PEBBLE PHOSPHATE DEPOSITS. 
33 
STRATIGRAPHIC SUCCESSION. 
EOCENE. 
OCALA FORMATION. 
Of the formations mentioned the Ocala is the earliest or oldest, 
being probably of Eocene age.* This formation consists largely of 
very pure and for the most part light colored limestones which have 
been fully described in the earlier reports of the State Survey. 
These limestones lie at or near the surface over a large area in west 
central Florida, the hard rock phosphate resting upon them, as ex¬ 
plained in the writer’s paper relating to those deposits. To the 
south, north and east of the hard rock phosphate area and probably 
to the west also the Ocala passes beneath the surface. In Sumter 
County limestones of the Ocala formation are seen as far south as 
Panasoffkee and as far east as Wildwood. In Hernando County 
these limestones are seen somewhat south of Croom. The south¬ 
ward dip of the formation is further indicated by the fact that at 
Tiger Bay in Polk County the Ocala is first encountered at a depth 
of at least 360 feet. That the formation dips to the east has been 
shown by numerous well records. 
OLIGOCENE. 
THE TAMPA FORMATION. 
The Tampa formation which consists chiefly of impure clayey 
limestones together with notable flint beds, is well exposed along 
the Hillsboro River at and above Tampa and on Hillsboro Bay. 
The silicified beds of this formation exposed at Ballast Point and 
elsewhere on Tampa Bay have received the name of the Tampa 
Silex beds, while the limestone and marls of the formation in the 
vicinity of Tampa are known as the Tampa limestone. In general 
the Tampa limestone may be expected to dip in passing to the south 
and east. This is doubtless true although the formation is with dif- 
*Unpublished manuscript of C. W. Cooke and R. S. Bassler. As early as 
1888 Mr. Joseph Willcox obtained Zeuglodont remains from the Ocala limestone 
at Ocala. A second specimen of a Zeuglodont was obtained at Ocala in 1913 
by C. W. Cooke of the U. S. Geological Survey and Herman Gunter of the 
Florida Geological Survey. In 1914 the writer obtained through Mr. Franz 
Weston from pit No. 12 of the Cummer Lumber Company near Newberry some 
whale vertebrae which have been determined bv J. W. Gidley as Basilosaurus 
brachyspondylus. Mr. Gidley adds that the specimen should be of Eocene age 
(Letter of Nov. 11, 1914). 
2-A 
