|Name||Chico Ridge Limestone|
|Geologic age||Pennsylvanian; Missouri Series|
Sedimentary > Carbonate > Limestone (Bed)
|Comments||On Sherman Sheet of the Geologic Atlas of Texas (1967) unit is mapped as a member of the Graford Formation. The unit's characteristics are similar to Devils Den and Rock Hill Limestone (mbrs of Graford Fm.). Devils Den Ls. Member mostly aphanitic to sparry algal ls., thin to thick bedding, irreg., yell-gray to grayish orange; weathers mottled gray red purple. thins SW and grades to argillaceous, calcitic, fine-grained ss; NE it merges with Rock Hill Ls. to form Chico Ridge Limestone. marine megafossils include brachiopods and crinoid debris. Devils Den Ls. 6-45 ft thick. Rock Hill Ls. Mbr. is granular, brecciated, clasts and fossils weather in relief, thick bedded to massive, hard, earthy conchoidal fracture, ;mottled pale yellowish brn and mod. yellowish brn; marine megafossils, NE merges w/ Devils Den Ls to form Chico Ridge Ls. Rock Hill Ls. thickness 3 ft.|
|Stratigraphic units||Graford Formation|
Bureau of Economic Geology, 1967, Sherman Sheet, Geologic Atlas of Texas: University of Texas at Austin, Bureau of Economic Geology, scale 1:250,000.
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.
|Counties||Jack - Wise|