DISASTERS: Death on the Madison

In the high Montana country west of Yellowstone Park, a full moon, shining on the pine-covered mountains, etched the thin, black notch of canyon where the trout-filled Madison River winds away from Hebgen Lake. Near the canyon mouth, seven miles below the Montana Power Co.'s 87-ft.-high dam, Purley R. Bennett, a Coeur d'Alene, Idaho truck driver, and his wife Irene had gone to sleep in their trailer. Outside, their three sons and daughter were rolled up in sleeping bags on the ground. At 11:30 p.m. an "indescribable" roar woke them all. What followed would never be forgotten—by those...