Lignite deposits in Texas occur in three Eocene stratigraphic units: the Wilcox Group (lower Eocene), the Yegua Formation (upper Eocene), and the Jackson Group (upper Eocene). They are part of an extremely thick Gulf Coast Tertiary clastic sequence composed of an alternation of fluvial-deltaic and marine units. At the outcrop, the marine units are volumetrically insignificant. All units dip coastward at 1/4 deg to 2 deg (about 20 to 180 ft/mile).

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 increasing demand for uranium combined with the improving economics of uranium production have resulted in a significant upsurge in exploration and mining efforts in the South Texas Coastal Plain uranium province. Texas ranks third in U.S. uranium production. Today, potentially commercial deposits have been delineated along an arcuate belt that stretches more than 250 miles from the Rio Grande into the middle Coastal Plain.

In east-central Texas, or the area between the Colorado
and Trinity Rivers, the Wilcox Group (lower Eocene) is divided
into three formations. Up section they are the Hooper,
Simsboro, and Calvert Bluff. At Alcoa and Butler, lower Calvert
Bluff sediments are exposed. The Calvert Bluff Formation
conformably overlies the highly resistive, massive, fluvial Simsboro
Sand and is recognized by its finer grain size, as reflected
in reduced resistivity on normal curves, and by the first

Future utilization of aggregate resources in urban areas must be considered during early planning stages of an urban complex. This is of particular importance because urban land values are commonly greater than the mineral value of these low-unit-value materials, and the use of the land for construction pre-empts exploitation of the aggregate materials. In addition, zoning restrictions may also prohibit resource exploitation of urbanized land.