SECOND ANNUAL REPORT—STRATIGRAPHIC GEOLOGY. 
61 
Thickness:—No definite determination of the maximum thickness 
of the Ocala limestone has been made, and as yet no exposures have 
been observed which show the contact with the underlying “Peninsu¬ 
lar” limestone. All the information now available indicates that the 
thickness may be variable, and that the variation is in considerable 
measure due to subsequent erosion rather than inequalities of depo¬ 
sition. In the Transactions of the Wagner Free Institute of Science, 
Dr. Dali 1 states that at the type locality the Ocala limestone has been 
quarried to a depth of twenty feet without reaching its contact with 
the underlying “Peninsular’’ limestone. The greatest thickness noted 
during the recent field investigation was in a sink-hole near Ocala 
where the formation is exposed to a depth of about forty feet without 
reaching its base. This locality is described in a subsequent part of 
the discussion. 
Physiographic Expression:—As in the case of the “Peninsular” 
limestone, the Ocala limestone is soft and porous, and hence gives 
rise to a topography which is characterized by underground channels, 
sink-holes, sinking streams, natural bridges, and large springs. The 
limestone has an important influence in the formation of many of 
the lake basins, and it forms the natural bridge of the Santa Fe River 
near High Springs. Large springs from the Ocala limestone are 
numerous in the central part of the peninsula. 
Paleontologic Characters:—The Ocala limestone, like the under¬ 
lying “Peninsular,” is characterized by a great number of foraminif- 
era, but it differs from the latter in the presence of nummulites. A 
few mollusks are said to be restricted to this formation, but as yet 
the fauna is very imperfectly known, and future study may add to the 
number of fossils which are peculiar to it. 
Structure:—The Ocala limestone shows the same structural feat¬ 
ures as the underlying “Peninsular,” and there is little reason to doubt 
that both have been subjected to -the same movements since their 
deposition. 
Local Details:—-One of the earliest statements relating to the type 
locality of the Ocala limestone was made by Prof. LeConte in his 
description of the Silver Spring. 2 He says (p. 11) : 
As in some measure related to the peculiar system of subterranean drainage 
above indicated, it may not be deemed inappropriate to conclude this communica¬ 
tion with a few general remarks in relation to the physical causes which have 
produced the several qualities of surface soil which are found in the neighbor¬ 
hood of Ocala and the Silver Spring. The whole of this portion of the Penin- 
1 Dali, Wm. H., Trans. Wagner Free Inst. Sci., vol. iii, pt. 6, 1903, p. 1556. 
2 Le Conte, Prof. John. On the optical phenomena presented by the “Silver 
Spring” in Marion County, Florida. Am. Jour. Sci., 2nd series, vol. xxxi, 186L 
pp. 1-12. 
