Bert Loper, the Grand Old Man of the Colorado, was born the day Major Powell discovered the confluence of the San Juan and Colorado in 1869. He died just days after the first motorboat had passed through Grand Canyon. He knew every river runner in between, and by the time of his death at 80 years old, had run more of the Colorado than anyone. But it was never easy--orphaned an abused, Loper had to make his way along the bottom of society, often as...