AGE OF THE UNDERLYING ROCKS OF FLORIDA 
99 
Augustine at 400 feet, Jacksonville at 820-845 feet, Tiger Bay at 
500 feet and Marathon 1,248 feet below present sea level. Allow¬ 
ing for an even rate, this would give a dip to the south from 
Apopka to Tiger Bay of approximately 9 feet to the mile. Simi¬ 
larly the dip northward from Apopka to St. Augustine about 6 
feet per mile and from Anthony northeastward to St. Augustine 
also about 6 feet per mile. From St. Augustine to Jacksonville 
the dip is sharper if the data are correct and nearly 10 feet per 
mile. All these represent fairly uniform conditions and very grad¬ 
ual slopes in a low anticline with its center somewhere in the gen¬ 
eral region of Apopka. Owing to the absence of samples from the 
upper portion of the Bushnell well and the lack of deep samples 
from Sanford and Cocoa, the east and west dip of the Lower Cre¬ 
taceous cannot be determined. 
The time of the slight folding into the anticline is an interest¬ 
ing problem. The fact that the horizon of the conical Orbitolina 
is approximately the same as or parallel to the upper surface of 
the Lower Cretaceous would tend to show that unequal erosion 
which would have taken place if it occurred soon after deposition 
has not taken place to any great extent. The evidence furnished 
by later formations tends to support this view. 
In this connection the following statement of Vaughan (Dept. 
Marine Biology, Carnegie Institution of Washington, Papers from 
the Tortugas Laboratory, Vol. 4, p. 181, 1910) in speaking of the 
origins of the Floridian Plateau seems to have been very close to 
the actual facts. 
“The Plateau existed in Vicksburgian, Lower Oligocene, time 
[the Ocala now considered as Upper Eocene] projecting as a sub¬ 
marine platform from the southeastern corner of the continental 
shelf and extending at least to its present southern limit. The 
forces by which this older Oligocene [Upper Eocene] platform 
was formed at present can only be the subject of speculation. It 
was due to some fold of the ocean bottom, perhaps in some way 
connected with the angle of the Piedmont area in central Georgia.” 
UPPER CRETACEOUS. 
It seems safe to make the statement that so far as the well sam¬ 
ples examined show, there are no Upper Cretaceous strata now 
