In the Rio Grande Embayment of South Texas, the Carrizo Formation (lower Eocene) consists of two sand-rich fluvial depositional systems that grade basinward into several deltaic complexes within the upper part of the Wilcox Group. Data from oil, gas, and water wells provide information on Carrizo fluvial and ground-water flow systems, and outcrop and core data help define component lithofacies.The bed-load channel system contains multistory, multilateral fluvial channel-fill sandstones deposited by broad, sand-rich, dominantly braided streams.
Approximately 2,200 ft (670 m) of principally continental and paralic rocks of late Virgilian, Wolfcampian, and early Leonardian age (late Pennsylvanian and early Permian) are exposed in an area of about 4,950 mi2 (12,800 km2) between the Brazos and Red Rivers in North-Central Texas. The stratigraphic complexity of these strata has impeded internal correlation and mapping ever since the rocks were first described by W. F. Cummins in the late 19th century.
The State-owned submerged lands of Texas encompass almost 6,000 mi2 (15,540 km2). They lie below waters of the bay-estuary-lagoon system and the Gulf of Mexico and extend 10.3 mi (16.6 km) seaward from the Gulf shoreline (fig. 1). The importance of these lands and their resources to resident flora and fauna as well as to people is well known and documented; more than one-third of the state's population is concentrated within an area of the Coastal Zone that is only about one-sixteenth of the state's land area.
Damon Mound salt dome, located in Brazoria County, Texas, is a shallow diaper that has salt less than 600 ft (180 m) and cap rock less than 100 ft (30 m) below the surface. Oligocene through Pleistocene strata thin toward the diapir, and the occurrence of a coralline facies of the Oligocene Heterostegina limestone above the cap rock suggests seafloor relief over the diapir during late Oligocene time. Thickening of Miocene and Plio-Pleistocene strata peripheral to the dome suggests syndepositional salt flow from surrounding salt withdrawal subbasins.
