Gypsum Cave is a five-room limestone cave in Sunrise Mountain, approximately 12 miles east of Las Vegas. For a twelve-month period, between January 1930 and 1931, noted early archaeologist Mark R. Harrington (1882-1971) and a small crew of Native Americans dug through most of the cave's deposit. Harrington was interested in the cave for its potential to provide evidence of a period in the distant past when it was occupied by both humans and now-extinct mammals, especially the ground sloth (Nothrotheriops shastense).