2016-09-14 Amundson - ARF Brownbag
Channel: Archaeological Research Facility, UC Berkeley
Date: 2019-10-12

Timing and magnitude of paleolakes in the Atacama Desert during Late Quaternary and its implication for the initial human colonization of South America (ARF Brownbag)
Speaker: Ronald Amundson (Environmental Science, Policy and Management, UC Berkeley)
The hyperarid Atacama Desert has long served as a natural barrier to human dispersal. Paradoxically, some of the earliest known archaeological sites in the Western Hemisphere, dating from the late Pleistocene, are found in what is now an absolute (lifeless) desert. It has been determined that these occupations were sustained by perennial fluvial activity and biologically productive riparian ecosystems due to runoff from the western slope of the Andes. The waxing and waning of human occupation is tied to the temporal changes in this water flow. To date, the hydrological changes required to sustain this water flow, and the changes in the entire drainage system – particularly basins – has not been explored. 
Here, we examined present day salt-covered playas that serve as the termination of regional hydrological flow, finding that these were fresh water lakes and marshlands during the Central Andean Pluvial Event (CAPE) that occurred during the late Pleistocene and Early Holocene. We performed field descriptions and radiocarbon analysis of stratigraphic profiles on both paleo-shorelines and lacustrine deposits that lie within the Pampa del Tamarugal (PDT) basin. We identified the collected gastropods, plant remnants, phytoliths and diatomea, which provide a reliable source for paleoenvironmental facies interpretation. 
These data clearly indicate that a paleolake existed at the location of the present-day Salar de Bellavista, and that wetlands or lakes were present at the Salar de Llamara and Pintados. These past aquatic systems are coeval with the activation of the riparian systems of the PDT reported by previous studies. These lakes would have contributed to a starkly different set of resource constraints for early inhabitants than the inhospitable conditions that exist today. Additionally, the presence and projected geographical outline of these water resources provides guidance in the search for additional evidence of human occupation in the region, and for understanding the geographical connections that existed among these earliest inhabitants of the Western Hemisphere.