Georgetown Formation of Central Texas and Its Northern Texas Equivalents

Abstract

The formation in central Texas is 80 feet thick. As it is traced northward the formation is found to thicken to 410 feet at Red River. This total thickness of Georgetown in northern Texas is divided into seven formations. In this paper, the writer traces all northern Texas equivalents in order to determine the exact thickness of each of the northern Texas formations included in central Texas beds. The Main Street formation of northern Texas is represented at Austin by approximately 15-20 feet of limestone ledges in the upper one-fourth of the formation. The Pawpaw formation of northern Texas is lacking in the Austin region. The Weno formation of northern Texas thins, thickens, and again thins southward from Red River and is represented at Austin by approximately 10-15 feet of limestone. The Denton formation of northern Texas is represented at Austin by only a thin ledge of limestone rich with Gryphaea washitaensis Hill. The Fort Worth formation is the best represented of all northern Texas equivalents of the of central Texas, and has approximately 30 feet of Fort Worth sediments at Austin. The Duck Creek formation of northern Texas is traceable southward to Austin, where its thickness is approximately 30 feet. The Kiamichi clay of northern Texas becomes decidedly thinner southward and at Austin is represented by only a few feet of shaly marls.