COMPOSITION OF THE EUTAW FOllMvVTION. 591 



Section of Eutaw Rocks; Chattahoochee River. 



Base of liipley group. 



Feet. 



1 — Light-yellow and white sands, containing beds of well-rounded quartzose peb- 

 bles ; beds sometimes 20 feet thick. Lignitized logs can be seen protruding 

 from the bluffs. The sands contain, at rare intervals, shells of a small 

 Exogyra, probably the young of E. densata. Say 45 



2 — Yellow sands and gray clay, cross-bedded and containing bits of leaves. This 



bed and the preceding are seen at Chimney bluff, Georgia 60 



3 — Quartzose conglomerate much like that at Havana, Hale county, Alabama;^ 

 forms the shoal at Beden's rock and the bluff at Hatcher's lower landing ; 

 merges gradually into a yellow sand 50 



4 — Yellow and white sands, with seams of lignitic sand and an occasional 

 "bunch" of gray laminated clay. This stratum is exposed in a bluff about 

 100 yards from the river, just south of Rooney's Mill creek, Georgia 50 



5 — Laminated dark-gray clays, with masses of yellow sands distributed at irregu- 

 lar intervals throughout the stratum ; best developed just above Uchee 

 creek, Alabama 25 



6 — Gray, calcareous, laminated sandy clay, containing calcite plates and some 

 fossils in the lower part. The upper part of this stratum becomes more 

 argillaceous and contains many fossil casts, mainl}^ lamellibranchs ; causes 

 landslides like the Black Bluff clays (Eocene), which it resembles some- 

 what physically. These sandy clays give rise to the Uchee shoals 100 



7 — Dark-gray calcareous sand, pyritous and containing nodular masses 6 to 12 

 inches in diameter, with calcite nuclei. These nodules are arranged in strata 

 about 12 inches thick. Fragments of lignite are scattered through this 

 stratum, some of them filled with calcified teredos. The only other fossils 

 seen are Eogyra densata, Say (young), and an Ano?nia, all poorly preserved ; 

 dip at this point, 40 feet to the mile southward 15 



Tuscaloosa group. 



The Rotten Limestone. — East of the drainage of the Alabama river the 

 Eotten limestone, such as occurs in Marengo, Perry, Dallas, Lowndes, and 

 Montgomery counties (Alabama), is not represented. The exact eastern 

 limit of this group has not as yet been determined, but evidences of its de- 

 creasing thickness are seen in the narrow outcrop in the neighborhood of 

 Pike road, Montgomery county, where its north-and-south extent is only five 

 miles, as compared with thirty miles in Dallas county. Further than this 

 decrease in thickness, present information does not warrant saying anything. 

 As has been stated before, no rocks bearing any lithological resemblance to 

 the Rotten limestone have been seen overlying the Eutaw group on the 

 Chattahoochee river. Whether or not this group is represented by strata of 

 different composition from the typical aluminous limestone it is difficult to 



*Ibid., p. 111. 



