This report details the occurrence, geometries, scarp morphology, and paleorupture histories of Quaternary faults of northwest Trans-Pecos Texas and northern Chihuahua, Mexico. This study area encompasses a part of the east margin of the Southern Basin and Range-Rio Grande rift tectonic province. Pre-Cenozoic tectonism and its influence on the Cenozoic structural history is also reviewed. Basins studied include the Hueco, Red Light, Northwest and Southeast Eagle Flat, Green River, Salt, Wild Horse, Lobo Valley, and Ryan Flat Basins.

The Leonardian Spraberry Formation is a major oil-producing formation of the Permian Basin, accounting for more than 700 million barrels of oil produced from heterogeneous submarine-fan reservoirs. Extensive exploration and development of the Spraberry and deeper reservoirs provide the opportunity to establish the sedimentary evolution of a fan cone fed only by relatively small rivers and windblown sediment in a tectonically inactive setting.