Geoarchaeology of the Salinas de Chao Paleo-embayment

Elizabeth Olson

July 17 – July 20, 2011

Funding Support:  National Geographic Society, Dan & Betty Churchill Fund, & Marshall Cloyd

The Chao paleo-embayment is located just south of the Chao River mouth. A relict escarpment with a log-spiral beach plan-view marks the paleo-embayment. The elevated surface surrounding the escarpment is littered with archaeological sites. Today the paleo-embayment is a flat Salinas environment devoid of life.  It is hard to imagine that this harsh desert environment with temperatures reaching into the 80 degrees Fahrenheit range even during austral winter once supported a large Preceramic population. In order to understand changes in the archaeological record an accurate environmental record is essential. By dating changes in sea level in the paleo-embayment the 2011 field expedition aimed to create such a chronology. My strategy was to find datable organics at the furthest point of inundation along the paleo-embayment by digging trenches at the interface between the escarpment and the paleo-embayment. In doing so the project aimed to better understand past environmental conditions in this area as well as how the timing of changes in this environment coincided with changes in human occupation of the area.

The National Geographic Society, the Churchill Fund, and a generous donation by Marshall Cloyd funded the project, which took place July 17th through July 20th 2011.   I conducted a survey of the escarpment and directed the excavation of several test pits along the apex of the paleoembayment’s escarpment, where datable organics were recovered.  Samples of both the organics and soil were shipped back to the University of Maine under a USDA soil permit (permission provided by Dr. Ann Dieffenbacher-Krall) and are currently stored in the Paleoecology Research Laboratory at the University of Maine. In the coming months the soil samples will be sorted for ecological indicators such as diatoms and the organic material will be sent off for radiocarbon dating.

Summer 2011 Field Season Report: