alluvial fan
noun Physical Geography.
a fan-shaped alluvial deposit formed by a stream where its velocity is abruptly decreased, as at the mouth of a ravine or at the foot of a mountain.
Also called
alluvial cone.
Origin of alluvial fan
First recorded in 1870–75
Words nearby alluvial fan
allurement,
alluring,
allusion,
allusive,
alluvial,
alluvial fan,
alluvial mining,
alluvial plain,
alluvion,
alluvium,
ally
British Dictionary definitions for alluvial fan
alluvial fan
alluvial cone
noun
a fan-shaped accumulation of silt, sand, gravel, and boulders deposited by fast-flowing mountain rivers when they reach flatter land
Scientific definitions for alluvial fan
alluvial fan
[ ə-lōō′vē-əl ]
A fan-shaped mass of sediment, especially silt, sand, gravel, and boulders, deposited by a river when its flow is suddenly slowed. Alluvial fans typically form where a river pours out from a steep valley through mountains onto a flat plain. Unlike deltas, they are not deposited into a body of standing water.