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STATE OF FLORIDA
DEPARTMENT OF ENVIRONMENTAL PROTECTION
Virginia B. Wetherell, Secretary






DIVISION OF ADMINISTRATIVE AND TECHNICAL SERVICES
Mimi Drew, Director of Technical Services






FLORIDA GEOLOGICAL SURVEY
Walter Schmidt, State Geologist and Chief





OPEN FILE REPORT 67





TOPOGRAPHIC MAPS: USEFUL TOOLS FOR THE FLORIDA FOSSIL HUNTER

By

Frank R. Rupert


FLORIDA GEOLOGICAL SURVEY

Tallahassee
1995






UNIVERSITY OF FLOiA I RARIES


















@2-

0.c 'Z



SCIENCE
LIBRARY










Topographic Maps

Useful tools for the Florida fossil hunter
by Frank R. Rupert, P.G. 149


Maps are important tools to anyone working in the
field, especially in unfamiliar terrain. One of the
more useful maps for the avocational and
professional paleontologist alike is the topographic
map. Topographic maps have many applications in
Florida. In this article we will examine some
topographic map basics and discuss their use by
fossil hunters.

A topographic map is a map illustrating the
topography or shape of the land surface.
Topographic maps show the locations and form of
hills, valleys, streams, and other features as well as
many man-made landmarks. They illustrate the
shape and elevation of surface features by the use
of contour lines. Contour lines are imaginary lines
(they exist on paper only) which connect points of
equal elevation on the earth's surface. They provide
a means of displaying three-dimensional information
on a two-dimensional sheet of paper. The vertical
difference in elevation between adjacent contour
lines is called the contour interval.
Consider the illustration in Figure 1. As shown
in the upper portion, this figure illustrates a section
of hilly coastline bisected by a flat stream valley,


and featuring a flat, sandy spit enclosing a small
bay. If we were to go to this site and actually paint
horizontal lines of equal elevation on the hills and
valley floor at each 20 feet interval above sea level
in elevation, then look down on the scene from
above, we would see a view similar to the map in
the lower part of the figure. The lower portion of
Figure 1 is a topographic map of this section of
coast. Notice several things about the map in this
figure which hold true of all topographic maps:

1) Contour lines appear closely packed together on
the steep bluff face on the left. In the flat valley
and on the gently-sloping hill top above the bluff,
they are widely-spaced. This is because on steep
slopes elevation increases occur with greater
frequency per unit of horizontal map distance and
thus appear closer together. To visualize this,
imagine a yardstick with the inch markings
representing short, parallel contour lines; looking
straight down at a yardstick lying flat on the
ground, the inch marks appear spaced uniformly at
1 inch apart. Now slowly lift one end of the
yardstick to form an imaginary slope face while still
looking down at it and watch the inch marks appear
to move closer together as you increase the slope of
the stick.

2) The land slope, or the ratio of vertical to
horizontal distance, may be determined from
topographic maps. Slope is usually expressed as a
ratio (ie: 1:100) or as a percent (1 percent). The
slope between points A and B on Figure 1, for
example may be calculated by dividing the elevation
increase (vertical distance) from A to B by the
horizontal distance between the points. In this case
the vertical distance is the elevation at B (100 feet)
minus the elevation at A (about 50 feet, as it is
halfway between the 40 and 60 feet contour lines),
which equals 50 feet. The horizontal distance
between A and B is measured from the map bar
scale at the bottom of the map, and is
approximately 3500 feet. Therefore, the slope is
50/3500 or 1:70, or .014 (1.4 percent).

3) Contour lines do not intersect, cross, or branch.
They may touch or coincide only on very steep


Figure 1. Perspective view and topographic map
of a section of hilly coastline (Yon, 1972).


I









Topographic maps


slopes (and this is commonly due to the thickness of
the printed contour lines only on vertical slopes
would the lines truly coincide).

4) Contour lines form a "V" pointing upstream (or up-
gradient) in stream valleys or drainage rivulets. In
closely spaced stream valleys, such as those shown
on the hill on the right in Figure 1, a series of W"
shapes may result; the stream valley "V's" point
towards the top of the hill, the down slope-pointed
"V's" are the intervening noses of higher ground
between streams.

