122 Florida geological survey—14TH annual report 
The Alum Bluff formation dips under the county from the northeast 
and all surface formations, with the possible exception of those in the 
northeast portion, may safely be regarded as later than Lower Miocene. 
Near the coast the surface formations doubtless are Pleistocene. Plio¬ 
cene and Upper Miocene sediments may be present in the central part 
of the county, although their presence has not been demonstrated. 
No deep wells have been drilled in this county. 
SARASOTA COUNTY 
Sarasota County lies adjacent to the Gulf coast, in the southern part 
of Florida. The Alum Bluff formation is occasionally exposed on the 
coast and in stream beds in this county. Elsewhere it is overlaid by a 
thin veneer of later sediments, chiefly derived from the Alum Bluff. 
No wells of unusual depth are recorded, although artesian water is 
obtained at depths ranging from 52 to 455 feet. 
SEMINOLE COUNTY 
With the exception of recent shell mounds on the St. Johns River, no 
deposits containing fossils by which the age of the formations may be 
determined have been found in Seminole County. It is known, how¬ 
ever, from well drillings, that at Sanford the Eocene limestones are 
reached at the shallow depth of about 113 feet. The presence of the 
Eocene so near the surface at this place indicates a very mild dip to the 
east from the Eocene exposures of central Florida. No logs of the deep 
wells that have been drilled in this county are available. Shallow arte¬ 
sian wells are very numerous. 
Following is a log of one of these shallow wells :* 
Depth in feet. 
Surface soil ................. 0- 5 
Yellow sand .. 5- 40 
Shell and sand, water, no flow... 40- 60 
Sand ........ 60- 91 
Shell and sand, with sharks’ teeth.......... 91- 95 
Dark blue rock, with black phosphatic pebbles...... 95-100 • 
Very dark rock ....... 100-101 
Light yellow sand ....... 101-113 
Limestone, Eocene .... 113 
*Fla. Geol. Surv., 5th Ann. Rept., p. 219, 1913. 
