Influences of eolian and pedogenic processes on the origin and evolution of desert pavements

Well-developed desert pavements are present above eolian deposits that mantle flows of the Cima volcanic field, located in the Mojave Desert, California. Soil-stratigraphic data and geochemical data demonstrate that eolian and pedogenic processes play major roles in the evolution of these pavements. Eolian dust (1) accelerates mechanical fragmentation of flow rock, providing the source material for pavements, and (2) accumulates slowly below basaltic colluvium in flow depressions, eventually promoting development of cumulate soils below the evolving stone pavement. An increase in dust flux during the Holocene has raised ancient Pleistocene pavements as much as 20 cm above the former land surface. The results of our studies demonstrate for the first time that most desert pavements do not form by deflation, by overland flow, or by upward migration of stones through a slowly formed, clayey argillic horizon. Desert pavements are born and maintained at the surface.