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. Although the validity of the interpretation may be questioned, it is anticipated that the interpretation will focus attention on the problems and limitations of facies interpretation in basin analysis.

The Texas Coastal Zone is marked by diversity in geography, resources, climate, and industry. It is richly andowed with extensive petroleum reserves, sulfur and salt, deep-water ports, intracoastal waterways, mild climate, good water supplies, abundant wildlife, commercial fishing resources, unusual recreational potential, and large tracts of uncrowded land in close proximity to major population centers.

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). With continued growth, annual production exceeded 160,000 tons in 1968, making the district second only to New York State in national output, Moderate- to large-sized deposits have been developed with near-surface parts inexpensively extracted. Talc reserves are estimated in the tens of millions of tons.