Geology of northeastern front of Davis Mountains, Trans-Pecos Texas

Three sides of a topographic basin bordering the northeastern front of the Davis Mountains are flanked by Tertiary volcanic rocks of the McCutcheon group; on the north are gravel-colored pediments. A large post-McCutcheon, pre-Quaternary block-faulted syncline lies along the eastern margin of the basin. Quaternary landslide aprons and pediment gravels cover most of the basin floor, excepting scattered outcrops of Cretaceous bedrock that range in age from Albian to Senonian. Landslide aprons were formed during the Pleistocene epoch by disintegration of toreva blocks that descended during periods of heavy rainfall. Cliffward rotation during descent produced ready-made stream valleys which were deepened and steepened by incising streams to produce an unstable mountain scarp that led to additional landsliding.