256 FLORIDA GEOLOGICAL SURVEY-SEVENTH ANNUAL REPORT. 
east of the east county line, swinging around a few miles north of the 
north county line. The range in elevation within the county is about 
140 feet, or from about 60 to approximately 200 feet above tide. 
The drainage is toward the south and west. The county is drained 
by the Santa Fe River and its tributaries, including mainly Alli¬ 
gator Creek, Sampson River, New River, and Olustee Creek, with 
their numerous branches. All of these streams flow in either a 
southern, western, or southwestern direction. 
Some sections of the county have well-defined drainage systems. 
Much of the flat country, however, is inundated during seasons of 
heavy rainfall, and cypress ponds, bays, and swamps remain filled 
with water for long periods. 
The northern and eastern parts of the county lie almost entirely 
within the flatwoods region. The topography of this section is 
flat to gently undulating, with but a few slight surface variations. 
As the larger streams are approached the surface becomes gradually 
more undulating and in places even rolling to hilloeky, with rel¬ 
atively deep, narrow, well-defined valleys. The highest elevations 
are in the northeastern part of the county. The country along the 
larger streams, notably the Santa Fe River, the New River, Olustee 
Creek, and Swifts Creek near its confluence with Olustee, has a 
more rolling topography, including ridges which in places terminate 
with a bluff along the streams. In this section the valleys are nar¬ 
row, and the numerous smaller streams or ‘‘branches” which work 
back into the uplands from the larger streams give the country a 
decidedly billowy surface. 
Farther back from the larger streams, beyond the heads of the 
tributary streams, the country has a more nearly level topography, 
difference in elevation between the stream courses and the crests of 
the divides being barely perceptible. As this country is approached 
the floors of the stream valleys rise gently until they approach the 
general level of the upland, their power of erosion lessening until 
they become almost negligible in altering the level topography. The 
stream valleys are therefore shallow, and it is difficult in many cases 
to determine the extent of the overflow land, owing* to the gradual 
merging of the bottoms into the upland. In some cases the pre¬ 
vailing surface has so slight an elevation above that of the stream 
courses that the water spreads out from the stream channels in 
places over large expanses of the surrounding country, forming 
“swamps” which support a luxuriant growth of subtropical water- 
