One of the basic mineral resources of Texas is abundant deposits of lignite in Eocene rocks of the Gulf Coastal Plain. Currently, Texas lignites are utilized as sources of industrial fuel, activated carbon and, locally, drilling mud additives; research indicates significant future nonfuel uses of lignite and lignitic coals.

Tropical storms, which cross the Texas coastline with a frequency of 0.67 storms per year, play a major role in nearshore sedimentation on the south Texas coast. Greatest geological effects of these storms are produced by wind-driven waves and by storm surges.

Eagle Mountains and vicinity include three physiographically distinct but stratigraphically and structurally related sub-units: a central, topographically high mesa, Eagle Mountains; a much lower northwestward extension, Devil Ridge; and a south-southeastward extension, Indio Mountains. These highlands, trending generally northwest to north-northwest, are surrounded by "bolsons" or inter- montane basins partly filled with alluvium.