`MAN IS A GEOLOGIC AGENT'

The ancient riverbed beneath us evidently passed through Gold Run, picked up a fossil tributary coming in through Dutch Flat, and went off to the northwest via Red Dog and You Bet. Before human beings appeared on earth, glacial ice and modern streams and other geologic agents had obliterated large parts of the Eocene river system. People had come near eliminating the rest. "Man is a geologic agent," Moores said, with a glance that swept the centennial valleys.