|Name||Thrifty and Graham Formations, undivided|
|Geologic age||Late Pennsylvanian; Virgil Series|
Sedimentary > Clastic > Mudstone > Shale > Black-shale (Bed)
Sedimentary > Carbonate > Limestone (Bed)limestones more persistent than shale or sandst beds in this map unit
Sedimentary > Clastic > Sandstone (Bed)
|Comments||Unit mapped undivided as basal formation of Cisco Group in SE part of Wichita Falls-Lawton Sheet (1987) on Bend arch (Brown Co.) and Ft. Worth syncline. Unit is equivalent to lower part of Markley Fm of Bowie Group in west part of same map. Mudstone, shale, sandstone, and limestone. Mudst., sandy and silty above Avis Ss; in each of intervals between Avis Ss and Gunsight Ls and Gunsight and Bunger Ls, more silty, sandy, and thinly bedded upward. Mudst gypsiferous, local thin coal seams, bioclastic ls lentils. Sandstone in unit fine to med grained, local pebble conglo., interbds of mudst., channel fill locally, some thin shale intercalated with sheet ss. Limestone fine grained, thin to massive beds, commonly thin bedded with beds separated by thin shale, some beds grade laterally to calcar siltst., marine megafossils and algae, locally bioclastic; thickness commonly 2-3 ft, as much as 8 ft locally; Thickness of Thrifty and Graham Fms undivided 330-490 ft, thickens northward|
|Stratigraphic units||Cisco Group, Blach Ranch Limestone, Ivan Limestone, Avis Sandstone, Gunsight Limestone, Bunger Limestone, North Leon Limestone, Gonzales Creek Member, Gonzales Limestone, Jacksboro Limestone, Cisco Group, Bowie Group (new)|
Plummer, F.B., and Moore, R.C., 1921, Stratigraphy of the Pennsylvanian formations of north-central Texas: University of Texas Bulletin 2132.
Bureau of Economic Geology, 1987, Wichita Falls-Lawton Sheet, Geologic Atlas of Texas: University of Texas at Austin, Bureau of Economic Geology, scale 1:250,000.
Bureau of Economic Geology, 1992, Geologic Map of Texas: University of Texas at Austin, Virgil E. Barnes, project supervisor, Hartmann, B.M. and Scranton, D.F., cartography, scale 1:500,000.
|Counties||Brown - Coleman - Eastland - Jack - McCulloch - Palo Pinto - Stephens - Wise - Young|