Expansion in this an element of the Rio Grande rift began about 36 million years back. Rock debris that eroded through the developing highlands that are rift-flank in addition to wind-blown and playa pond deposits, accumulated within the subsiding Mesilla Basin. These fill that is basin, referred to as Santa Fe Group, are 1500 to 2000 legs dense beneath Kilbourne Hole (Hawley, 1984; Hawley and Lozinsky, 1993). The uppermost sand, silt, and clay for the Pliocene to very very early Pleistocene Camp Rice development, the unit that is youngest associated with Santa Fe Group in this the main basin, are exposed into the base of Kilbourne Hole. The Camp Rice development ended up being deposited with a south-flowing river that is braided emptied in to a playa pond within the vicinity of El Paso.

The Los Angeles Mesa area, a flat working surface that developed along with the Camp Rice development, represents the utmost basin fill regarding the Mesilla Basin at the conclusion of Santa Fe Group deposition about 700,000 years back (Mack et al., 1994). This area is approximately 300 ft over the contemporary Rio Grande floodplain. (mais…)