USGS Visual Identifier
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Geologic Unit: Dockum

Dockum Group (CO*,KS*,NM*,TX*)
Dockum Formation (NM*,OK*,TX*)
Dockum Formation of Chinle Group (TX)

Triassic, Middle* (local)
Triassic, Late*

Geologic Province:
Permian basin*
Las Vegas-Raton basin*
Palo Duro basin*
Sierra Grande uplift*
Anadarko basin*
Areal Extent:

Type Locality:
Not designated. Well exposed in vicinity of town of Dockum, Dickens Co., TX. Named from Dockum (Cummins, 1890).

GROUP STATUS (alphabetical): Baldy Hill Formation (CO,NM), Chinle Formation (CO*,NM*,TX), Santa Rosa Formation (NM*,TX*) or Santa Rosa Sandstone (NM*), Sheep Pen Sandstone (NM), Sloan Canyon Formation (CO,NM), Tecovas Formation (TX*), Travesser Formation (CO,NM), Trujillo Formation (TX*) or Trujillo Sandstone (NM,TX).
FORMATION STATUS (alphabetical): Bull Canyon member (informal) (TX), Camp Springs Member (TX), Cooper Member (TX) or Cooper Shale Member (TX), Iatan Member (TX), Tecovas Member (TX), Trujillo Member (TX).

Unit Name History:
Named (Cummins, 1890).
Revised (Gould, 1907; Parker, 1933).
Overview (McLaughlin, 1954).
Revised, divided into Baldy Hill, Travesser, and Sloan Canyon Formations, and Sheep Pen Sandstone; Overview (Baldwin and Muehlberger, 1959).
Overview (Barnes, 1967; 1976; 1983).
Mapped in Colfax Co., NM (Staatz, 1986).
Revised, divided into Tecovas, Trujillo, Cooper members; Overview (Chatterjee, 1986).
Not used (Lucas and others, 1987).
Age modified locally (Finch, 1988).
Not used (Lucas and Hunt, 1989).
Revised, Iatan member named (Lucas and Anderson, 1993) [See entry under Iatan].

Note: If you need more information, please contact Nancy Stamm (
Asterisks (*) indicate usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" implies that a name has been abandoned or that it has fallen into disuse. Former usage and, if known, replacement name given in parentheses ().

Slashes (/) indicate unit name usage violates the 1983 North American Stratigraphic Code. This violation may be explained within brackets ([ ]).

U.S. Department of the Interior, U.S. Geological Survey, Reston, VA, USA
Database project personnel
Last modified: 15-Jan-2013