Goblin Valley State Park in Utah's San Rafael Desert is renowned for one of the world's largest concentrations of hoodoos, dense fields of mushroom-shaped sandstone pinnacles formed by erosion in Jurassic Entrada sandstone laid down about 170 million years ago. Native peoples long used the surrounding landscape, with Fremont, Paiute, and Ute traces surviving elsewhere in the Swell. The secluded basin gained wider notice in the late 1920s when Arthur Chaffin reached a viewpoint above it, and he later helped publicize it through photographs after returning in 1949. Utah established the area as a state park in 1964, preserving its unusual geology, desert life, and fragile formations.