The soils formed in residuum and colluvium from andesite and rhyolite. Slopes are 30 to 75 percent. Elevations are 4,800 to 7,300 feet. The climate semi-arid with cool, moist winters and hot, dry summers. These are the Calpeak and Gabbvally soils.
Calpeak soils are shallow to a paralithic contact.
Gabbvally soils have an argillic horizon. The native vegetation is Wyoming big sagebrush, Sandberg bluegrass, green ephedra and bottlebrush squirreltail. These soils are not extensive. Xeric feature - has an Aridic soil moisture regime that borders on Xeric.