bajada

bajada, broad slope of debris spread along the lower slopes of mountains by descending streams, usually found in arid or semiarid climates; the term was adopted because of its use in the U.S. Southwest. A bajada is often formed by the coalescing of several alluvial fans. Such coalescent fans are often mistaken for erosional landforms known as pediments. The repeated shifting of a debouching stream from one side of a fan to the other spreads the sediment widely and almost uniformly. As the sediment eventually grows together, the slope may extend outward from the mountain front to a distance of several kilometres. A bajada is usually composed of gravelly alluvium and may even have large boulders interbedded in it. The slope is usually less than 7°. In humid climates, landforms of this nature are usually referred to as piedmonts.