The American West of the 1930s and 1940s was still a place of prospectors, cowboys, ranchers, and mountaineers, one that demanded backbreaking, lonely, and dangerous work. Still, mid-century pioneers such as David Lavender remembered “not the cold and the cruel fatigue, but rather the multitude of tiny things which in their sum make up the elemental poetry of rock and ice and snow.” And as the nation exhausted its gold and silver veins, as law...