When the six Boy Scouts from suburban Maplewood, N.J., went camping in the Grand Canyon, they expected an adventure they would long talk about, but they did not expect to be clinging to treetops and praying to survive a flash flood. The six Scouts and three adult leaders were eventually guided to safety by American Indians who live in the area, and plucked out of the wilderness by a Black Hawk helicopter. By the time they flew away, the 10-yard-wide canyon next to a stream where they had been camping had become a 300-yard-wide raging river. The scouts and their...