Late Holocene Alluviation in the Palomas Basin, South-Central New Mexico

Geology of the Eastern Plains of San Agustin and Upper Alamosa Creek

“…In Alamosa Creek, incision may have also been facilitated by river base level drops downstream of the upper Alamosa basin, since the Rio Grande system was incising in southern New Mexico since 800-900 Ma (e.g., Mack et al, 1993Mack et al, , 1998Mack et al, , 2002McCraw and Williams, 2012). In many areas of southern New Mexico, notable incision occurred at the height of the last glacial maximum, and backfilling occurred in the transition to warmer climates 15,000 to 5,000 years ago (e.g., Gile et al, 1981;Jochems and Koning, 2015). This backfill consists largely of sand and gravel, with subordinate silty or clayey sand.…”