8. WEST FLORIDA COAST STRIP. 243 



there is said to be little difference between soil and subsoil in either 

 case. 



Mechanical Analyses of Soils of the Coast Strip, Escambia County. 



"Galveston sand" "Sandhill" 



Fine gravel (2-1 mm.) 0.0 o.i 



Coarse sand (1-.5 mm.) 15.5 14.2 



Medium sand (.5 — .25 mm.) 56.1 45.1 



Fine sand (.25— .1 mm.) 28.3 35.2 



Very fine sand (-i-.os mm.) . o.i 0.4 



Silt (.05-.005 mm.) 0.0 2.9 



Clay (.005-0 mm.) . — 0.0 1.9 



Total loo.o 99.9 



Both soils have remarkably low percentages of very fine sand, 

 silt and clay, which is doubtless correlated with their lack of fertil- 

 ity. The localities are not given, but the "Sandhill" sample may 

 have been taken far enough back from the coast to be influenced by 

 ants and other subterranean animals. 



The vegetation of beaches and drifting sands, though sparse, 

 consists mostly of grasses and other plants belonging to families sup- 

 posed to prefer soils well supplied with lime or potash, or both ; while 

 on the ancient dunes a little farther back, which perhaps have not 

 moved noticeably in hundreds of years, the vegetation is quite dif- 

 ferent, consisting mostly of pines and evergreen shrubs, with prac- 

 tically no grasses, indicating an extremely sterile soil. It seems very 

 probable that the lime and potash (derived from shells, seaweeds, 

 etc.) that were in the latter soil when it was first thrown up by 

 waves and wind have long ago been almost entirely leached out by 

 the copious summer rains. 



Salamanders, which have no known way of crossing water, 

 seem to be entirely absent from the islands, and thus one important 

 agent that helps maintain the fertility of some Florida soils is lack- 

 ing. None have been observed on the old dunes of the mainland 

 either, though the reason for their absence there is less obvious. 

 Gophers and ants inhabit the soil of the oldest dunes near Lanark 

 (and probably elsewhere), and the vegetation there is very similar 

 to that on sandy ridges farther inland, indicating a better soil than 

 that of the stationary dunes on the outer islands. 



Topography and Hydrography — The topographic forms are 

 those common to many sandy coasts ; namely, beaches, dunes, 

 marshes, etc. The dunes are not as extensively developed as on the 



