

364 BOTAXICAL GAZETTE [may 



deposits of the coast- For most of its course along the western 

 border of Leon County its banks are edged by bluffs of varying 

 elevation (50-100 ft. above sea-level). These are apparently the 

 ancient banks, eroded during a previous period. At places these 

 bluffs approach close to the present low banks, so that the valley 

 varies in width. The erosion work of the river is of small impor- 

 tance, and in its bordering meadow and overflow land it resembles 

 a pre-erosion stream. The low bluffs are generally well wooded 

 and the undergrwoth is often denser and of a more mesophytic 

 type than is that of the upland forest. 



Examples of small erosion creeks are to be seen in the south- 

 western edge of the county, where a series of drainage streams flow 

 from the bays on the Leon sand across the strip of Norfolk sand to 

 empty into the Ocklocknee River, and have cut ravine-like valleys 

 in the sands, in which the most mesophytic trees, including Magnolia 

 grandi flora L., Fagus grandifolia caroliniana Fernald and Rehder. 

 Liriodendron Tulipifera L., Carya alba K. Koch, Acer spp., Carpinus 

 caroliniana Walt., and Prunus caroliniana Mill., grow with a rich 

 undergrowth. Entering one of these eroded valleys from the 

 upland of monotonous pine forests, one witnesses the extremes 

 which the region can support. 



Lakes. — The surface erosion along the shores of the larger lakes 

 is of small importance, as the shores are usually sloping and the 

 wave action is slight. The trees of the uplands may extend to the 

 water's edge or there may be tracts of fine hammock forest. Other 

 lakes resemble slow fluctuating streams, with cypresses in the 

 shallow water. 



Subterranean erosion 



The underground solution and the resultant caving in or settling 

 of the ground surface continue to play a part in modifying the 

 topography. 



Sinkholes. — The formation of sinkholes may take place sud- 

 denly and expose the limestone, forming depressions, usually cir- 

 cular, varying in size and depth. In case there is no opening 

 through which the water may reach an underground channel, the 

 rainfall and the surface waters mav accumulate to form a pond- 





