The project were (1) test the eolian/pedogenic accretionary model of desert pavement formation by cosmogenic 3He exposure age dating at selected study sites in the Mojave Desert and Great Basin of western North America and in the Atacama Desert of South America; (2) elucidate the types of pedogenic (e.g., vesicular A horizon formation), physical (e.g.,soil deformation and particle movement) and biological (e.g., clast displacement due to plant growth) processes operating on and modifying pavements by field and laboratory investigations; and (3) establish a potential terrestrial analog for planetary studies of ancient Martian regolith development. Initial cosmogenic 3He surface exposure ages on clasts from pavements developed on basaltic lava flow surfaces confirm that clasts have remained at the pavement surface since the eruption of the lava flow. Traditional and experimental methods of soil deformation and clast movement in 3-D space will be accomplished at selected study plots using subsurface and surface measurements. These data sets will be compared with (1) soil profile properties and development within the study plots, (2) chemical weathering parameters on clasts from the pavement and at various levels within the subsurface, and (3) plant transect and trench data showing relations between plant distribution and pavement properties and bioturbation and clast concentrations in the eolian accretionary mantle. This research will help the endeavors of field geologists who use pavements for mapping purposes, geomorphologists and geochronologists who use pavements for dating landscapes, archaeologists who examine cultural artifact distribution on pavements, Quaternary geologists who reconstruct paleoenvironments of land surfaces in desert regions of the world, and planetary geologists who seek terrestrial analogs for the evolution of the Martian regolith.
