44 FLORIDA GEOLOGICAL SURVEY SIXTH ANNUAL REPORT. 



limestone seerrn -also to have been brought up from the lake at the 

 entrance of the north New River canal. 



The following analysis of a composite sample of the hard and 

 soft phases of this limestone, as well as the other analyses given 

 in this paper, was made by the State Chemist from samples taken 

 for the purpose by the writer. The rock in Lake Okeechobee, as 

 is seen from this analysis, is slightly phosphatic, this being the 

 only phosphatic limestone as yet reported from the Everglades. 



Analysis of Limestone from Lake Okeechobee. 



Per cent 



Calcium Oxide, 42.76%, equivalent to Calcium Carbonate 76-37 



Magnesium Oxide, 0.35%, equivalent to Magnesium Carbonate 0.70 



Phosphoric Acid, 0.85%, equivalent to Tricalcium Phosphate 1.85 



Insoluble matter, silica, etc 21.14 



From the canals leading out of Lake Okeechobee to the south 

 and southeast for a distance of about 25 miles very little rock has 

 as yet been removed. Such fragments as are seen along the canals, 

 however, represent very hard compact fresh-water limestones. On 

 the North New River canal dredging of the heavy limestone begins 

 about 26 miles from Lake Okeechobee. The rock cut through on 

 this part of the canal consists of a very hard, compact, close- 

 grained limestone which breaks with a sharp fracture and will 

 evidently make valuable concrete material. The same limestone 

 is cut into on the South Canal at 24 miles from the lake. The very 

 hard phase of this rock is a fresh-water liijiestone. As found on ' 

 the banks of the canal, however, marine and fresh-water limestones 

 and marls are intermixed, indicating that here as elsewhere the 

 formation includes alternating fresh-water and marine deposits. 

 While the shallow-water shell, Chione cancellata, occurs here as at 

 Coffee Mill Hammock, the predominating fossil in the Everglades 

 is the estuarine and shallow-water form, Rangia cuneata, together 

 with corals and other forms that inhabit shallow marine water. 

 Pieces of this hard limestone are found on the North New River 

 canal as far as 42 miles from the Lake, although for the last three or 

 four miles of this distance the heavy limestone stratum gives 

 place largely to marls. 



The following is an analysis of a sample of this rock from the 

 South New River canal, 25 miles south of Lake Okeechobee. 



