A USGS FACT SHEET: FOSSIL FOOTPRINTS AND ICE AGE ECOSYSTEMS OF WHITE SANDS NATIONAL PARK

U.S. Geological Survey (USGS) Fact Sheets are condensed format publications, written in plain language with eye-catching graphics, that provide for rapid publication and dissemination of facts and findings on a wide variety of topics to the public. In collaboration with the National Park Service, they are also developed as companion educational tools to disseminate scientific research conducted in national parks. A draft USGS Fact Sheet on the ancient human footprints and megafaunal tracks at White Sands National Park is one such publication. It begins by setting the stage during the Pleistocene, when the Tularosa basin in south-central New Mexico was occupied by pluvial lake Otero. Subsequent deflationary processes exhumed the lake sediments, creating the world’s largest gypsum sand dunes and revealing the most geographically extensive and highest density of fossilized megafaunal trackways and human footprints in North America, possibly the world. The Fact Sheet highlights studies at White Sands of previously undocumented human and megafaunal interactions and also focuses on the critical contextual and chronologic information surrounding the human footprints and the implications regarding the peopling of the Americas. The publication includes evidence from ground penetrating radar imagery and excavated surfaces in White Sands National Park that reveal multiple in situ human footprints are stratigraphically constrained and bracketed by seed layers that yielded calibrated radiocarbon ages between ~23 and 21 thousand years ago. New research with independent chronologic techniques has recently confirmed the accuracy of these ages. This timing coincided with a Northern Hemispheric abrupt warming event, Dansgaard-Oeschger event 2, which drew down lake levels and allowed humans and megafauna to walk on newly exposed surfaces, creating tracks that became preserved in the geologic record. The findings at White Sands confirm the presence of humans in North America during the Last Glacial Maximum, adding evidence to the antiquity of human colonization of the Americas and providing a temporal range extension for the coexistence of early inhabitants and Pleistocene megafauna. The USGS Fact Sheet of the White Sands research serves to enhance the visitor experience, communicate the science, brining the public into the story in an engaging and information rich manner.