These soils are formed in fine-textured lacustrine sediments which occupy low-relief basins in southwestern Idaho. Soils in these basins are subject to brief ponding following intense rainfall; they are ponded for less than 45 consecutive days in most years, mainly in the spring. This area presently has a dry climate, receiving about 15" of annual precipitation; however, during a wetter period in the past these basins contained lakes and were depositional areas for silty sediments. These lands are used primarily for rangeland and have a native vegetative community of silver sagebrush, Idaho fescue, and alkali bluegrass.