68 FLORIDA GEOLOGICAL SURVEY-TWELFTH ANNUAL REPORT 
over 700 square miles which heretofore has been concealed by the 
waters of this lake.* 
The geologic section which is here described extends from the 
Gulf of Mexico to the Atlantic Ocean. The line of the section 
follows the Caloosahatchee River to Fort Thompson, 50 miles - ; 
thence through the canals and small lakes in a general, easterly 
cliiection to Lake Okeechobee about 25 miles. From Lake Okee¬ 
chobee the section follows the North New River Canal in a south 
easterly direction to New River, 57 miles; thence to the Atlantic 
Ocean about 8* miles; or a total distance from the Gulf to the At¬ 
lantic of 135 miles. The oldest formations found in this section 
lie at the west or Gulf side, while the newer formations lie on the 
east, and hence as a matter of convenience the section will be de¬ 
scribed from west to east. Large collections of fossils, as well as 
lithologic samples of the formations were made which are avail¬ 
able for subsequent study. In making the examination of the ex¬ 
posures along the canals and in Lake Okeechobee a small launch 
was used, placed at the writer’s disposal for that purpose through 
the courtesy of the State Drainage Commission. 
THE SUB-STRUCTURE OF THE EVERGLADES. 
The Eocene limestones which are extensively exposed north 
and west of the Everglades underlie that area although they are 
not seen at the surface. At Fort Meade, about 100 miles north¬ 
west of Lake Okeechobee, limestones as shown by well drillings, 
lie at a depth of 410 feet front the surface while on the Atlantic 
Coast, similar limestones as shown by well records at Palm Beach 
lie not less than 900 feet from the surface, indicating, a general 
eastward dip, although possibly with local variations. At Key 
West about 100 miles southwest of the southern border of the 
Everglades, this limestone lies at a depth of about 700 feet from 
*The area of Lake Okeechobee at stage of water 20 feet above sea, is 730 
square miles, at 16 feet, 710 square miles. Report of Florida Everglades Com¬ 
mission, p. 10, 1913, Senate Document No. 379. With the exception of Lake 
Michigan it is thus the largest fresh water lake lying wholly within the United 
States. 
