72 Florida geological survey— 14 TH annual report 
the upper part of the Jackson formation of Alabama. 1 Over this area 
in Florida this formation is thin and in places possibly entirely absent. 
The Claiborne formation, or series of formations, is found extensively 
developed in Alabama, and in that state the group is divided by Smith 
into three formations as follows: The Gosport Greensand at the top, 
followed by the Lisbon formation and the Tallahatta buhrstone. 
The uppermost of these formations, the Gosport, has in Alabama a 
thickness not exceeding 30 feet, and consists of highly fossiliferous 
glauconitic sands. The Lisbon is said to include, in Alabama, about 115 
feet of calcareous sandy clays and clayey sands. The Tallahatta buhr¬ 
stone, the lowermost formation of the Claiborne, has, according to Smith, 
a thickness, in eastern Alabama, of about 200 feet. The rocks of this 
formation in Alabama are quite calcareous. 
Thus the whole thickness of the Claiborne in eastern Alabama, ac¬ 
cording to Smith, approximates 345 feet. The group of formations of 
the Claiborne as there developed include extensive beds of greensand. 
Whether the Claiborne Group will be found to thin out or to become 
thicker in Florida has not been determined. 
The Wilcox Group of formations, which lies next below the Claiborne, 
outcrops at the surface in Alabama a few miles north of the north Flor¬ 
ida boundary. The Wilcox Group has been separated in Alabama on 
the basis of the fossils, into four formations which are in order as fol¬ 
lows, beginning with the uppermost or latest of the series: Hatchetig- 
bee, Bashi, Tuscahoma, and Nanafalia. These formations, according 
to Smith, consist of cross-bedded sands, thin-bedded or laminated sands, 
laminated clays and clayey sands, with beds of lignite or lignitic matter 
sufficient to color the sands and clays. 2 
The formations are notably variable in lithology and the separate 
members probably could with difficulty be distinguished in well records. 
The entire series in Alabama has a thickness of approximately 900 feet. 
The basal Tertiary sediments, the Midway Group, include in eastern 
Alabama, according to Smith, approximately 200 feet of calcareous 
sands and limestones. 
A well located in the Marianna-Chipley region, starting in the Upper 
Eocene or Lower Oligocene, may therefore be expected to encounter 
1,500 or 2,000 feet of Tertiary sediments before entering the Cretaceous. 
1 U. S. Geol. Surv., Professional Paper 95, p. 117, 1915. 
Underground Water Resources, Ala. Geol. Surv., 1907, p. 16. 
