The Ellenburger of Texas was first defined as a marine limestone formation of Cambrian and Ordovician age (Paige, 1912), but recently it has been subdivided into several formations and the term Ellenburger given group status (Cloud and Barnes, 1948).

Stonewall quadrangle is south of the Llano region and is in the marginal portion of the Edwards Plateau where much of the plateau surface has been destroyed by erosion.

The Blacklands Experimental Watershed, a hydrologic research project of the Soil Conservation Service located about 15 miles southeast of Waco, Texas, is underlain by marls and chalks belonging to the Taylor group of the Gulf series of the Cretaceous system, which, in conformity with the general

New information concerning the ancestry of the later Tertiary horses, Calippus, Protohippus (in the original sense), Hipparion, Neohipparion, and Nannippus, has been obtained from a restudy of the various mammalian farmas of the Coastal Plain in Texas, based in the main on the extensive collectio

The Squaw Creek quadrangle is partly within the Llano region and partly within the Edwards Plateau province.

Zoned and unzoned perthite-quartz-plagioclase-muscovite pegmatites in the form of tabular bodies, irregular bodies with tabular branches, irregular masses, elongate lenses, lit-par-lit zones, and small augen and stringers are distributed throughout the Precambrian metasedimentary rocks of the Mic

A recently discovered buried hill, at least 77 feet high, is composed of strata of the Wilcox group (lower Eocene) and covered on its flanks by cross-bedded sands of the lower Carrizo and at the top by level-bedded shales and silts of the upper Carrizo formation.