Dockum Group, undivided (TXTRd;0)

State	Texas
Name	Dockum Group, undivided
Geologic age	Phanerozoic \| Mesozoic \| Triassic-Late
Original map label	TRd
Comments	Well exposed near town of Dockum, Dickens Co., TX. Continental redbed sequence deposited unconformably on Upper Permian (Quartermaster Fm in Tucumcari Sheet (1983). Shale, sandst., siltst., ls., and gravel; mostly shale, miceous, thinbedded, variegated; thickness up to 300 ft. or 400 ft +_ on Lubbock Sheet (1983). correlative with Chinle Fm (above) and Santa Rosa Ss (below).
Primary rock type	fine-grained mixed clastic
Secondary rock type	limestone
Other rock types	conglomerate
Lithologic constituents	Major Sedimentary > Clastic > Mudstone > Shale (Bed) Minor Sedimentary > Clastic > Mixed-clastic > Sandstone-Mudstone (Bed) Incidental Sedimentary > Clastic > Conglomerate (Bed) Sedimentary > Carbonate > Limestone (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	Bureau of Economic Geology, 1983, Tucumcari Sheet, Geologic Atlas of Texas, Bureau of Economic Geology, University of Texas at Austin, scale 1:250,000. Finch, W.I., 1988, Description of the principal reference for the Santa Rosa Formation, Chapter A, in Principal reference section for the Santa Rosa Formation. . ., Guadalupe County, New Mexico: U.S. Geological Survey Bulletin 1804, p. 1-10. [http://pubs.er.usgs.gov/publication/b1804] Bureau of Economic Geology, 1983, Lubbock Sheet, Geologic Atlas of Texas: University of Texas at Austin, Bureau of Economic Geology, scale 1:250,000. Bureau of Economic Geology, 1976, Hobbs Sheet, Geologic Atlas of Texas: University of Texas at Austin, Bureau of Economic Geology, scale 1:250,000.
Geographic coverage	Andrews - Armstrong - Borden - Briscoe - Coke - Crane - Crosby - Dawson - Deaf Smith - Dickens - Ector - Fisher - Floyd - Garza - Howard - Kent - Loving - Lubbock - Lynn - Martin - Midland - Mitchell - Motley - Nolan - Randall - Reeves - Scurry - Sterling - Stonewall - Upton - Ward - Winkler