New Mexico Geological Society Annual Spring Meeting — Abstracts

North-south hillslope asymmetry is exhibited in a drainage basin incised into the pediment and associated alluvium of the Los Pinos Mts. Microclimate variations with aspect and slope appear to be related to hillslope morphology, and variations in soil development, weathering, and vegetation cover may lead to differences in landscape evolution. To test this hypothesis, catenas are being examined at several stages of hillslope evolution from initial incision to a mature hillslope. Here the types and rates of weathering of the Permian limestone, sandstone, and mudstone of the Yeso and Abo Formations are apparently related to moisture availability. North facing slopes, covered by juniper savannah, are steeper and transport-limited with deeper weathering profiles in all bedrock types, and have more extensive soil development including carbonate and gypsum accumulation. South facing slopes, covered by creosote desert shrubland, are divided into segments by outcropping resistant bedrock units which act as local base level controls, with segments being either transport or weathering limited depending on facies. Investigations have suggested that feedbacks between weathering, soil formation, vegetation cover, and hydraulic properties have enhanced the differences in slope morphology over time.