fan
Quick Summary
An alluvial fan is a geological feature formed by the deposition of sediment carried by a stream as it emerges from a narrow canyon onto a broader plain. These deposits are typically fan-shaped, with the apex at the canyon mouth and the base extending outwards.12
Alluvial fans are commonly found in arid and semiarid regions, where seasonal rainfall or snowmelt can cause flash floods that transport sediment. The material deposited ranges from coarse gravel near the apex to finer sands and silts towards the base. These features are economically important as they can serve as significant groundwater sources for irrigation and life support, and some cities, like Los Angeles, are built on them.134
A "rock fan" is a similar fan-shaped bedrock surface at the foot of a mountain, which may be covered by a thin layer of alluvium and can be mistaken for an alluvial fan. A "fan delta" is an alluvial fan that merges with a river delta.56
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riverAlluvial fansAlluvial fans are depositional features formed at one end of an erosional-depositional system in which sediment is transferred from one part of a watershed to another. Erosion is dominant in the upper part of the watershed, and deposition occurs at its lower reaches where sediment is…
Read MoreAlluvial fans are depositional features formed at one end of an erosional-depositional system in which sediment is transferred from one part of a watershed to another. Erosion is dominant in the upper part of the watershed, and deposition occurs at its lower reaches where sediment is…
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Transfer of sediment from source basins to depositional sites on a fan surface involves flow consisting of several types, ranging from high-viscosity debris or mudflows to flows involving normal water. The type of flow experienced on any fan depends primarily…
Read MoreTransfer of sediment from source basins to depositional sites on a fan surface involves flow consisting of several types, ranging from high-viscosity debris or mudflows to flows involving normal water. The type of flow experienced on any fan depends primarily…
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