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Alluvial fans are common in the geologic record, such as in the Triassic basins of eastern North America and the New Red Sandstone of south Devon. Such fan deposits likely contain the largest accumulations of gravel in the geologic record. Alluvial fans have also been found on Mars and Titan, showing that fluvial processes have occurred on ...
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.
The thickness of alluvial fans forming due to basin margins are influenced tectonically. [3] If the alluvial fan gets thicker and the grains become more coarse heading up the fan, this indicates that the basin margin is tectonically active and the building of the alluvial fan being more active than the deposition rate.
Alluvial – Loose soil or sediment that is eroded and redeposited in a non-marine setting – type of Fluvial deposit. Caused by moving water in a fan shape (Alluvial Fan) and containing mostly impermeable and nonporous sediments well sorted. Aeolian – Processes due to wind activity. Often in deserts and coastal regions and well sorted ...
The present consensus is that "alluvium" refers to loose sediments of all types deposited by running water in floodplains or in alluvial fans or related landforms. [1] [7] [8] However, the meaning of the term has varied considerably since it was first defined in the French dictionary of Antoine Furetière, posthumously published in 1690.
Matrix-supported conglomerates, as a result of debris-flow deposition, are quite commonly associated with many alluvial fans. When such conglomerates accumulate within an alluvial fan, in rapidly eroding (e.g., desert) environments, the resulting rock unit is often called a fanglomerate. [9]
In this arid environment, alluvial fans form at the mouth of these streams. Very large alluvial fans merged to form continuous alluvial slopes called bajadas along the Panamint Range. [33] The faster uplift along the Black Mountains formed much smaller alluvial fans because older fans are buried under playa sediments before they can grow too large.
Typical aggradational environments include lowland alluvial rivers, river deltas, and alluvial fans. Aggradational environments are often undergoing slow subsidence which balances the increase in land surface elevation due to aggradation.