Extent of ice sheets during the Last Glacial Maximum (LGM) at the time the White Sands prints were made. At that time, global sea level was over 400 feet lower than it is today. Glaciers covered around 8% of Earth's surface and 25% of Earth's land area. During the LGM, pathways to the Americas across Beringia from Asia were blocked, suggesting that the people who lived at Lake Otero arrived in North America centuries or even millennia prior to the formation of the ice sheets. Some theories hold that people came from Asia along the ice-free coast, tracing the edges of the mile high ice. Image courtesy the National Park Service.