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For example, alluvial fans in the Himalayas show older fans entrenched and overlain by younger fans. The younger fans, in turn, are cut by deep incised valleys showing two terrace levels. Dating via optically stimulated luminescence suggests a hiatus of 70,000 to 80,000 years between the old and new fans, with evidence of tectonic tilting at ...
These fan-shaped deposits form by the deposition of sediment within a stream onto flat land at the base of a mountain. [1] The usage of the term in landscape description or geomorphology derives from the Spanish word bajada , generally having the sense of "descent" or "inclination".
In (semi)arid regions, therefore, alluvial fans are often used for irrigation of agricultural crops. The fans reveal much greenery in the harsh desert-like environment. Irrigation methods in alluvial fans differ according to the hydrological regime of the river, the shape of the fan, and the natural resources available to maintain human life.
An alluvial fan could have been deposited and formed outside of a mountain range, however, thrusting of the mountain belt could cause the alluvial fan to become broken up by the new mountain forming. Thus, the alluvial fan would be split with the fan on either side of the new mountain range development and could change the steepness of the fan. [1]
A series of adjacent alluvial fans coalescing in a basin at the foot of a mountain range. Balkanization The political fragmentation of a larger region or state into multiple smaller regions or states, often implying mutual hostility or lack of cooperation between such units, as has occurred frequently in the Balkan Peninsula of southeastern ...
Dendritic happens to be the most common, occurring when the underlying stratum is stable (without faulting). Drainage systems have four primary components: drainage basin, alluvial valley, delta plain, and receiving basin. Some geomorphic examples of fluvial landforms are alluvial fans, oxbow lakes, and fluvial terraces.
For example, volcanic eruptions may lead to rivers carrying more sediment than the flow can transport: this leads to the burial of the old channel and its floodplain. In another example, the quantity of sediment entering a river channel may increase when climate becomes drier.
The waste takes the form of huge alluvial fans, formed chiefly by occasional boulder-bearing floods from the mountains. Each fan heads in a ravine at the mountain base and becomes laterally confluent with adjacent fans as it stretches several miles forward with decreasing slope and increasing fineness of material.