48 
FLORIDA STATE GEOLOGICAL SURVEY. 
passes through Lakeland. The theories advanced by Dali and John¬ 
son differ in one important point. Dali believes that the central 
lake basin is a synclinal valley; Johnson holds that this region which 
he designates as “high hammocks’’ or “lake region” represents the 
eroded apex of a broad arch. 
Considering the State of Florida as a whole, it is 'merely the south¬ 
ern extension of the coastal plain, and its history has in general been 
the same. Broadly speaking there are two distinct axes of uplift 
which appear to extend in a general north-south direction. The out¬ 
line of the Vicksburgian limestone west of the Apalachicola River indi¬ 
cates a gentle uplift, and field observations show that this limestone 
has there an altitude of about 75 to 100 feet over a considerable area. 
From this uplift, the rock dips rapidly to the south and west, and 
more gently, but still perceptibly, towards the southeast. Towards the 
north and northeast it rises to form the basis of the highlands of south¬ 
ern Georgia and Alabama, and then gives place to the underlying 
Jackson, which outcrops farther north. The exact trend of the uplift 
which brought the Vicksburg to its present altitude in west Florida is 
not known, but it is probably to the east of north. The peninsular 
portion of Florida represents a broad uplift such as was postulated by 
Johnson and Shaler, and the comparison with the Cincinnati arch ap¬ 
pears to be quite appropriate. The objection to the use of the term 
“anticline" in connection with these broad uplifts is due to the fact 
that most geologists are inclined to associate the word with narrower 
archings of the strata, such as are common in the Appalachian or other 
closely folded regions. By the use of the term “arch" it is hoped 
that this objection will be removed. In the peninsula of Florida, the 
arching of the beds has raised the lower Oligocene to an altitude of 
more than 100 feet above tide over considerable areas from the vi¬ 
cinity of Brooksville and Croom northward to and beyond Gainesville, 
Live Oak and Lake City. Around the outcrops of the rocks belonging 
to the Vicksburg group which have been exposed on account of the 
erosion of this arch, are the exposures of the formations which com¬ 
prise the Apalachicola group and younger beds. The rocks belonging 
to the Apalachicola group occupy a broad belt from Sarasota north¬ 
ward to the Georgia-Florida line, and extend westward to where they 
are overlapped by the beds of Miocene age. On the eastern side of 
the central uplift the Apalachicola group occupies a much narrower 
area and is soon buried beneath younger beds. Since there is little 
difference in the thickness of the beds belonging to this group on the 
east and west sides of the arch, it may be readily inferred that the 
easterly dips are more steep than the westerly. 
The northern end of the arch which forms the peninsula pitches 
gently downward, so that the limestones of the Vicksburg group dip 
