A bajada is a wide apron of rock and debris that forms where many alluvial fans coalesce. 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 from the mountain front to a distance of several miles. A bajada is usually composed of gravelly alluvium and may even have large boulders interbedded in it. The slope of a bajada is usually less than 7°.