Slopes are 2 to 15 percent. Elevations are 5,000 to 6,300 feet. The mean annual precipitation ranges from 10 to 14 inches with about half falling as snow and rain in April, May, and early June. The frost-free season is estimated to range from 100 to 130 days depending upon elevation, aspect, and air drainage. These are the Gystrum , Rekop , and Spearfish soils and the competing Threetop series.
Gystrum soils have gypsic mineralogy and a cambic horizon.
Rekop and Spearfish have bedrock at less than 20 inches and have no diagnostic subsurface horizons. Native vegetation consists of western wheatgrass, needleandthread, blue grama, green needlegrass, and smooth phlox. North central and central Wyoming. The series is of moderate extent.