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Geologic Unit: Gibbons
Map showing publication footprint
  • Usage in publication:
    • Gibbons conglomerate lentil
  • Modifications:
    • Original reference
  • Dominant lithology:
    • Conglomerate
  • AAPG geologic province:
    • Llano uplift
Publication:

Plummer, F.B., 1945, Stratigraphy of the Lower Pennsylvanian coral-bearing strata of Texas: University of Texas-Austin, Bureau of Economic Geology Publication, no. 4401, p. 63-76.


Summary:

Pg. 65-66. Gibbons conglomerate lentil in Marble Falls formation. A basal conglomerate that marks the contact of the Marble Falls and the Bamett formation in some places. Consists of a dark-gray coarse fossiliferous glauconitic sand containing numerous subrounded cobbles from a fraction of an inch up to 10 inches in diameter; conglomerate grades upward into a coarse sandstone layer about 1 foot thick. Lentil is about 30 feet long east and west, 1 foot thick at each end and about 4 feet in the middle. Age is Early Pennsylvanian (Bend).

Source: US geologic names lexicon (USGS Bull. 1200, p. 1502).


Map showing publication footprint
  • Usage in publication:
    • Gibbons conglomerate member
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Llano uplift
Publication:

Plummer, F.B., 1947, Summary of classification of the Pennsylvanian formations of Texas, with special reference to the Lower Pennsylvanian of the Llano region, IN Wanless, H.R., Symposium on Pennsylvanian problems: Journal of Geology, AAAS meeting, St. Louis, MO, March, 27, 1946, v. 55, no. 3, pt. 2, p. 193-201., Revision of Jour. Paleo., v. 21, no. 2, p. 142-146, 1947. See also GSA Bull., v. 57, no. 12, pt. 2, p. 1273, 1946 [abs.]


Summary:

Pg. 196 (table 2), 197. Gibbons conglomerate member of Big Saline formation. Rank raised to member status in Big Saline formation. East of Ridge Cavern, underlies Aylor member; west of Ridge Cavern, underlies Brook Ranch member. Age is Early Pennsylvanian (Bend).

Source: US geologic names lexicon (USGS Bull. 1200, p. 1502).


Map showing publication footprint
  • Usage in publication:
    • Gibbons conglomerate lentil
    • Gibbons conglomerate member
  • Modifications:
    • [Principal reference]
    • Revised
  • AAPG geologic province:
    • Llano uplift
Publication:

Plummer, F.B., 1950, Carboniferous rocks of the Llano region of central Texas: University of Texas-Austin, Bureau of Economic Geology Publication, no. 4329, 170 p.


Summary:

Pg. 61-62, 63. At type section, the Gibbons is thin pebble conglomerate 6 to 12 inches thick. Age is Early Pennsylvanian (Bend).
Type section: 0.25 mi north of San Saba-Brady Road, on the Gibbons Ranch, 2.5 mi south of Hall, San Saba Co., central TX.

Source: US geologic names lexicon (USGS Bull. 1200, p. 1502).


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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