DESERT PAVEMENT EVOLUTION - AN EXAMPLE OF THE ROLE OF SHEETFLOOD

Patches of young, well-developed desert pavement were found atop bare rock on the Pisgah basalt flow, California. These particular stone mos aics formed directly atop the flow; no soil is present, or ever has be en. Therefore, soil expansion and aeolian processes played no signific ant role in their creation or maintenance. The unusual setting at Pisg ah allows sheetflood to be the sole agent responsible for the lateral movement of surface stones into these mosaics. The Pisgah mosaics thus represent an end-member case of desert pavement types, and they may r epresent a previously unrecognized initial substage of accretionary ma ntle formation.