Alluvial Fan: A large, fan-shaped pile of sediment -- unconsolidated gravel, sand, silt and clay -- forming at the base of narrow canyons onto a flat plain at the foot of a mountain range.
Arroyo: A dry desert gully, usually a small, narrow canyon with steep walls and flat, gravel strewn floor.
Bajada: A broad, sloping depositional surface at the base of a mountain range caused by the coalescing of alluvial fans.
Blowout: A depression in the land surface caused by wind erosion.
Butte: A narrow, flat-topped hill of resistant rock with very steep sides. Probably formerly a mesa.
Desert Pavement: A thin, surface layer of closely packed pebbles.
Desert Varnish: A hard, dark, shiny coating on rocks caused by chemical/biological action.
Dunes: Mounds of loose sand grains shaped by the wind.
Flash Flood: Sudden local flood of high discharge and short duration.
Hoodoo: A bizarre-shaped column or pillar caused by differential erosion on rocks of different hardness.
Loess: Deposit of wind-blow silt and clay in angular grains and weakly cemented by calcite.
Mesa: A large, broad, flat-topped hill bounded by cliffs and capped with a resistant rock layer.
Mudflow: In the desert, usually flash flood laden with enough sediment to become plastic.
Pediment: A gently sloping surface cut into the solid rock of a mountain, covered with a thin layer of gravel. Occurs uphill of a bajada, which is completely depositional.
Playa: A very flat, dry lakebed of hard, mud-cracked clay.
Ventifacts: Rocks with flat, abraded surfaces caused by wind-blown sand.
