Sellards — Comanchean Formation. 13 



Akt. II. — Comanchean Formations underlying Florida; 

 by E. H. Sellaeds. 



During the latter part of 1917 the Florida Geological 

 Survey received through the courtesy of Mr. H. B. Good- 

 rich, a very important set of well samples from a deep 

 well then recently completed by the Dundee Petroleum 

 Company in Sumter County, Florida. Early in 1918 a 

 few of the samples from this well, in which f oraminifera 

 were abundant, were forwarded by the writer to Dr. T. W. 

 Yaughan of the United States Geological Survey by 

 whom they were referred to Dr. Joseph A. Cushman. 

 The foraminifera of these samples indicated, according 

 to Dr. Cushman, the presence of Comanchean formations 

 in this well. Subsequently Dr. Cushman undertook for 

 the State Survey a study of the cuttings from some fif- 

 teen wells in Florida, and has now published the results 

 of his study. 1 The location of the wells from which 

 samples were obtained is indicated on the accompanying 

 sketch map (fig. 1). 



In nine of the wells Comanchean fossils were recog- 

 nized. These are numbers 2, 3, 4, 5, 7, 8, 11, and 15 as 

 shown on the map. Numbers 6, 9, and 10, in which 

 Comanchean fossils were not found, are shallow wells, 

 from 113 to 190 feet in depth, terminating in the Eocene 

 formations. Well number 12, at the north side of Lake 

 Okeechobee, was represented by samples to the depth of 

 only 500 feet ; number 13, at Boca Grande, is represented 

 by but one sample in which no characteristic fossils were 

 found ; number 14, at Ft. Myers, from which no Coman- 

 chean fossils were obtained, is represented by a series of 

 samples submitted by the driller as representing the for- 

 mations to the depth of 950 feet. Examining the results 

 as a whole it is seen that fossils of the Comanchean for- 

 mations were recognized in all wells of considerable depth 

 from near Tallahassee in West Florida to Cocoa and 

 Tiger Bay somewhat south of the center of peninsular 

 Florida. In southern Florida these formations, although 

 present as indicated by the well on the Florida Keys (well 

 No. 15), lie at a much greater depth than in Central 

 Florida. 



Owing to the relatively small number of samples 



x Fla. Geol. Survey, 12th Ann. Kpt., 1919. 



