The top of mushroom-shaped Oakwood salt dome is approximately 210 m (700 ft) beneath the boundary of Freestone and Leon Counties near the southwestern end of the East Texas Basin, The dome is surrounded by Jurassic, Cretaceous, and lower Tertiary marine and nonrnarine strata. A salt pillow initially formed in Late Jurassic “Smackover” time, when faulting contributed to uneven sediment loading of the Louann Salt.

Lignite deeper than 200 ft (61 m) constitutes about 60 percent of the total lignite resources in Texas. Projections indicate that meeting future demand will require mining this deep-basin lignite. However, because the principal lignite host, the Eocene Wilcox Group, is also a major fresh-water aquifer, deep-basin lignite development by surface mining or underground gasification poses unanswered questions concerning hydrogeologic feasibility and environmental impacts.

The search for oil, its development, production, and marketing have, for the better part of a century, been a fundamental part of the Texas economy. The history of Texas oil finders, from the self-educated wildcatter to the highly trained explorationist, is a part of Texas lore.

The San Andres evaporitic sequence in the Palo Duro Basin comprises several thick carbonate units in its lower part and many thin units in its upperpart. To the south, across the Northern Shelf of the Midland Basin, evaporites pinch out and carbonates predominate. Six lithofacies were differentiated in the Palo Duro and Northern Shelf carbonates: dolomudstone, pellet-oolite packstone-grainstone, filamentous (Girvanella-like) grainstone, sponge spicule packstone, wispy-laminated crinoid packstone, and skeletal packstone-grainstone.