Approximately 350 acres of alluvial valley soils in southern California are being lost to urbanization each day according to estimates by the University of California Agricultural Extension Service. Whether or not this loss of the better agricultural lands continues at the same rate, it is a fact that less desirable upland soils are already being developed for citrus as well as for other crops. Much of the area being planted in Riverside and San Diego counties includes rolling soils underlain at various depths by bedrock. The type of topography characteristic of these upland areas is shown in the photos.

Assistance and cooperation in this study were received from James Cleveland, Bert Westover, Topham and Sons—and the Soil Conservation Service, and Agricultural Research Service, USDA.