Alluvial Fan
Alluvial Fan
(3) (Montane) A semiconical, or fan-shaped constructional, major landform that is built of more-or-less stratified alluvium with or without debris flow deposits, that occurs on the upper margin of a piedmont slope, and that has its apex at a point source of alluvium debauching from a mountain valley into an inter-montane basis. Also, a generic term for like forms in various other landscapes.
An alluvial fan is a fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyononto a flatter plain. A convergence of neighboring alluvial fans into a single apron of deposits against a slope is called a bajada, or compound alluvial fan