188 PROCEEDINGS OP THE ACADEMY OP [1884. 



NOTES ON THE GEOLOGY AND NATUKAL HISTORY OF THE WEST COAST 



OF FLORIDA. 



BY JOSEPH WILLCOX. 



The following notes apply especially to the Counties of Levy 

 and Hernando in Florida. That portion of the Peninsula consists 

 of a fine grained limestone composed largely of foraminifera, 

 several species of which have been determined by Prof. Heilprin. 

 The limestone is covered with sand, in some places with a thin 

 layer only, while, at other localities, wells sunk to the depth of 

 25 or 30 feet have failed to indicate the presence of rocks. In 

 many places the rocks are exposed above the surface of the 

 ground. They are hard and compact when dry ; but, when they 

 are permanently wet, they are comparatively soft, and are eroded 

 with facility. In fact, throughout a large portion of the State 

 numerous and long subterranean caverns abound, that serve as 

 aqueducts to convey the water supplying the many large springs, 

 for which this territory is noted. 



The subsidence of the surface ground into these caverns has 

 caused many sink-holes. Three miles south of Gainesville, within 

 a space of less than 100 acres, nearly fifty funnel-shaped sink- 

 holes exist, from 20 to 200 feet in diameter at the top, and from 

 10 to 50 feet deep. 



These are near to Payne's Prairie, a lake covering a space of 

 about forty square miles. This lake has no outlet, and its surface 

 rises and falls, as is usual in such cases, according to the 

 abundance or scarcity of rain. 



It covers an area that was dry land a few years ago. The 

 creek, which now supplies water to it, formerly flowed into a sink 

 hole near those mentioned above. This creek undoubtedly was 

 the active agent in eroding the caverns into which the material 

 formerly occupying the space where the sink-holes now exist 

 was precipitated. Some sink-holes are large and the subsidence 

 moderate. Examples of the latter case may be seen in numerous 

 shallow ponds and cypress swamps. Many large lakes probably 

 owe their existence to the same cause. 



The limestone is, in some localities, replaced by a chert rock, 

 in which the casts of shells are still visible. This rock forms the 



