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National Geologic Map Database
Geologic Unit: Twin Mountains
Map showing publication footprint
  • Usage in publication:
    • Twin Mountains Formation
  • Modifications:
    • Mapped 1:250k
  • Dominant lithology:
    • Claystone
    • Sandstone
    • Conglomerate
  • AAPG geologic province:
    • Fort Worth syncline
    • Strawn basin
Publication:

Barnes, V.E. (project director), 1987, Geologic atlas of Texas, Dallas sheet [revision of 1972 ed.]: University of Texas-Austin, Bureau of Economic Geology Geologic Atlas of Texas, 1 sheet, [10 p., revised 1988], scale 1:250,000, Gayle Scott memorial edition


Summary:

Twin Mountains Formation. Upper part claystone, middle part sandstone above claystone, lower part mostly sandstone, some claystone and conglomerate. Sandstone, fine- to medium-grained in middle part, medium- to coarse-grained in lower part, sorting best in middle part, friable, locally large scale cross-bedding, mostly light gray, some light brown near middle. Claystone, silty, mostly gray, locally in upper part green, yellow, red. Conglomerate, pebbles of chert and quartz, argillaceous, sandy, gray, brown. Thickness about 150 feet. Lies below Glen Rose Formation and unconformably on Pennsylvanian rocks. Age is Early Cretaceous.
[Mapped in Erath, Hood, Parker, and Somervell Cos., eastern TX.]

Source: Publication.


Map showing publication footprint
  • Usage in publication:
    • Twin Mountains Formation
  • Modifications:
    • Mapped 1:250k
  • Dominant lithology:
    • Sand
    • Clay
    • Conglomerate
  • AAPG geologic province:
    • Fort Worth syncline
Publication:

Barnes, V.E. (project director), 1991, Geologic atlas of Texas, Sherman sheet [revision of 1967 ed.]: University of Texas-Austin, Bureau of Economic Geology Geologic Atlas of Texas, 1 sheet, [17 p.], scale 1:250,000, Walter Scott Adkins memorial edition


Summary:

Pamphlet [p. 6]. Twin Mountains Formation. Sand, clay, and conglomerate; sand, brownish-yellow, locally weathers to red, fine- to coarse-grained, conglomeratic in lower part, thin-bedded to massive, cross-bedded; clay, red, gray, green, silty, thin-bedded to massive; conglomerate composed of chert, quartz, and quartzite clasts. Thickness 175 to 200 feet. [Correlative with lower part of Antlers Sand.] Lies above Permian Petrolia Formation of Wichita Group and below Glen Rose Limestone. Age is Early Cretaceous.
[Mapped southwest of Decatur, in Jack, Parker, and Wise Cos., central northern TX; in southwestern corner of map sheet.]

Source: Publication.


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