THE ARTESIAN WATER SUPPLY OF EASTERN FLORIDA. 
93 
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. 
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. The palmetto flatwoods is the prevailing type of country 
throughout the southern part of this area. In Nassau and Duval 
Counties and along the tributaries of the St. Johns River extensive 
areas of open flatwoods occur. 
Along the border of the uplands back from 1 the river and from 
the coast a different type of topography has developed, consisting 
largely of the sandy or rolling pine type of soil although scrub 
hammock lands occur. These several types of country are due 
to a considerable extent to the drainage conditions. On the sum¬ 
mit of the plateau in the interior of Florida, palmetto flatwoods 
and to some extent open flatwoods are again encountered. 
THE LAKE REGION, 
The lake region is a term that has come to be applied in Florida 
to a characteristic type of topography. The term does not refer 
merely to a section in which lakes occur, but is restricted in usage 
to apply to a section in which a particular type of lakes occur. The 
lake region consists of irregularly placed hills which descend 
abruptly to circular lakes. The soil is prevailingly sandy and well 
drained. There are few if any surface streams, and the lakes have, 
as a rule, no surface outlet. 
The lake region type of topography occurs in those parts of the 
State in which soluble limestones, although buried to a considerable 
depth beneath other formations, nevertheless lie sufficiently near the 
surface to affect the topography. In that part of the State in which 
limestones lie at or very near the surface large lakes rarely occur, 
although sink holes are frequent, some of which may contain water 
forming small sink hole lakes. On the other hand where the soluble 
limestones are so completely buried beneath other formations as 
to have no effect on the topography lakes of this type do not 
occur. 