5) The contour interval is constant on any map.
Every fourth or fifth contour line is labeled with their
elevation for reference; on actual topographic maps,
the contour lines representing every 50 feet of
elevation are commonly labeled, while those in
between are not. Spot elevations are sometimes
shown for specific points on the map. All elevations
are relative to mean sea level, which is taken to be ""
foot elevation.

6) Wide rivers and streams are defined by parallel
lines approximating their mean width; narrow streams
and creeks are shown with single blue lines;
coastlines and lake shores are shown with a single
unlabeled line.

7) Local man made structures, including buildings,
roads, and bridges are commonly shown. Some of
these symbols are shown in Figure 2.

On actual topographic maps, many of the
different features are delineated in color; contours
lines are brown, water is blue, roads are printed in
red or black, and structures are printed in black.
Cities and other large areas of manmade disturbance
are usually printed in either purple or gray shading.
Areas of vegetation are shaded green. The maps
illustrated on the following pages of this article are, by
necessity, printed in black and white. Some of the
inherent "readability" is therefore lost.
Topographic maps are prepared today largely
from composite aerial photographs, with field
checking where needed, and provide some of the
most accurate local detail available. Therefore they
are a useful tool for locating possible new sites,
planning fossil-hunting expeditions, and as references
in accurately documenting the location of known
fossil sites. Topographic maps can be especially
useful in locating areas where fossiliferous strata may
be exposed, either naturally by stream erosion and
karst activity, or by man's excavations.


Topographic maps in Florida
The entire state of Florida has been mapped by
the U.S. Geological Survey in 7.5 minute topographic
quadrangles. These maps are termed seven and a
half minute quadrangles because each map covers a
rectangular area of land surface equal to 7.5 minutes
of longitude in width (about 7.5 miles) and 7.5
minutes of latitude in height (8.5 miles). Latitude and
longitude tick marks are provided along the margins
of topographic maps. One thousand and thirty seven
7.5 minute quadrangles are required to cover the
entire state. The actual paper quadrangle maps are
about 23 inches wide by 27 inches high. This size
allows a standard scale for the map of 1:24,000 (one
unit of map distance in inches, feet, or millimeters,
etc., equals 24,000 of the same units on the surface
of the earth). The fractional scale and a bar scale of
distance is part of the information printed at the
bottom of the map. The direction of true north is
always towards the top of the map. Magnetic north,
which may be a few degrees east or west of true
north, is also indicated on the map.
Earlier topographic maps, generally dating from
prior to 1940, were based on 15 minute quadrangles.
These covered an area equivalent to four of the 7.5
minute maps, and had a scale of 1:62,500. The
larger, modem 7.5 minute maps generally provide
better detail, although the older maps can often be
used to document historical changes in land features
or urban sprawl.
Today, each topographic quadrangle map is
given a specific name, usually based on some local
geographic feature (i.e., Tallahassee Quadrangle,
Okeechobee NW Quadrangle, etc.). Certain of the
maps, especially those in highly-populated areas, are
updated every several years to show the expansion of
civilization. Others in more remote locations may not
have been updated since the original mapping in the
1940s. A handy index (see Figure 3) showing the
locations and names of all 1,037 quadrangle maps
covering the state is printed by the United States
Geological Survey.

Some practical examples of topographic map
usage for the fossil hunter
In some regions of Florida, topographic maps
may prove extremely useful to the avocational
paleontologist in search of fossiliferous exposures.
They are an aid in locating mines, quarries, sinks and
incised streams, all features which might expose
otherwise buried fossiliferous strata. Topographic
maps may also serve to document the location of
sites to revisit. Following are examples of
topographic maps from several different areas of









TOPOGRAPHIC MAP SYMBOLS
VARIATIONS WILL BE FOUND ON OLDER MAPS


Hard surface, heavy duty road, four'or more lanes ......
Hard surface, heavy duty road, two or three lanes .......
Hard surface, medium duty road, four or more lanes ..m..
Hard surface, medium duty road, two or three lanes ....
Improved light duty road ............................
Unimproved dirt road and trail ................. .... .-.-I-I-I-I
Dual highway, dividing strip 25 feet or less............ ..
Dual highway, dividing strip exceeding 25 feet.........
Road under construction. ........................ .


