Through the Valley of the Shadow

On June 13, 1999, a rumble began high on a sheer cliff wall, like faraway thunder, at Glacier Point in Yosemite National Park. 100 tons of rock rained down on three young climbers. Peter, a college student from Colorado, turned to a long-ago climbing lesson taught to him by his father.

As a little boy first astride a mountain, he learned to always protect a partner at the end of the rope...to never let go. He was not anchored and could have easily slipped from his harness and run for cover,...