Pinkham soils are on moderately to steeply sloping alluvial fans, glacial moraines, till plains, and mountain side slopes. Slopes typically range from 4 percent to about 60 percent or more. These soils formed in thick, noncalcareous, alluvial fan materials derived from gneiss, schist, and quartzite. At the type location the average annual precipitation is 18 inches with peak periods of precipitation in the spring and early summer months. These are the competing Darling soils and the MacFarlane soils.
MacFarlane soils have argillic horizons.
They are used as native pastureland, for forestry, and for recreation. Native vegetation is spruce, fir, and a weak understory of shrubs and grass. Mountain areas of Colorado. The series is of moderate extent. Jackson County, Colorado, 1973.