594 D. W. LANGDON, JR. — CRETACEOUS AND TERTIARY STRATA. 



Feet. 



20 — Cross-bedded gray sands and cla}'^ 15 



21 — Sandy stratum, indurated and containing Ostraia^ sp. (?) 1 



22 — Gray, highly fossiliferous marl. The fossils are near]}'-, if not quite, all bi- 

 valves, and are mostly comminuted as if they formed an ancient shore- 

 line. There are numerous shark and sauroid teeth, mammalian bones, a 

 hard black substance in sections resembling the under shell of a turtle, 



black coprolitic pebbles, and fragments of lignite 3 



23 — Gray and yellow sands resembling physically those of the Tertiary at Lower 



Peach Tree, Alabama* [ 30 



24 — Gray sand interhiminated with thin seams of more argillaceous sand, all of 



which is unfossiliferous 26 



25 — Gray sandy calcareous clay, with lines of bowlder-like concretions projecting 

 from the bank ; first seen at Lawson's wood-yard, Georgia. Few fossils 

 except E. costata, Say, occur in the lower part of this stratum. A mile 

 above Blufftown, Georgia, characteristic Kipley shells, mainly bivalves, 

 are foutid in a much decomposed state throughout a stratum 6 to 8 feet 

 thick, while the uppermost 10 feet of the entire stratum is very fossiliferous. 

 Near Jernigan's Landing, Alabama, slight rolls in the strata are seen, in- 

 volving about 20 feet of the sands. These miniature anticlinals and syn- 

 clinals continue to v/ithin two miles of Florence, Georgia 120 



Eutaw group. 



Tertiary Strata. 



Thickness and Divisions. — Hilgard f appears to be somewhat in doubt as 

 to the exact thickness and characteristics of the Tertiary in Mississippi, 

 placing it at about 620 feet, exclusive of the Grand Gulf, which is probably 

 post-Eocene. 



Smith J divides the Eocene into three parts: the lower, consisting of the 

 Midway, Black Bluff, Matthews' Landing or Naheola, Nanafalia, Bell's 

 Landing or Tuscahoma, Wood's Bluff or Bashi, and Hatchetigbee ; the mid- 

 dle, comprising the Buhrstone and Claiborne ; and the upper, which includes 

 the Jackson and Vicksburg; in aggregate thickness reaching about 1,700 

 feet. In the Chattahoochee water-shed the total thickness is not more than 

 1,200 feet, and many groups represented along the western border of the 

 state are entirely lacking, while others are so attenuated as to have almost 

 lost their identity. 



The Midway or Clayton. — At the typical locality on the Alabama river, the 

 Midway group consists of 10 feet of light gray, very argillaceous limestone, 

 characterized by Nautilus (^Enclimatoeeras) iilrichi, Hyatt. Following the 

 group eastward for 20 miles to the vicinity of Allenton, Alabama, this lime- 

 stone has lost its argillaceous character, and is underlain by an additional 15 



* Ibid., p. 48. 



t Agrie. and Geol. of Miss., 1800, pp. 107-110. 



t Bull. 43 U. S. Geol. Survey, 188(1, p. 18. 



