The suitability of salt domes in the east Texas basin (Tyler basin), Texas, for long-term isolation of nuclear wastes is being evaluated. The major issues concern hydrogeologic and tectonic stability of the domes and potential natural resources in the basin.

Five distinct facies are recognized in the Eocene Queen City exposures between the Trinity River valley and the Louisiana state boundary. These facies (fluvial, deltaic, tidal flat, barrier, and tidal delta) display diagnostic suites of physical and biogenic structures.

Lignite development will place major demands on ground-water supplies. The Simsboro Formation and the Calvert Bluff Formation (a major lignite-bearing unit) of the Wilcox Group between the Colorado and Trinity Rivers constituted a test case to evaluate the availability and quality of ground water.

Secondary leached porosity is common to dominant in near surface to deep subsurface lower Tertiary sandstone reservoirs along the Texas Gulf Coast. This secondary porosity is in the form of leached feldspar grains, volcanic rock fragments, carbonate cements, and carbonate-replaced grains.

Three closely spaced oblique-slip faults displace a Quaternary gravel and sand unit overlying Eocene Claiborne strata in the Trinity River Valley, Leon County. These steeply dipping faults strike east-northeast; two of them are downthrown toward the south, with a smaller, antithetic, central fault downthrown to the north.