Railroad, single track and multiple track .............
Railroads in juxtaposition ...........................
Narrow gage, single track and multiple track........... _ "
Railroad in street and carline ....................... .
Bridge, road and railroad .......................... .
Drawbridge, road and railroad ......................
Footbridge.................................... . ..-- -
Tunnel, road and railroad.................. .........
Overpass and underpass ................. . .
I 1 I I
Important small masonry or earth dam ................
Dam with lock ..... ...... ........... ...
Dam with road ......................... ..........
Canal with lock......................... ........ . .


Buildings (dwelling, place of employment, etc.).......... ln -
School, church, and cemetery. ....................... .iT !.m i
Buildings (barn, warehouse, etc.)....................o..
Power transmission line.....................................
Telephone line, pipeline, etc. (labeled as to type)........- --. .
Wells other than water (labeled as to type)............. oOil ....o Gas
Tanks; oil, water, etc. (labeled as to type).............. 0 OWater
Located or landmark object; windmill................ ............
Open pit, mine, or quarry; prospect.................. :x......... x
Shaft and tunnel.entrance........... ............... a .......... T


Horizontal and vertical control station:
Tablet, spirit level elevation ...................... BMA5653
Other recoverable mark, spirit level elevation......... A 5455
Horizontal control station: tablet, vertical angle elevation VABMA9519
Any recoverable mark,vertical angle or checked elevation A3775
Vertical control station: tablet, spirit level elevation..... BM X957
Other recoverable mark, spirit level elevation........ X954

Checked spot elevation ........................ ..... x47
SUnchecked spot elevation and water elevation .......... xs657.... .eo


Boundary, national ................................
State .................... ...........
County, parish, municipio ........................
Civil township, precinct, town, barrio............... _-
Incorporated city, village, town, hamlet.............._. .-.- ._-
Reservation, national or state ..................... .
Small perk, cemetery, airport, etc. ..........................
Land grant..................................
Township or range line, United States land survey .....
Township or range line, approximate location .......... ........
Section line, United States land survey ..............
Section line, approximate location ........................ _..
Township line, not United States land survey .....................................
Section line, not United States land survey ............. ..............
Section corner, found and indicated .................. ........ +
Boundary monument: land grant and other............o ........ o
United States mineral or location monument.... ....... ,


Index contour .... Intermediate contour.. _
Supplementary contour Depression contours .._--
Fill.............. Cut.................

Levee............ ....... ............. Levee with road .........
Mine dump.......... ,,. Wash...............

Tailings ............... Tailings pond ....... .-

Strip mine........... Distorted surface.....

Sand area........... Gravel beach....... -'


Perennial streams ....
Elevated aqueduct .... _.
Water well and spring. o.......
Small rapids..........
Large rapids.........
Intermittent lake..... ...---'
Foreshore flat.......
Sounding, depth curve. ~51*tI
Exposed wreck....... .;*I Z


Intermittent streams.. Z -
Aqueduct tunnel..... .,.. _
Disappearing stream..
Small falls .......... -
Large falls .......
Dry lake............... ---
Rock or coral reef....
"'''4 "a
Piling or dolphin. . .
Sunken wreck........ -. i


Rock, bare or awash; dangerous to navigation .......... -


Marsh (swamp)....... Submerged marsh ...

Wooded-marsh...... .- Manigrove ........... -.

Woods or brushwood.. I Orchard... ......... I

Vineyard............. .... Scrub........ ......

foundation area........ -- Urban area ..........


Figure 2. Some topographic map symbols







ALL IAPS S OWN THIS INrEX
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Portion of Index Map shown full size.
Each box in the grid represents the
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Map name and year of publication
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NOTE: This figure Is a
reduced version of the full
size, 22" X 32" index map. It is
presented here for illustration
purposes only. A full size
index map may be ordered
free from the U.S. Geological
Survey. See address at the
end of this article.


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Florida. We will discuss these maps and the
information they contain for the fossil hunter.
Hopefully, the reader can apply some of these ideas
to his or her own unique collecting areas.

