A multi-disciplinary project is proposed to determine how variations in climate, dust flux, and lithology are genetically linked to soil-landscape evolution on alluvial fans in desert environments. Important variables can be examined because the study area contains an arid to semi-arid climatic gradient, an independent record of Quaternary climate change and dust flux, excellent chronostratigraphic resolution, and sequences of lithologically distinct deposits (granite, limestone, mixed). The project objectives are to: determine variation in rates of soil- geomorphic processes among different lithologies, determine spatial and temporal changes in dust flux, climate, surface permeability, and soil-water balance, and determine how changes in these factors control formation of calcic soils. Soil-geomorphic properties related to spatial and temporal changes in climate and dust flux will be documented through field descriptions and laboratory analysis of soils, morphometric measurements of fan-surfaces, and evaluation of soil and fan-surface hydrology. A novel approach of this study will be to integrate empirically measured soil- geomorphic properties with computer simulations of soil water movement and pedogenic accumulation of carbonate. Isotopic studies of soil carbonate will provide additional information concerning the timing and processes of calcic soil formation and paleoclimate. Results will provide information for developing criteria for recognition of signals of climatic change preserved in soil- geomorphic systems, for evaluating the effect of climate change on the rates of soil-geomorphic components commonly used for age estimations, and for developing regional stratigraphic correlations to other Quaternary deposits in the southwest U.S.
