The Allamoore district of Hudspeth and Culberson counties, Texas, has become one of the most significant talc-producing areas of the United States. Exploitation of talc deposits in the district began in 1952 with a cumulative production of 120,000 tons through 1957 (Flawn, 1958).

The Texas Coastal Zone is marked by diversity in geography, resources, climate, and industry.

This field guide is designed to provide an opportunity to observe a variety of facies that are the fundamental blocks with which principal depositional systems have been fabricated. Available data is provided and a genetic interpretation is proposed.

The Fredericksburg Group is one of three groups of rocks which comprise the outcropping Lower Cretaceous sediments in north central Texas. Four formations form this group; from the base upward these are the Paluxy, Walnut, Comanche Peak and Edwards (fig. 1).

The West Chinati stock, well exposed in San Antonio Canyon and immediately westward on slopes of the southwestern part of the Chinati Mountains, Presidio County, Texas, is a large stocklike body of porphyritic hornblende granite cut by numerous dikes and irregular-shaped plutons of rhyolite, rhyo

Geologic map that depicts surface geology of Tarrant, Dallas, Kaufman, Ellis, Johnson, Somervell, and Rockwall Counties and parts of Parker, Hood, Erath, Bosque, Hill, Navarro, Henderson, Van Zandt, and Hunt Counties, Texas.

Endemic ammonite faunas evolved from cosmopolitan faunas in a series of successive episodes over about 35 million years of the Cretaceous of the Gulf Coast of the United States.