Middle and Upper Pennsylvanian (Atokan-Missourian) strata in the Colorado River Valley of Central Texas
Robert C. Grayson, Jr., E. L. “Jack” Trite, 1988. "Middle and Upper Pennsylvanian (Atokan-Missourian) strata in the Colorado River Valley of Central Texas", South-Central Section of the Geological Society of America, O. T. Hayward
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The Middle and Upper Pennsylvanian stratigraphic sequence of Central Texas is exposed in a triangular shaped region that is bisected by the Colorado River (Fig. 1). This succession of strata (Fig. 2) is illustrated in this double-site guide. Site 78 begins in San Saba County near Bend, Texas, where exposures of the Marble Falls Limestone, Smithwick Shale, and lower “Strawn” Group are available for study. Three additional localities in San Saba and Mills counties permit special emphasis on the depositional character of the lower “Strawn” Group. The upper Strawn Group, Site 79, is seen along a transect across the outcrop belt in San Saba and McCulloch Counties. Single localities at opposite ends of the outcrop belt in San Saba and Brown Counties (Fig. 1) further document the various lithologies and stratigraphic relationships of the upper unit.