The surface units that comprise the Trinity Group of southwestern Arkansas have been given various levels of lithostratigraphic classification since H. D. Miser and A. H. Purdue conducted their surveys of the DeQueen and Caddo Gap quadrangles 66 years ago. Currently, the Lexicon of Geologic Names of the United States lists six formations in the area. From the base of the Trinity Group to the top, they are: (1) Pike Gravel, (2) Delight Sand, (3) Dierks Limestone, (4) Holly Creek Formation, (5) DeQueen Formation, and (6) Antlers Sand.

Our study of the Trinity Group in southwestern Arkansas supports the view that the three lower units should be regarded as members of one formation. This proposal was made initially in a 1956 doctoral dissertation by P. H. Nichols, who recommended that the name "Provo Formation" be adopted. The name "Provo," however, has been assigned to another formation of late Tertiary age in Utah. We suggest that the name "Cossatot Formation" be used for the strata described by Nichols. The name is taken from the Cossatot River, which flows west of the type locality in Sevier County, Arkansas.

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