These two units are different from the other map units because they are actually subunits of the larger Stagecoach soil series. They are distinctive and widespread enough that they make up a substantial portion of the watershed and are therefore designated as a single map unit here. Because they mostly contain rock material, they are designated by the dominant rock type present within the unit. Neither units stores water well and runoff is high in both. They typically occur at elevations around 3,200 ft. ( 976m).
Stony rough land, sandstone: This subunit consists of steep and very steep hillsides and canyon walls on which there are shallow, cobbly and stony soils and outcrops of sandstone and basalt. It occurs in areas where the average annual precipitation is 18-20 inches. In most places, the soil material is less than 8 inches deep and the slope ranges from 20 to 60 percent. These areas are highly erodible, with protective plant cover consisting of oak brush, some juniper, and moderate stands of blue grama.
Stony steep land, basalt: This subunit consists of basalt outcrops, small broken basalt escarpments, and pockets of very shallow and shallow, brown, clayey soils that have stones, cobblestones, and gravel on the surface. It occurs in areas with moderate to steep side slopes and on the walls of canyons in the central and western parts of the watershed, where the average annual precipitation is 13-16 inches. Plant cover consists of turbinella oak, juniper, loco, pricklypear, and sideoats grama. The surface is covered in basalt talus, stones, and cobblestones in areas where it is devoid of vegetation.
Williams, J.A.; Anderson, T.C., Jr. 1967. Soil Survey of Beaver Creek Area, Arizona. USDA Forest Service, Soil Conservation Service and Arizona Agriculture Experiment Station.