Abstract

Information now available on the stratigraphy and areal distribution of Devonian rocks in the Llano uplift of central Texas is here summarized. Lower, Middle, and probably Upper Devonian rocks occur in this region. In upward succession the named units are the Pillar Bluff limestone and the Stribling, Bear Spring, and Zesch formations. The last two names are new with the present paper. The rocks are principally calcareous; but the Stribling and Bear Spring formations contain chert, and the Zesch formation is highly siliceous. Some unnamed calcareous, calcareophosphatic, and siliceous rocks of Devonian and probable Devonian age are also described. All the units recognized appear to be thin and patchy in distribution. Except for outcrops of the Stribling formation, known occurrences are mostly fillings in solution structures of various sorts. Devonian rocks are now known from all quarters of the Llano uplift, where their presence was generally unknown previous to June 1945.

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