|Name||Mundy Breccia and Castner Limestone, undivided|
|Geologic age||preCambrian (Proterozoic)|
Sedimentary > Carbonate > Limestone (Bed)Castner Limestone includes hornfels, conglomerate, dolomite, and diabase and is mostly light gray, green, and blue limestone, fine to coarse grained, lt. gray chert lenses, thin bedded, irreg. bedded in upper one-third; metamorphic minerals such as serpentine, tremolite, and garnet abdt in green ls. beds.
Metamorphic > Granoblastic > Hornfels (Hornfels)hornfels present in the upper third of the Castner Limestone, thus is ranked a minor part of the whole map unit (Mundy Breccia and Castner Limestone, undivided). Hornfels very fine grained, dark gray, in many thin beds, laminated and contains a few beds of conglomerate.
Sedimentary > Carbonate > Dolostone (Bed)Dolomite in the basal exposed beds of the Castner Limestone in the Franklin Mtns. The dolomite is white to light gray, one bed contains algal structures
Tectonite > CataclasiteThe Mundy Breccia randomly oriented, black basalt boulders, angular to slightly rounded, in matrix of dark gray mudstone. thickness about 90 ft, as much as 250 ft maximum.
|Comments||Mundy Breccia, randomly oriented, black basalt boulders, angular to slightly rounded, in matrix of dark-gray mudstone; thickness 250 feet maximum. Castner Limestone, limestone, hornfels, conglomerate, dolomite, and diabase. Mostly limestone, fine to coarse grained, light-gray chert lenses, thin bedded, irregularly bedded in upper one-third, light gray, green, blue; metamorphic minerals such as serpentine, tremolite, and garnet abundant in green limestone beds. In upper third, hornfels, very fine grained, numerous thin beds, dark gray, laminated and a few beds of conglomerate. Dolomite in basal part of exposure, white to light gray, one bed contains algal structures. Diabase, dark greenish gray, thin-to-thick sills near base and middle, constitutes about one-third of outcrop. Thickness of formation 1.100+ feet, base not exposed.|
Bureau of Economic Geology, 1968, Van Horn-El Paso Sheet, Geologic Atlas of Texas: Bureau of Economic Geology, The University of Texas at Austin, scale 1:250,000.
Harbour,R.L., 1960, American Association of Petroleum Geologists Bulletin v. 44, no. 11, p. 1788-1790.
Bureau of Economic Geology, 1992, Geologic Map of Texas: University of Texas at Austin, Virgil E. Barnes, project supervisor, Hartmann, B.M. and Scranton, D.F., cartography, scale 1:500,000.