USGS Visual Identifier
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Geologic Unit: Fredericksburg

Fredericksburg Group (AL?,AR?,LA?,NM?,OK,TX*)

Cretaceous, Early*

Geologic Province:
Permian basin*

Areal Extent:

Type Locality:
Named from Fredericksburg, Gillespie Co., TX (Hill, 1887). [From US geologic names lexicons, USGS Bull. 896, 1200]

(alphabetical): Comanche Peak Limestone (TX*) or Comanche Peak Formation (NM), Edwards Limestone (TX*), Gatesville Formation (TX), Goodland Formation (LA,OK,TX) or Goodland Limestone (LA*,OK*,TX*), Kiamichi Formation (LA*,NM,OK*,TX*), Pryor Formation (TX), Telephone Canyon Formation (TX), University Mesa Marl (TX), Walnut Clay (AR*,LA*,OK*,TX*) or Walnut Formation (NM,TX*) or Walnut Marl (OK,TX).

Unit Name History:
Original reference (Hill, 1887a).
Revised (Hill, 1887b, 1890, 1891, 1892, 1894)
Revised; Areal limits (Richardson, 1904).
Revised (Winton, 1925).
Revised (Bybee and Bullard, 1927).
Revised (Alexander, 1929; Redfield, 1929; Cuyler, 1929).
Revised (Armstrong and Scott, 1930)
Revised (Adkins, 1932).
Revised (Thompson, 1935; Mendenhall, 1935).
USGS classification (Wilmarth, 1938).
Mapped in Hudspeth Co., TX (Gillerman, 1953).
Mapped in OK, includes Goodland Limestone and Walnut Clay (Miser and others, 1954).
Revised (Frizzell, 1954).
Overview (Lozo and others, 1959; Perkins, 1960).
Revised in OK, only Goodland Limestone is included (Davis, 1960).
Overview (Barnes, 1976).
[Discrepency in GNU records concerning the areal extent of this unit. USGS DENVER GNU states that the Fredericksburg Group is restricted to Gulf Coast Plain of TX (reference not given). The main GNU file states that this unit also occurs in AL, AR, LA, NM, and OK (references not given).]

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