Valley Walls

Half a century ago a rag-tag group of innovators was building a foundation for modern American rock climbing from a makeshift home base in Yosemite. Photographer Glen Denny was a key figure in this golden age of climbing, capturing pioneering feats on camera while tackling challenging ascents himself.

In entertaining short pieces enlivened by his iconic black-and-white images of Yosemite''s big wal...