McAlester Formation (OKPAm;0)

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	Phanerozoic \| Paleozoic \| Carboniferous Pennsylvanian-Middle
Original map label	IPm
Comments	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)
Primary rock type	shale
Secondary rock type	sandstone
Other rock types	coal
Lithologic constituents	Major Sedimentary > Clastic > Sandstone (Bed) Sedimentary > Clastic > Mudstone > Shale (Bed) Incidental Sedimentary > Coal (Bed)
Map references	Heran, W. D., Green, G. and Stoeser, D. B., 2003, A Digital Geologic Map Database of Oklahoma: U. S. G. S. Open File Report 03-247
Unit references	Heran, W. D., Green, G. and Stoeser, D. B., 2003, A Digital Geologic Map Database of Oklahoma: U. S. G. S. Open File Report 03-247 Hart, D.L., 1974, Reconnaissance of the water resources of the Ardmore and Sherman quadrangles, southern Oklahoma: Oklahoma Geological Survey, Hydrologic Atlas 3, scale 1:250,000, 4 sheets. (Geology on sheet 1 compiled by D.L. Hart, and R.O. Fay, in 1970.) Cederstrand, J.R., 1996a, Digital geologic map of Ardmore-Sherman quadrangles, south-central Oklahoma: U.S. Geological Survey Open-File Report 96-370, (3 diskettes), URL address is: http://ok.water.usgs.gov/gis/geology [http://ok.water.usgs.gov/gis/geology/ardmore.html] [http://ok.water.usgs.gov/gis/geology] Marcher, M.V. and Bergman, D.L., 1983, Reconnaissance of the water resources of the McAlester and Texarkana quadrangles, southeastern Oklahoma: Oklahoma Geological Survey, Hydrologic Atlas 9, scale 1:250,000, 4 sheets. (Geology on sheet 1 compiled by M.V. Marcher and D.L. Bergman, in 1971 and revised by R.O. Fay, in 1978.) Cederstrand, J.R., 1996h, Digital geologic map of McAlester-Texarkana quadrangles, southeastern Oklahoma: U.S. Geological Survey Open-File Report 96-377, (3 diskettes), URL address is: http://ok.water.usgs.gov/gis/geology [http://ok.water.usgs.gov/gis/geology/mcalestr.html] [http://ok.water.usgs.gov/gis/geology] Taff, J. A., 1899, Geology of the McAlester-Lehigh coal field, Indian Terri- tory: U.S. Geological Survey, 19th Annual Report, pt. 3, p. 429-456. [http://pubs.er.usgs.gov/publication/ar19_3]
Geographic coverage	Atoka - Coal - Latimer - Le Flore - Pittsburg - Pontotoc