28 AGRICULTURAL ANALYSIS 



of the forces which have been briefly outlined was the formation 

 of bowlders, phosphatic debris, etc. Wyatt therefore classifies 

 the deposits in Florida as follows : 



1. Original pockets or cavities in the limestone filled with hard 

 and soft rock phosphates and debris. 



2. Mounds or beaches, rolled up on the elevated points, and 

 chiefly consisting of huge bowlders of phosphate rock. 



3. Drift or disintegrated rock, covering immense areas, chiefly 

 in Polk and Hillsboro counties, and underlying Peace River and 

 its tributaries. 



Darton ascribes the phosphate beds of Florida to the trans- 

 formation of guano. 16 According to this author, two pro- 

 cesses of decomposition have taken place. One of these is 

 the more or less complete replacement of the carbonate by the 

 phosphate of lime. The other is a general stalactitic coating 

 of phosphatic material. Darton further calls attention to the 

 relation of the distribution of the phosphate deposits as affecting 

 the theory of their origin, but does not find any peculiar signifi- 

 cance in the restriction of these deposits to the western ridge of 

 the Florida peninsula. 



As this region evidently constituted a long narrow peninsula 

 during early miocene time it is a reasonably tentative hypothe- 

 sis that during this period guanos were deposited from which 

 was derived the material for the phosphatization of the limestone 

 either at the same time or soon after. 



Darton closes his paper by saying that the phosphate deposits 

 in Florida will require careful detailed geologic exploration be- 

 fore their relations and history will be fully understood. 



According to Dr. N. A. Pratt the rock or bowlder phosphate 

 had its immediate origin in animal life and to his view 

 the phosphate bowlder is a true fossil. He supposes the exist- 

 ence of some species in former times in which the shell excreted 

 was chiefly phosphate of lime. The fossil bowlder, therefore, 

 becomes the remains of a huge foraminifer which had identical 

 composition in its skeleton with true bone deposits or of organic 

 matter. 



1(1 American Journal of Science, 1891, 41 : 104. 



