Gaptank Formation (TXPAgt;0)

State	Texas
Name	Gaptank Formation
Geologic age	Phanerozoic \| Paleozoic \| Carboniferous Pennsylvanian-Early Pennsylvanian-Middle Pennsylvanian-Late
Original map label	IPgt
Comments	(fr. Fort Stockton Sheet, Geol. Atlas of Texas, 1982) upper 800 ft thick layers of limestone interbedded with sandst. and shale, followed downward by 900 ft of interbedded sandst., shale, and coarse conglomerate and a basal 100-ft-thick fossiliferous limestone; thickness of formation 1,800 ft.
Primary rock type	fine-grained mixed clastic
Secondary rock type	limestone
Other rock types	conglomerate
Lithologic constituents	Major Sedimentary > Carbonate > Limestone (Bed) Sedimentary > Clastic > Mixed-clastic > Sandstone-Mudstone (Bed)
Map references	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
Unit references	Plummer, F.B., and Moore, R.C., 1921, Stratigraphy of the Pennsylvanian formations of north-central Texas: University of Texas Bulletin 2132. Ross, C.A., 1952, The Wolfcamp Series (Permian) and new species of fusulinids, Glass Mountains, Texas: Journal of the Washington Academy of Sciences, v. 49, no. 9, p. 299-316. Bureau of Economic Geology, 1982, Fort Stockton Sheet, Geologic Atlas of Texas, University of Texas at Austin, scale 1:250,000. Cooper, G.A., and Grant, R.E, 1972, Permian brachipods of West Texas, I, in Smithsonian Contributions to Paleobiology no. 14.
Geographic coverage	Brewster - Pecos