Dockum Group, undivided (TXTRd;0)

State	Texas
Name	Dockum Group, undivided
Geologic age	Late Triassic
Lithologic constituents	Major Sedimentary > Clastic > Mudstone > Shale (Bed) Minor Sedimentary > Clastic > Mixed-clastic > Sandstone-mudstone (Bed) Incidental Sedimentary > Carbonate > Limestone (Bed) Sedimentary > Clastic > Conglomerate (Bed)
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).
Stratigraphic units	basal unit Santa Rosa Formation (Sandstone), ascending units are Tecovas Formation, Trujillo Formation, Chinle Formation
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. https://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. 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. 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.
NGMDB product	NGMDB product page for 68390
Counties	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

State

Texas

Name

Dockum Group, undivided

Geologic age

Late Triassic

Lithologic constituents

Major

Sedimentary > Clastic > Mudstone > Shale (Bed)

Minor

Sedimentary > Clastic > Mixed-clastic > Sandstone-mudstone (Bed)

Incidental

Sedimentary > Carbonate > Limestone (Bed)

Sedimentary > Clastic > Conglomerate (Bed)

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).

Stratigraphic units

basal unit Santa Rosa Formation (Sandstone), ascending units are Tecovas Formation, Trujillo Formation, Chinle Formation

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.

https://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.

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.

NGMDB product

NGMDB product page for 68390

Counties

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