While illustrating for the benefit of a small group on a field trip, the collapse of Mt. Mazama occurred to the satisfaction of all concerned, including the naturalist. The peak had been reconstructed with a pile of loose earth beside the trail. A stick was pushed into the summit of the pile, to produce a crater. This stick passed without resistance into a gopher hole below the intended crater, whereupon the ancient mountain promptly fell in upon itself, leaving a caldera of the proper proportion to serve as the setting for Crater Lake.