Slump in loose sand down slipface of dune, White Sands National Monument. They are among the most numerous and dangerous types of landslides in the desert. Material on steep slopes that becomes saturated with water after prolonged, intense rain or rapid snow melt may develop a debris flow or mud flow. The resulting slurry of rock and mud may destroy homes, wash out roads and bridges, sweep away cars, knock down trees, and obstruct streams and roadways with thick deposits of mud and rocks. Debris-laden flows are sometimes distinguished from mudflows that are soupier in consistency and carry less rock.
Debris flow on trail, Grand Canyon.
Mt. St. Helens eruption. Sheetwash is a thin sheet of water flowing across the surface as a result of an intense rainstorm. Although the water flows as a thin sheet, it is capable of transporting pebbles, sand, and mud. Sheetwash takes place during intense storms and after sustained hard rains have saturated the soil. Vegetation and cryptobiotic crusts have a very important role in retarding sheetflow by binding together surface materials, inhibiting erosion and improving absorption of water.