THE GEOLOGY, PALEOHYDROLOGY AND FOSSILS OF TULE SPRINGS FOSSIL BEDS NATIONAL MONUMENT, NEVADA: A LATE PLEISTOCENE TREASURE TROVE
Investigations focused on detailed stratigraphic analysis, geologic mapping and targeted dating with the goal of establishing the context for the fauna and integrating the TSLF into a rigorous lithostratigraphic and geochronologic framework. In collaboration with the USGS, we established a highly resolved chronology based on 14C dating of charcoal and luminescence dating of sediments. We also redefined and established new geologic units within the informally named Las Vegas Formation. Our results show that ground-water discharge deposits in the region record dramatic hydrologic changes in response to abrupt climate oscillations during the late Pleistocene, including the repeated growth and collapse of entire wetland systems. The hydrologic response of the Las Vegas paleowetlands demonstrates a tight correlation with Greenland/North Atlantic climate proxy data on a sub-millennial scale. This is the first record to demonstrate millennial and sub-millennial scale climate oscillations in groundwater discharge deposits, which are fairly common through the southwestern U.S.
The newly established Tule Springs Fossil Beds National Monument therefore preserves these linchpin deposits and their attendant fauna in the upper Las Vegas Wash for posterity, and our scientific results provide a powerful interpretive springboard for the new monument.