OCKLOCKNEE AND AUCILLA RIVERS. 
139 
The progressive changes in the basins and in the drainage sys¬ 
tems that have been described indicate progressive physiographic 
development. From the Gulf inland the land surface is being grad¬ 
ually lowered to base level. This process is more rapid where lime¬ 
stones lie near the surface than where there is no limestone or where 
the limestone lies deeply buried beneath other formations. Near 
the Gulf Coast the limestone country of this area has been reduced 
practically to base level and the streams have become surface 
streams flowing in the limestone. Farther inland base level has 
been reached only in limited areas in which have been developed the 
large basins, several of which have been described. The large area 
that has been base leveled probably was reduced in elevation through 
the same processes that are now active farther inland. The con¬ 
tinuation of these processes in the future must result in the gradual 
lowering of the land surface in the present lake region of Leon and 
Jefferson counties until the whole area becomes a plane at base level 
when the location of the present basins will have become obscure 
and the basins as such obliterated, as others probably have formed 
and disappeared in the at present level areas nearer the coast. 
At page 100 of this report is inserted a map showing contour 
lines and indicating the location of basins and plateaus. From 
this map may be seen the progress of topographic and physio¬ 
graphic development. The land in the south-eastern part of this 
area has been reduced to an approximately uniform level, while to 
the south-west where the limestones pass below the surface the 
land has been but little affected by erosion. In the northern part 
of the area is found a maximum of topographic diversity for this 
area, the basins having been carried essentially to base level, while 
in places the plateau still retains its original height. 
