Aiken's Wash in eastern California's Mojave National Preserve is significant for both archaeology and geology. Its one thousand four hundred fifty-acre historic district contains major late pre-Columbian rock art sites, notable in the Mojave Desert for combining pictographs and petroglyphs. Large concentrations appear at Aiken's Arch and Milky Way Caves, with additional groupings at nearby named sites. The imagery includes human-like figures, circles, curved forms, grids, lattice patterns, and occasional animal or plant forms, while evidence of habitation includes rockshelters and a house site with multiple round house rings. The wash also preserves extinct cinder cones and lava flows from multiple volcanic periods, with activity possibly as recent as eight hundred to one thousand years ago.