|Pottsville Formation, Black Warrior Basin, Alabama/Mississippi
The Lower Pottsville strata (800 to 1,000 ft thick) contain orthoquartzitic sandstone, shale, and coal interpreted as the deposits of barrier-bar, tidal-flat, and lagoonal sediments in a north-northeast progradational system of a massive clastic wedge shed from the Ouachita orogen (Cleaves and Broussard, 1980). The Upper Pottsville consists of lithoarenite, shale, coal, and minor amounts of orthoquartzite and represents a lateral gradation from lower delta-plain distributary channels, to interdistributary bays, to a barrier bar. The Lower and the Upper Pottsville sediments were deposited in two different delta systems (Horsey, 1981). The Pottsville in the north is exposed and has been eroded as a result of upwarping of the Nashville Dome. Approximately 35 separate coal beds occur in the Pottsville Formation; most are fairly local seams, but few are extensive and have been used to define seven coal groups in the Upper Pottsville. Several authors have stratigraphically divided the Pottsville; however, because of limited information, we have characterized the whole interval.
Cleaves, A., and Broussard, M., 1980, Chester and Pottsville depositional systems, outcrops and subsurface, in the Black Warrior Basin: Gulf Coast Association of Geological Societies Transactions, v. 30, p. 49–59