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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.
They make up significant percentages of many alluvial fans and debris cones along steep mountain fronts. Fully exposed deposits commonly have lobate forms with boulder-rich snouts, and the lateral margins of debris-flow deposits and paths are commonly marked by the presence of boulder-rich lateral levees .
A debris cone is commonly made when rock from a high-up narrow slit or gorge falls into a flat-floored valley. Here the soil and loose materials are deposited, leaving a mound of conical shape. While an alluvial fan is formed when flowing water rushes rock and soil down a slope, debris cones come from one of several dry processes known as mass ...
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]
Straight-type channels can be found at alluvial fans. Braided rivers, which form in (tectonically active) areas that have a larger sedimentary load than the discharge of the river and a high gradient. Meandering rivers, which form a sinuous path in a usually low-gradient plain toward the end of a fluvial system.
Alluvial fans, also called inland deltas, occur at the foot of mountain ranges and mark the presence of river floods.They contain considerable groundwater reservoirs that are replenished each year by infiltration of the water from the river branches into the usually permeable underground, thus creating rich aquifers.
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]
alluvial fan A fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyon onto a flatter plain. alluvium Soil or sediments deposited by a river or other running water. amber Fossilized resin or tree sap that is appreciated for its vivid colour, usually reddish-orange to gold or yellow ...