Studies of physiographic relations and of fossil molluscan faunas made in the Pecos River valley region (Val Verde County to the Texas�New Mexico border) reveal extensive, well-pedimented surfaces southwest of the river extending from the Davis Mountains to near the present channel.

This report is a compilation of all available data on mineral resources (exclusive of oil and gas) in 39 south Texas counties. Information from published and unpublished sources was checked and supplemented by field investigations.

The Pemberton Hill-Lewisville (T-2) terrace deposits of the Trinity River in Dallas and Denton Counties are divided into four consecutive members. Sixty-three vertebrates, 32 mollusks, and several insects and plants were collected from 3 members and are discussed in the report. The terrace deposits are tentatively referred to as the Sangamon interglacial on the basis of two radiocarbon dates in excess of 3700 years BP and on the association of the giant bison with a typical interglacial fauna.