McAlester Formation

ARDMORE-SHERMAN- Shale, gray, with "Upper Hartshorne coal" 1 to 50 feet above base, 500 to 600 feet thick; overlain by dark-gray shale with many buff fine-grained sandstones, 595 to 1,030 feet thick; overlain by dark-gray shale, 300 to 925 feet thick, with "McAlester coal," 1 to 3 feet thick, a few feet above base. Total thickness ranges from 1,150 to 2,420 feet. (Lower Franks Conglomerate). McALESTER TEXARKANA- Shale, gray, illitic, chloritic, with many tan to gray sandstones, fine- to coarse-grained, micaceous, quartzose; "McAlester and Stigler coals" 600 to 800 feet or more below top; thickness, 2,000 to 2,830 feet, increasing eastward.
State Oklahoma
Name McAlester Formation
Geologic age Middle Pennsylvanian
Lithologic constituents
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Clastic > Mudstone > Shale (Bed)
Sedimentary > Coal (Bed)
Comments First published use in Pittsburg Co, OK, in the Arkoma basin. Probably named for the town of McAlester. No type locality designated. Occurs in the McAlester coal district in the McAlester quadrangle, and in the Lehigh coal district in the Atoka and Colgate quadrangles. In the McAlester coal district, consists of (ascending): 1) 800 ft of shale, with thin sandstone and coal, and Hartshorne or Grady coal occurring near base of shale; 2) three to four beds of sandstone separated by shale 100-200 ft thick, together this sandstone and shale is 500 ft thick; and 3) 700 ft of shale with the McAlester coal about 50 ft above its base--shale is blue, gray, or black with the gray color predominant. In the Lehigh coal district, consists generally of cherty sandstone beds and two workable coal beds. (Taff, 1899).
NGMDB product
Counties Atoka - Coal - Latimer - Le Flore - Pittsburg - Pontotoc