Alum Bluff Florida's classic geologic exposure:
Alum Bluff is a 120 feet high bluff on the east
bank of the Apalachicola River, about two and a half
miles north of Bristol in Liberty County. The actively-
eroding bluff was cut by the eastward advance of the
river, and exposes Middle Miocene to Recent
sediments. It is by far the most spectacular geologic
exposure in Florida, and the area is also treasured by
botanists for its unique living plant communities. The
bluff and associated land is presently owned and
managed by the Nature Conservancy.
Alum Bluff is illustrated on the Bristol topographic
quadrangle map (see Figure 4). Its steepness is
readily apparent by the very closely spaced, 10-foot
contour lines which represent the bluff face. On this
map, the contour lines representing multiples of 50
feet of elevation are thicker in width and selected lines
are labeled with the appropriate elevation. The finer
lines between labeled lines represent successive 10-
foot elevation lines. As an example, the second fine
contour line above the 50 feet line would represent 70
feet in elevation.
Alum Bluff rises from the edge of the river, which
lies at approximately 50 feet above mean sea level
(MSL), to 170 feet above MSL at its crest. The land
surface plateau above the bluff is rolling, sandy terrain
reaching a maximum elevation of nearly 200 feet
above MSL. Note the 195 feet spot elevation, just
southeast of the bluff, near the junction of the two dirt
roads shown by parallel dashed lines. Immediately
north and south of Alum Bluff are more bluffs, with
less-steep faces, bordering the flat, swampy
floodplain of the Apalachicola River. Extending
eastward from the bluffs are several deeply incised
creeks, such as Little Sweetwater Creek and Kelly
Branch. Each is fed by smaller streams branching off
the main creek. These feeder streams originate at the
base of rounded, amphitheater-like features called
steepheads. Steepheads form when the small spring
seeps feeding the creeks undercut overlying strata,
causing slumping of the overburden into the stream.
The steepheads migrate laterally by on-going
undercutting and slumping, thus lengthening the
streams in some preferential directions. These
spectacular features are impressively deep, and may
also contain unique floral and faunal communities.
Alum Bluff has been a premiere fossil collecting
site in the Florida panhandle because of its unique
geologic position and because it is actively being cut


in an eastward direction by a meander loop of the
Apalachicola River. It exposes a variety of sediments,
including Middle Miocene Chipola Formation,
containing abundant fossil mollusks and corals, and
Alum Bluff Group equivalent strata, containing both
vertebrate and plant fossils. Fresh strata is generally
exposed by each flood stage of the river, and
vegetation has little opportunity to become
established. The bluffs both north and south of Alum
Bluff are of nearly equivalent elevations, but are not
actively eroded, are less steep (as indicated by the
wider-spaced contour lines), and are more heavily
vegetated as a result. However, fossiliferous strata
could be found by the ambitious collector at
elevations similar to those in Alum Bluff in the nearby
bluffs and steephead streams. It would likely require
digging, as slumped sediment and organic debris
commonly cover the adjacent bluffs and stream valley
walls.

The Haile quarries works of man in typical
limestone terrain:
The small "hamlet" of Haile, Florida, is situated
about 3 miles northeast of Newberry, in western
Alachua County. Eocene limestone lies close to the
surface in this region, where it is covered only by
variably thick quartz sands and clayey sands. Mining
of this high purity limerock has occurred throughout
this region for years.
The Haile area is shown on the Newberry
topographic quadrangle map, a portion of which is
illustrated in Figure 5. The surrounding terrain shows
a typical contour line pattern of numerous closed
loops of various sizes and shapes. Some have short
perpendicular lines or ticks extending from the
contour line inward towards the center of the loop.
These tick marks are called hachures, and are used
to indicate depressions in the land surface. They
form a visual method of differentiating contour lines
which designate decreasing elevation from nearby
lines of increasing elevation. In effect, they allow the
viewer to tell whether a feature comprised of a series
of unlabeled, concentric contour lines is a hill or a
bowl-shaped depression.
The terrain around Haile is underlain by shallow
limestone bedrock. Dissolution by slightly acidic
ground water has produced a highly irregular bedrock
surface pocked with sinkholes, solution pipes, and
intervening pinnacles. This terrain type is known as
karst. Much of the limestone surface roughness is
masked by the thin blanket of relict marine sands
covering the region. These sands tend to smooth
and in-fill the karst depressions. Even so, many of
the karst features are expressed at the surface as









SCALE 1 24000
0 : MILE
1000 0 100, 2000 3000 4000 5000 6000 1000 FEE'
S5 0 1 KILOMETEr

Bar scale for all maps.


