Context is Everything: Ruppia cirrhosa and Dating the White Sands Footprints

Context is Everything: Ruppia cirrhosa and Dating the White Sands Footprints Dr. Robert Dello-Russo There is a fascinating scientific controversy surrounding the radiocarbon dating of the footprints left by early humans at White Sands National Park. Accurate ages of the footprints are important to our understanding of the Peopling of the Americas so, in this presentation, Dr. Dello-Russo will focus on several factors critical to this debate, including 1) Geological aspects of the Paleolake Otero Basin and the trackway site; 2) How the Ruppia cirrhosa seeds came to be found at the site; 3) The impact of the hard water effect on the radiocarbon ages attributed to the tracks; and 4) The role of stable carbon isotopes in evaluating the accuracy of Ruppia radiocarbon dates. Our research demonstrates that these contextual factors have largely been ignored by the NPS researchers, to the point that their Last Glacial Maximum (LGM) claims for the ages of the human footprints are likely erroneous. Dr. Robert Dello-Russo is the retired Director of the Office of Contract Archeology at the University of New Mexico. Prior to that, he was the Deputy Director at the NM Office of Archaeological Studies and the Compliance Archaeologist for the NM Department of Game & Fish—both in Santa Fe—and the owner and principal of Escondida Research Group, a private archaeological consulting firm. He has almost 40 years of archaeological experience, including field work in the Rocky Mountains, the Pacific Northwest, the Intermountain West, and the Southwest, where he served as Principal Investigator for dozens of grants funded and large scale CRM projects (including at White Sands National Park). In addition, he was the Principal Investigator for 20 years at the Water Canyon Paleoindian site in west-central New Mexico. His fields of research include hunter-gatherer prehistory in western North America, paleoclimate and paleoenvironmental studies, geomorphological processes, and the XRF sourcing of silicified rhyolites and dacites. Dr. Dello-Russo has a PhD in Anthropology/Archaeology from the University of New Mexico. Presented to the Pacific Coast Archaeological Society (PCAS) on June 12, 2025. For additional information on the Pacific Coast Archaeological Society, see the PCAS website at www.pcas.org