1. Bouguer and isostatic residual gravity maps of the Colorado River Region, including the Kingman, Needles, Salton Sea, and El Centro quadrangles [cartographic material] Yale Public content 1986. 2023-10-26T19:57:25Z. 2023-10-27T03:02:28Z. Geological Survey (U.S.). The Survey. English. cartographic image. Public. Colorado River Region (Colo.-Mexico), North America, and Colorado River Region.