The map area is comprised entirely of late Cenozoic sediments. The map area can be divided into two geomorphic settings. The NW half of the quadrangle includes Yuma Valley and consists of Holocene Colorado River deposits. Approximately 12m (40 feet) above the river valley is Yuma Mesa which occupies the SE half of the quadrangle and is composed of late Pleistocene Colorado River sediments called the Chemehuevi Formation.