|Name||Grindstone Creek Formation, expanded|
|Geologic age||Pennsylvanian; Des Moines Series|
Sedimentary > Clastic > Mudstone > Shale > Black-shale (Bed)gray shale, locally sandy and silty
Sedimentary > Carbonate > Limestone (Bed)Brannon Bridge Limestones with 10 ft of shale between
Sedimentary > Clastic > Sandstone (Bed)
|Comments||shale, in part sandy, contains local coal beds and sandstone lentils, gray, thickness of the exposed part of Grindstone Creek Formation, 225 ft. Buck Creek Ss. is top part of the map unit and is coarse-grained, massive, reddish-brown, forms prominent scarp, thickness about 30 ft; Brannon Bridge Limestones in lower part of map unit, fine-grained, some interbedded shale, dark chert lenses, bedding uneven, indistinct to medium gray units as much as 15 ft thick, form scarps and broad dip slopes; about 10 ft of shale separates the two limestone units.|
|Stratigraphic units||Strawn Group, Buck Creek Sandstone, Brannon Bridge Limestones|
Plummer, F.B., and Hornberger, J., Jr., 1936, Univ. Texas Bull. 3534, p. 16.
Bureau of Economic Geology, 1972, Dallas sheet, Geologic Atlas of Texas, Bureau of Economic Geology, University of Texas at Austin, 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||Erath - Palo Pinto - Parker|