Mammoth Hot Springs, Pulpit Terraces, Yellowstone National Park, circa 1892

Yellowstone National Park, established 1872, was America's first national park. The scenery that early explorers, surveyors, artists, and photographers encountered at Mammoth Hot Springs was among the most striking in the park. The hot springs that created the terraces, like this terrace the explorers named "Pulpit", were constantly moving and shifting--leaving old terraces dormant and forming new ones.