Riverside County was formed from parts of San Diego and San Bernardino Counties in 1893. Some of the first orange groves in California came from here as well as some early California wine. Geographically, the county is quite diverse. The county is mostly mountainous with broad valleys separating the ranges. The largest of those valleys, the Coachella Valley, is also a part of a rift zone where the North American continent is being pulled apart. Rivers flow at both the eastern and western ends of the county. To the west is the Santa Ana River, a mostly wide sandy stream in contrast to the Colorado River on the east end, a wide river that provides a large amount of the drinking water in the county.