PETROLEUM POSSIBILITIES OE FLORIDA 
95 
drilled at Marathon and at Key West. Of the Marathon well a very 
complete set of samples to 1,790 feet was obtained through the courtesy 
of the Florida East Coast Railway Company. The well at Key West 
is also represented by a partial set of samples. 
Record of the well of the Florida East Coast Railway Company drilled at Mara¬ 
thon, on the Florida Keys, in 1918. This well was begun February, 1917, and com¬ 
pleted to a total depth of 2,555 feet early in 1918.'* 
Depth in feet . 
Coralline limestone, very hard. Represented by nineteen samples. 
All hard limestone, mostly finely powdered by the drill...... 35- 179 
Two samples. Very fine white sand, containing well-rounded, small 
grains of the mineral ilmenite...... 108- 274 
Four samples. Sand, medium coarse, slightly greenish in color, includes 
small amounts of clay...I..'... 305- 409 
Very coarse sand, including some phosphate pebble. Two samples.. 412- 425 
Two samples. Coarse, siliceous pebbles, including much pebble phosphate 427- 428 
Four samples. Medium coarse sand, greenish in color... 429- 471 
Two samples. Coarse sand, including clay balls..... 427- 480 
Medium coarse sand, mostly greenish in color, contains some clay frag¬ 
ments and some phosphate pebble. Seven samples... 571- 584 
Coarse sand with phosphate pebble. Three samples... 584- 589 
Porous white limestone, fossils preserved as casts. 593 
Coarse sand, including phosphate pebble. The material of this sample 
probably fell from above as the 10-inch casing had not yet been set... 598 
Limestones. Numerous samples ..... 601-1790 
This well starts in Key Largo limestone, which is Pleistocene. Accord¬ 
ing to Cushman Miocene is recognized from 180 to 412 or possibly to 
585 feet; Oligocene from 589 to 984 feet or deeper, while Lower Cre¬ 
taceous fossils are present from and below 1,248 feet. 
DISCUSSION BY COUNTIES 
ALACHUA COUNTY 
Alachua County is in central peninsular Florida. The surface mate¬ 
rials are in part those of the Alachua formation (Pliocene), the Alum 
Bluff formation (Miocene), and in part the Ocala formation (Eocene). 
Numerous water wells in this county have been drilled to a depth of 
from 150 to 472 feet, terminating in water-bearing limestones. 
*Fla. Geol. Surv., 12th Ann. Rept., p. 95, 1919. The total depth of this well is 
2,555 feet. Information by letter from the contractor, E. A. Durst, Jacksonville, 
Fla., under date of November 19, 1919. 
