Gypsum Cave in eastern Clark County, Nevada, is a limestone cave and archaeological site about fifteen miles east of Las Vegas, known for important excavations in nineteen thirty and nineteen thirty-one by Mark Raymond Harrington. Evidence indicates human use by around three thousand B.C., while far older finds revealed Ice Age animals, including a Shasta ground sloth discovered by Bertha Parker in Room 3. Sloth remains dated to eleven thousand B.C. and earlier, along with preserved plant evidence, point to a cooler, wetter ancient climate. Later research also reclassified a horse skull from the cave as an extinct stilt-legged horse from around thirteen thousand B.C. The site also holds strong cultural importance for Native tribes.