S7, E2: Strange rock carvings from 8,000 BC, unexplained sightings in the New World, and a frightening anomaly plaguing the American West. Is there more to America's past than is found in our history books?

S7, E2: Strange rock carvings from 8,000 BC, unexplained sightings in the New World, and a frightening anomaly plaguing the American West. Is there more to America's past than is found in our history books?