Nova: Ice Age Ghost Tracks

Thousands of prehistoric footprints left by Ice Age humans and animals stretch for miles across the blinding white surfaces of New Mexico's White Sands National Park. The phenomenal collection of prints preserves a unique series of snapshots of life and behavior, capturing moments when humans crossed paths with extinct Ice Age beasts, including enormous ground sloths and mammoths. Producer: Laurie Cahalane, Bella Falk. Narrator: Kirk Johnson