The purpose of Placerita Canyon State Park, in Los Angeles County, is to preserve and protect the site of the first discovery of gold in California, in 1842. Designated as a State Historic Landmark, the unit is situated in the transition zone between the San Gabrial Mountains and the Mojave Desert, and contains sandstone formations, seasonal streams and riparian oak woodlands, as well as stands of cottonwood and native sycamore trees. The unit's location provides significant linkages connecting the Angeles National Forest, the Santa Susana Mountains, the Simi Hills and the Santa Monica Mountains. The unit contains the remnants of an historic ranch.