The rim rock of the Vieja Rim, the quartz pantellerite of Lord, is named the Bracks Rhyolite. Beneath the Bracks, the "Vieja series" of Vaughn (1900), which is newly subdivided into five formations named, in descending order, the Chambers Tuff, Buckshot Ignimbrite, Colmena Tuff, Gill Breccia, and Jeff Conglomerate, rests unconformably on Upper Cretaceous formations. The Vieja Group is expanded to include also the Bracks and three overlying formations, named, in ascending order, the Capote Mountain Tuff, the Brite Ignimbrite, the Petan Basalt.

The Devonian-Mississippian transition outcrops of central Texas are here described summarily and assigned to a new stratigraphic unit, the Houy Formation. The beds included are mainly Upper Devonian, but partly Lower Mississippian. Locally a basal fraction may be Middle Devonian. Although the deposits included are diverse and their associations complex, the maximum surface thickness so far known is only about 17 feet.

The eastern margin of the High Plains in central western Texas affords particularly good opportunity for study of late Cenozoic geology. The topography of the area is dominated by the southernmost segment of the late Tertiary mantle of fluvial sediments, isolated from the central and northern High Plains by the valley of the Canadian River. The eastern escarpment presents many exposures and the canyons that extend into the plains contain, in addition, a nearly complete sequence of Pleistocene terraces and deposits.

Fourteen black-and-white geologic maps prepared in 1957 and 1959 and obtained from the Department of Geological Sciences, University of Texas, and sold by the Bureau of Economic Geology. Geology compiled by F. L. Whitney; drafted by S. Espey, W. M. Strong, or W. L. Brooks; edited by K. P. Young. 

Fourteen maps are included:

MM0016-A-Austin, NE (Travis and Williamson Counties) 

MM0016-B-Austin, SW (Hays and Travis Counties) 

MM0016-C-Bastrop (Travis County section) 

MM0016-D-Blanco, SE (Hays County)