122 
FLORIDA STATE GEOLOGICAL SURVEY. 
The maximum elevation for Eastern Florida is found in the north¬ 
western part of Clay County, approaching “Trail Ridge.” On 
this ridge are found, according to levels made in 1911 by the 
United States Geological Survey, a maximum elevation of 246 
feet. In Polk County elevations approximating 250 feet are also 
reported. (See map.) 
RIVERS. 
The St. Johns River rises from the lakes of southern Brevard 
County, within a few miles of the Atlantic coast. From this point 
it flows north or slightly west of north about 200 miles, entering 
the Atlantic Ocean within 25 miles of the north line of the State. 
The elevations along this river at no point exceed 25 feet above 
sea, the entire valley lying within the artesian flow area of the 
State. The principal tributaries of the St. Johns are Black Creek 
and Ocklawaha River. The former heads in the uplands of Clay 
County, while the latter is fed from numerous lakes of Lake 
County and receives tributaries from Silver Springs in Marion 
County and from the lakes of southeastern Alachua County. 
The St. Mary’s River, forming a part of the northern boun¬ 
dary of the State, rises in or near Okefenokee Swamp, in Georgia. 
From its origin it flows south until on a parallel with the mouth 
of the St. Johns river. From this point it bends abruptly and 
flows north for thirty miles, then, turning again, flows a little 
south of east to the Atlantic Ocean. Nassau is one of the smaller 
rivers and with its tributary, Thomas Creek, forms part of the 
boundary between Nassau and Duval Counties. The Withlacoo- 
chee, Hillsboro, Peace and Caloosahatchee rivers flow into the 
Gulf. 
Bordering the streams, both the main rivers and their tribu¬ 
taries, are found in many places, open, flat, imperfectly drained 
pine lands. These lands are classed in the section treating of soils 
as open flatwoods. A somewhat different and more extensive 
type of country is that designated as palmetto flatwoods. An 
essential difference in these two types of country is the presence 
or absence of the saw palmetto, the pine forest being common to 
both. In Nassau and Duval Counties and along the tributaries 
