Several microearthquake recording stations were operated as a network in the East Texas Basin beginning in June 1981. At least six certain and two probable earthquakes as well as hundreds of events of undetermined origin were recorded through August 1982. Three of the earthquakes were felt by people in East Texas, including one earthquake and an aftershock at Jacksonville and one earthquake near Center. The Jacksonville earthquake and the Center earthquake were recorded at enough stations to be located instrumentally.

Correct interpretation of the effect of basin infilling on salt mobilization is critical to understanding salt dome growth and stability. The size of salt structures in the East Texas Basin is determined by the original thickness of the underlying Louann Salt (Middle Jurassic). That is, salt structures distinctly increase in size toward the interior of the basin. Initial movement of salt apparently occurred in the marginal areas of the basin during Smackover (Late Jurassic) deposition.

Oversize color geologic map that depicts the surface geology of Dallam County and parts of Sherman, Moore, and Hartley Counties, Texas. The 6-page booklet indicates geologic formations, abbreviations, and ages.

Characterization of 500 of the largest Texas oil reservoirs permits grouping into plays of similar geology and common engineering and production attributes. Most of the major oil reservoirs of Texas are included in 48 plays, which account for 71 percent (32 billion barrels cumulative) of all historical production in Texas. Twenty-seven oil plays lie north and west of the Marathon-Ouachita structural front in Paleozoic reservoirs that are predominantly dolomite and that contained 73 percent of the original oil in place (OOIP) in Texas.