Rocks with a profile

The Joshua Tree National Park outcrops are mainly made of granitoids in the size from isolated groups of boulders to entire mountains. The granitois, mostly having monzogranite to granodiorite composition, are cutted by a set of parallel fractures. Erosion plays a major role in sculpting the Joshua Tree landscape, removing unconsolidated material starting from into the fractures, leaving the boulders standing alone in the desert.