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Alluvial fans in Holden crater have toe-trimmed profiles attributed to fluvial erosion. [11] The few alluvial fans associated with tectonic processes include those at Coprates Chasma and Juventae Chasma, which are part of the Valles Marineris canyon system. These provide evidence of the existence and nature of faulting in this region of Mars.
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.
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".
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]
Areas where more particles are dropped are called alluvial or flood plains, and the dropped particles are called alluvium. Even small streams make alluvial deposits, but it is in floodplains and deltas of large rivers that large, geologically-significant alluvial deposits are found. The amount of matter carried by a large river is enormous.
Processes of vesicular horizon development and desert pavement formation on basalt flows of the Cima Volcanic Field and alluvial fans of the Avawatz Mountains Piedmont, Mojave Desert, California. Doctoral thesis, University of California, Riverside. Goudie, A.S. 2008. The history and nature of wind erosion in deserts. Annual Review of Earth and ...
Aggradation (or alluviation) is the term used in geology for the increase in land elevation, typically in a river system, due to the deposition of sediment. Aggradation occurs in areas in which the supply of sediment is greater than the amount of material that the system is able to transport .
Debris flows are accelerated downhill by gravity and tend to follow steep mountain channels that debouche onto alluvial fans or floodplains. The front, or 'head' of a debris-flow surge often contains an abundance of coarse material such as boulders and logs that impart a great deal of friction.