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variably-shaped depressions, caused by settling of
the overburden sands as the underlying limestone
collapses or dissolves.
The proximity of high-purity limestone to the
surface in this area has historically made limestone
mining economically feasible near Haile. Quarries are
open pit mines, generally excavated to some practical
depth determined by the capabilities of the excavating
equipment as well as the ability of mechanical pumps
to keep the pit free of encroaching ground water.
The large inactive quarries in the Haile area appear
on the topographic map as water filled pits of various
unnatural shapes. Mining areas are commonly
denoted by the crossed pick symbol. Quarries active
at the date of mapping may appear dry on the map.
But once abandoned, they typically re-fill with ground
water unless they are fortuitously perched above the
local water table. Lying near the pits are small, steep,
oval hills (see Figure 5). These represent man made
piles of overburden and mine tailings. Some of those
illustrated may attain heights of thirty feet.
Quarries provide the fossil hunter access to
numerous invertebrate fossils and occasional
vertebrate remains. The Eocene Ocala Limestone,
which is mined locally for roadbase material, contains
large foraminifera as well as abundant mollusks and
echinoids. The limestone may rarely contain Eocene
whale material as well. More commonly, younger
vertebrate fossils are found in the undifferentiated
sinkhole fill sediments, which are exposed in cross-
section in the mine walls. Most active mines turn
amateur collectors away for liability reasons, but the
above-water portions and spoil piles of abandoned
mines can provide excellent hunting sites. Old mines,
as well as deep sinks which may potentially expose
limestone may easily be located on topographic
maps. Many are located near roads, allowing easy
access. Today, more than ever, it is important to
remember our fossil hunting ethics. Be sure to obtain
current landowner permission before entering any
mines, old or new. It is also wise to use caution
around potentially unstable sheer mine walls, rock
piles, and water-filled pits.

Gainesville There's Miocene in those ditches:
In contrast to the karst plain terrain near Haile,
the city of Gainesville is largely situated atop stream-
dissected clayey sand hills at the southwestern edge
of the Northern Highlands geomorphic zone. Figure
6 is a portion of the Gainesville East topographic


map. The extent of the city is indicated by the gray
shading, and many of the streets are labeled on the
map for reference. Clayey fossiliferous sediments of
the Miocene Hawthorn Group form the core of the
hilly terrain, which attains elevations of about 185 feet
above mean sea level, and which is punctuated by
deeply incised creek channels. Because the clayey
sands form a protective layer over the underlying
limestone in much of eastern Gainesville, ground
water has not had the opportunity to form the
extensive karst features seen at Haile. Occasional
sinks do occur here however, and generally form
deep, circular depressions as they perforate the
Hawthorn sediments. The Devil's Millhopper, a large,
deep sinkhole located in northern Gainesville, is a
classic example. West of the University of Florida
campus, the Hawthorn sediments thin, and numerous
karst features are more evident.
The Hawthorn Group sediments lie near or at the
surface in the Gainesville area. As a result, the
sinkholes, road cuts, and stream channels which cut
down into the Hawthorn offer the fossil hunter the
best local collecting opportunities. Among the more
common finds are shark teeth and dugong rib pieces,
but more exotic finds, such as Miocene long-beaked
dolphin are also known from Gainesville proper. The
topographic map allows the aspiring collector to
accurately locate the deeper stream ravines which
likely expose fossiliferous sediments. Potential sites
are indicated by the closely-spaced contour lines
along Hogtown Creek and its tributaries, just
northwest of the U of F campus. Although it is
sometimes difficult in urban settings to find access to
such creeks, it may be possible to enter the
streambed at a road crossing. In doing so,
remember to be cognizant of other's property rights.

