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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.
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]
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]
A diagram of various depositional environments. In geology, depositional environment or sedimentary environment describes the combination of physical, chemical, and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be formed after lithification, if the sediment is preserved in the rock record.
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 .
A desert pavement, also called reg (in western Sahara), serir (in eastern Sahara), gibber (in Australia), or saï (in central Asia) [1] is a desert surface covered with closely packed, interlocking angular or rounded rock fragments of pebble and cobble size. They typically top alluvial fans. [2] Desert varnish collects on the exposed surface ...
The Virgin River carved out 1,300 feet (400 m) of sediment in about 1 million years. [a] [27] This is a very high rate of downcutting, about the same rate as occurred in Grand Canyon during its most rapid period of erosion. [27] About 1 million years ago, Zion Canyon was only about half as deep as it is today in the vicinity of Zion Lodge. [26]