GEOLOGIC SECTIONS ACROSS THE EVERGLADES. 
75 
or four miles of this distance the heavy limestone stratum gives 
place largely to marls. It seems very probable that the deposits 
cut through in this part of the Everglades represents the eastward 
extent of the Fort Thompson Limestone with its associated fresh 
water and marine shell mtfarls. 
MIAMI FORMATIONS. 
Another limestone seen on the North New River Canal is cut 
into by the dredge at a distance of about 42 miles from Lake 
Okeechobee. This limestone is granular and is more or less dis¬ 
tinctly oolitic in structure and is not so hard as that seen nearer 
the lake. The surface of this rock becomes very rough on ex¬ 
posure presenting a characteristic matted appearance. This rock 
is seen in the canal to within 9 miles of Fort Lauderdale (52 miles 
from Lake Okeechobee). Until its extent and thickness are more 
definitely known, this limestone is, perhaps, best regarded as a 
member of the Miami formation, the typical representative of 
which, is the Miami oolitic limestone which is found at the surface 
in the vicinity of Miami. 
The typical Miami oolitic limestone is first seen in this canal 
about 6 miles from; Fort Lauderdale (55 miles from Lake Okee¬ 
chobee). For about 3 miles above this point no rock is found in 
the canal banks, only sand being reached by the dredge. The 
absence of rock from this part of the section indicates clearly 
that a sand stratum some feet in thickness intervenes between the 
limestone described in the last paragraph and the typical Miami 
oolite. From its first appearance in the canal the Miami oolite is 
continuous to the coast forming the country rock in this part of 
the section. 
The relation of the Fort Thompson beds to the Miami Oolitic 
limestone was not determined owing to the lack of continuous 
exposures. The succession of deposits indicates alternating fresh 
water and marine conditions, but whether these conditions pre¬ 
vailed in this area previous to the deposition of the Miami oolite 
or subsequent to that time can be determined only by more de¬ 
tailed stratigraphic and paleontologic studies than have been made 
in this area. 
