Definition of alluvial fan in US English:

alluvial fan


  • A fan-shaped mass of alluvium deposited as the flow of a river decreases in velocity.

    • ‘Increasing soil instability, however, has failed to prevent squatters from colonising precarious perches on the hillsides, on the slopes of alluvial fans, or in the mouths of regularly flooded canyons.’
    • ‘The Copper River alluvial fan is an outwash plain, that is, formed from sediments deposited by glacial meltwater.’
    • ‘The topographic expression of these gravels suggests they represent uplifted and dissected alluvial fans that accumulated along the foot of the Western Ranges.’
    • ‘Water-transported sediments formed alluvial fan deposits that were laid down on essentially flat-lying volcanic flows by streams flowing toward the center of the rift basin.’
    • ‘Deposits in the Solund Basin consist almost entirely of alluvial fan conglomerates.’