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National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Georgetown Limestone*
  • Modifications:
    • Mapped 1:62.5k
  • Dominant lithology:
    • Limestone
  • AAPG geologic province:
    • Permian basin
Publication:

Freeman, V.L., 1964, Geologic map of the Indian Wells quadrangle, Terrell and Brewster Counties, Texas: U.S. Geological Survey Miscellaneous Investigations Series Map, I-395, 1 sheet, scale 1:62,500


Summary:

Is formation mapped in eastern Brewster and southwest Terrell Cos, TX in Permian basin. Overlies Kiamichi? Formation; underlies Grayson Formation. Map unit described as light-gray to light olive-gray, thin- to very thick-bedded limestone and dolomitic limestone mostly very finely to finely crystalline, a few beds near top of unit not visibly crystalline; fossiliferous; contains gray to reddish-brown chert as nodules, sheets along bedding planes, and replaced fossils. Weathering produces medium-gray to grayish-orange coating that is more resistant and less porous than unweathered rock; solution openings and rillenstein common. Thickness 450 to 600 ft. Age is Early Cretaceous.

Source: GNU records (USGS DDS-6; Denver GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Georgetown Formation
  • Modifications:
    • Areal extent
  • Dominant lithology:
    • Limestone
    • Shale
  • AAPG geologic province:
    • Ouachita folded belt
Publication:

Barnes, V.E. (project director), 1974, Geologic atlas of Texas, Seguin sheet: University of Texas-Austin, Bureau of Economic Geology Geologic Atlas of Texas, 1 sheet, scale 1:250,000, Donald Clinton Barton memorial edition


Summary:

Georgetown Formation. Limestone with some shale; limestone mostly fine-grained, argillaceous, nodular, moderately indurated, light gray; shale, calcareous, soft, light gray to yellowish gray. Thickness 10 to 45 feet. Overlies Edwards Limestone (Lower Cretaceous); underlies Del Rio Clay (Lower Cretaceous). Age is Early Cretaceous.
Not separately mapped. [Present in Hays Co., southeastern TX.]

Source: Modified from GNU records (USGS DDS-6; Denver GNULEX).


For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

Asterisk (*) indicates published by U.S. Geological Survey authors.

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

Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).

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