Shell Creek a southern Florida invertebrate site:
As a final example of topographic map
usefulness, we will look at a typical area in
southwestern Florida. Brown (1988) describes a fossil
shell site in western Charlotte County along the
appropriately named Shell Creek. The stretch of
stream he mentions is illustrated on the Cleveland
Quadrangle, a portion of which is shown in Figure 7.
Most southern Florida streams are sluggish, winding
bodies with low banks. The terrain around shell creek
is comprised of low, gently-rolling sandy sediments
attaining maximum elevations of about 20 to 25 feet
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Topographic maps


Creek in Figure 7, the stream flows into a low,
swampy flood plain as it merges with Prairie Creek
entering from the north. Any fossiliferous strata here
are likely covered by flood plain sands and
vegetation. To the east, however, especially east of
the trailer park (Figure 7), the stream is well-incised in
slightly higher terrain. Elevation rises from about 5
feet at the stream edge up to nearly twenty feet
immediately adjacent to the creek. The closely-
spaced contour lines suggest reasonably steep
banks, and as such, possible exposure of otherwise
buried subsurface strata. As it turns out, Shell Creek
does cut into shelly undifferentiated Plio-Pleistocene
units in this area, and collecting along its banks may
be carried out from a boat or canoe. In many cases,
the bottoms of streams such as this may also contain
pockets of vertebrate fossil material, derived from
sediments the stream has cut through.
The examples given above represent a small
portion of the terrain statewide. Some areas of
Florida, such as the Everglades for example, offer
little potential for the fossil collector regardless of how
many maps one studies. As shown here, however,
many other areas may be scouted for collecting sites
using the accurate land form representation provided
by the topographic quadrangle map.

A note about geology and the pitfalls
of topographic maps:
It is important to remember that the local geology
plays an important part in fossil occurrence.
Fossiliferous strata is not always present at shallow
enough depth to be intersected by surface features.
There are, for instance, many areas in Florida with
incised streams, roadcuts, canals, and karst features
which do not cut into fossiliferous sediments. This is
true for most of Florida. Successful fossil site locating
requires combining a knowledge of local stratigraphy
with the shape of the land surface. The ideal method
would entail using a geological map to locate areas
with known shallow fossiliferous strata, then
overlaying the corresponding topographic maps to
locate potential hunting sites. We can explore this
technique in a future article.

Obtaining Topographic Maps for your area:
Many public and university libraries statewide
have topographic maps available as reference
materials. Topographic quadrangles may be
purchased by mail from the U.S. Geological Survey at


the following address:

Map Distribution Section
U.S. Geological Survey
Federal Center, Box 25286
Denver, CO 80225
phone (800) 872-6277
Price is $2.50 each.

Maps for your particular area may also be
available at local sporting good stores, engineering or
survey equipment stores, some marinas, and
outdoors or trail shops. Information regarding local
(Florida) distributors of U.S. Geological Survey maps
may be obtained from the Florida Geological Survey
librarian at (904) 488-9380.
Orders for Florida quadrangles as well as
questions concerning the status of mapping, map
reference libraries, and commercial dealers may also
be directed to:

Florida Resources and Environmental
Analysis Center (FREAC)
Room 361, Bellamy Building
Attn. Jim Anderson or Peter Krafft
Florida State University
Tallahassee, FL 32306-4015
phone (904) 644-2007

Prices at FREAC are also $2.50 per map plus
$4.00 shipping for orders up to $20, $6.00 for orders
of $20-$40, or $8.00 shipping for orders in excess of
$40. Pre-payment is not necessary, and FREAC will
forward an invoice for your order.
The Index to Topographic Maps of Florida, which
shows the names and coverage areas for 7.5 minute
quadrangle maps in Florida, may be ordered free of
charge from FREAC or from the U.S. Geological
Survey.

References

Brown, R., 1988, Florida's Fossils, Guide to Location,
Identification, and Enjoyment: Sarasota, The
Pineapple Press, 208 p.

Yon, J.W., (Project Coordinator), 1972, Environmental
Geology and Hydrology, Tallahassee Area,
Florida: Florida Bureau of Geology Special
Publication 16, p. 6.