alluvial fan
- noun
- /əˈluːviəl fæn/
- Specialized
- Geologists study the structure of the alluvial fan to understand how sediment is deposited over time in mountainous regions.
Examples
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Farmers often choose to cultivate their fields on an alluvial fan because the soil is more fertile due to the sediment deposited by the flowing water.
-
The Okavango Delta (figure 1) is one of the largest inland alluvial fans in the world (McCarthy and Ellery 1994).
Academic text (2009) -
Alluvial fans would have been ideal sites for growing crops during the dry season because they often have more soil moisture.
Academic text (2002) -
A large pagoda forest grew along the base of the rugged alluvial fan.
Fiction book (2001) -
The imagery shows an alluvial fan of material washed down from the rim, streaked by many apparent channels, sitting uphill of the new finds.
Blog text (30) -
Alluvial fans are always younger than the material beneath them, always younger than bedrock slopes along their flanks.
Academic text (1998) -
The Okavango Delta, Botswana, a giant oasis in the Kalahari Desert of southern Africa, is an immense alluvial fan created by the rivers that drain the highlands of Angola.
Academic text (2009) -
The river created an alluvial fan as it spread out at the base of the mountain, depositing rich sediment for the surrounding land.
Synonyms
A wide fan of sand and stones that forms when a fast river slows at a mountain base
How Wide
- Specialized
- Specialized
- Specialized
Surface Forms
Morphology
The meaning is directly derivable from combining 'alluvial' (river-deposited sediment) with 'fan' (fan-shaped arrangement): a fan-shaped accumulation of sediment is the straightforward composition. This noun-noun/adj+noun compounding is cross-linguistically common and follows transparent semantic composition, so a learner who knows the constituents would understand it.
Etymology
Alluvial fan comes from a simple picture: alluvial means soil and stones carried by water, and fan shows the wide, 'fan-shaped' spread that appears when a fast mountain stream slows and spreads out. So the name tells us it is a wide, fan-shaped pile of river material at the mountain's base.