Perennial stream discharge in the hyperarid Atacama Desert of northern Chile during the latest Pleistocene.

A large fraction of the vital groundwater in the Atacama Desert of northern Chile is likely composed of "fossil" or "ancient" reserves that receive little or no recharge in today's hyperarid climate. Here, we present evidence for latest Pleistocene perennial streamflow in canyons from the hyperarid core of the Atacama Desert in northern Chile. Fluvial terraces in the Pampa del Tamarugal (PdT) basin (21 degrees S) contain widespread fossil wood, in situ roots, and well preserved leaf litter deposits indicative of perennial surface flow currently absent in these channels.