligocene of
Western Europe and the Southern United States: Bull. Am.
Paleontology, V. 3, No. 15, 94 p.

Pirkle, E. C., 1956, The Hawthorn and Alachua formation of
Alachua County, Florida: Quart. Jour. Florida Acad. of
Sci., V. 19, p. 197-240.

Yoho, W. H., and Allen, A. J., 1965, Hawthorn,
Bone Valley, and Citronelle Sediments of Florida: Quat.
Jour. Florida Acad. Sci., V. 28, No. 1, p. 7-47.

Puri, Harbans S., 1953, Contribution to the Study of the Miocene
of the Florida Panhandle: Florida State Geological Survey
Bull. 36, 345 p.

and Vernon, R. 0., 1964, Summary of the Geology
of Florida and a Guidebook to the Classic Exposures: FlriFda
State Geological Survey, Special Publication 5 Revised, 312 p.

Rainwater, E. H., Herring, D. G., and Ericson, D. B., 1945,
Western Florida: Southeastern Geological Society, Third
Field Trip, Nov. 9, and 10th, 1945, 93 p.

Schmidt, Walter, 1983, Neogene Stratigraphy and Geologic History,
Apalachicola Embayment, Florida: Ph.D. Dissertation Florjaaa
State University, Geology Department, 233 p.

__, and Clark, Murlene Wiggs, 1980, Geology of Bay
County, Florida: Florida Bureau of Geology, Bulletin 57, 96 p.

Vernon, R. 0. and Puri, H. S., 1956, A Summary of the Geology of
Panhandle Florida and Guidebook to the Surtace Exposures:
Geol. Soc. Am. Southeastern Section Field Trip, March 24,
1945, 83 p.









'Fi(ure 1 Part of the Bristol Quadrangle (1945)
Best route to Alum Bluff ----


Fiqure 2 Geologic Section at Alum Bluff, (Revised after
Dubar and Beardsley, 1961, p. 165).


Il~aa -




---- ---sl"-P-&~I ~ -` ^9~w~s~a rcP







ALUM BLUFF STRATIGRAPHIC DESCRIPTION


Cirtonelte Formation and Terrace Sands Thickness (ft.)

Unconsolidated to poorly consolidated, tan
to yellow orange and red brown, poorly
sorted, mottled and cross-bedded, clayey,
fine to gravel size quartz sands. ........... 48


Clayey Sands

Poorly consolidated, red, yellow and gray
clayey, variegated quartz sands ............ 15


Sanldy Clays

"Aluminous Clay" c.amcl by Dall (1894).
Poor to moderately consolidated, greenish
gray, micaceous, limoiltic, sandy clays. .... 55


Jackson Bluff Formation

Moderately consolidated, green gray to
bluish gray, glauconitic, phosphoritic,
mollusk shell rich, sandy clay and clayey
sands. This is type locality of the
"Ecphora facess. ... ......................... 15


Hawthorn Formation

Moderately consolidated, gray to yellow and
white, variegated, crosi-bedded, and lami-
nated, clayey sands. TVis interval con--
tains fossil Leaves, wood fragments and
carbonized logs. .............. . . .... 20


Chipola Formation

The lowermost beds exposed at Alum Bluff.
Moderately consolidated, tan-brown to
yellow, calcareous sands with numerous
mollusk shells and an excellent microfauna.
The base of the unit is not exposed. The
Chipola forms the prominent ledge along
the river. ........ .......... ............... 10


Total Thickness Approximately ................


133






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----*^B1l-~-~-^-~--Ji


SHELL MARL


SAND WITH CLAY
WOOD COMMON


LENSES,


SANDY
BIOCALCARENITE AND
ALCAREOUS SANDS


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ARGILLACEOUS SAND
MOLDS OF MOLLUSKS


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RIVER