These are Bywell and Croftshaw soils. Bywell soils have more than 35 percent rock fragments. Croftshaw soils have less than 35 percent clay. Crubas soils are used for livestock grazing and wildlife habitat. The present vegetation is bluegrass, sedges, rushes, alpine timothy, shrubby cinquefoil, clover and tufted hairgrass.
Series is of small extent.
Rio Arriba County, New Mexico, 1989. The series name is coined.