/4 J. J. STEYEXSON — LOWER CARBONIFEROrS, APPALACHIAN BASIN 



absent throughout, being represented by the Oxmoor sandstone, which 

 includes the Floyd shale of Hayes. This contains irregular beds of 

 nodular limestone, occasionally some chert, and usually has at the bottom 

 one or two beds of massive sandstone, one of which sometimes becomes 

 conglomerate at the extreme southeast exposures in Talledega and 

 Shelby ; but for the most part it is made up of black shale. The thick- 

 ness is from 1,000 to 1,500 feet, being greatest at the southeast.^ 



The next line of exposures enters northern Cherokee county, Alabama, 

 from Chattooga of Georgia. The conditions in these petty areas are prac- 

 tically the same with those in the south easterl}- face of Lookout moun- 

 tain, a few miles farther north. The Fort Payne is very thin, 25 feet at 

 the southeast, but becomes 250 feet on Lookout mountain, not more than 

 12 miles away toward the west-northwest. Along this latter line it shows 

 a limestone at the top, very pure, though containing rows of nodular 

 chert. The Bangor is represented by the Oxmoor, which shows no lime- 

 stone along Lookout mountain, though some irregular but rather per- 

 sistent beds are seen farther southeast. Sandstones occur at various 

 horizons, but the persistent beds are at the bottom. The thickness varies 

 from 1,000 to 1,900 feet, the increase being toward the northwest. This 

 line of exposures ends near Gadsden, in Etowah county .f 



A third line of exposures enters De Kalb county from Dade of Georgia, 

 about 6 miles northwest from the last. It is on the northwest side of 

 Lookout mountain, which it separates from Sand mountain, the contin- 

 uation of Waldens ridge. This is Wills valle}^ whence a series of irreg- 

 ular strips extends southwestwardh' through De Kalb, Etowah, Saint 

 Clair, Jefferson, Tuscaloosa, and Bibb counties. The Fort Payne varies 

 with some irregularity. It is 200 to 300 feet in De Kalb, 150 to 275 feet 

 in Etowah and Saint Clair, 250 to 300 feet in Jefferson and Tuscaloosa, 

 but diminishes rapidly to 50 feet in Bibb, where, however, the little 

 patches lie somewhat to the southeast of the principal line of exposures. 

 The lower portion is largely chert, with some crinoidal limestone, but 

 the upj)er portion contains some pure limestone, especially in the north- 

 ern counties. The Bangor limestone, 500 to 600 feet thick, is present in 

 the northern counties, with massive sandstones at the bottom, but is 

 wanting in Jefferson, where the Oxmoor is present, 800 to 1,200 feet thick, 

 and showing the massive sandstone at the bottom overlying a pure lime- 

 stone. The condition is the same in Tuscaloosa, except that the lime- 

 stones seem to be absent. In Bibb county the thickness of the mass 



* Henry McCalley : Geol. Survey ol" Alabama, the Valley regions, vol. ii, pp. 2ii2, 300, ?M, .^^t^ .528, 

 5:50, 531, C.iS, 645, 740, 746. 

 t Henry McCalley, vol. ii, pp. 249, 809 to 812. 

 : Heury McCalley, vol, ii, pp. 172, 183, 184, ,245, 249, 300, 304, 410, 422, 476, 478, 504. 



