An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but are also found in more humid environments subject to intense rainfall and in areas of modern glaciation.

alluvial fan, unconsolidated sedimentary deposit that accumulates at the mouth of a mountain canyon because of a diminution or cessation of sediment transport by the issuing stream.

2023年10月19日 · An alluvial fan is a triangle-shaped deposit of gravel, sand, and even smaller pieces of sediment, such as silt. This sediment is called alluvium . Alluvial fans are usually created as flowing water interacts with mountains , hills , or the steep walls of canyons .

2020年8月23日 · Alluvial fans form in areas with a steep gradient from a drainage catchment to the basin floor. Tectonic activity is typically required to maintain steep slopes because they erode to lower slopes through time.

2024年10月15日 · Alluvial fans are characterized by their triangular or fan-like shape, with the apex of the fan located at the point where the mountain valley or canyon opens onto the plain. The fan itself is composed of a variety of sediments, including gravel, sand, silt, and clay, which have been eroded from the surrounding mountains and transported ...

Alluvial fans are mounds of coarse grained sediments formed when a confined stream disgorges into an unconfined area. They typically occur along the margins of mountain ranges where bedrock incised channels draining uplands spill out on to broad open valley floors.

Alluvial fans occur where confined mountain streams open up into valleys or onto plains (Figure 3). They are widespread in dryland environments, but also occur in subtropical, temperate, and even arctic and subarctic zones (Oguchi et al., 2001; Harvey et al., 2005).

Alluvial and fluvial fans are the most widespread depositional landforms bordering the margins of long-lived highland regions and actively subsiding continental basins, across a broad spectrum of tectonic and climatic settings.

2024年10月25日 · Alluvial fans form through a combination of fluvial and gravitational processes, as sediment-laden water flows from a steep slope or mountain front onto a more gently sloping surface. As the water flows away from the mountain front, it loses energy and deposits its sediment load, forming a fan-shaped deposit of gravel, sand, and silt. ...

6 天之前 · Alluvial fan lobes encroaching a gypsum-halite salar, Altiplano, northern Chile. The elevated fan (left of the access trail) records deposition during a phase of higher lake-salar levels; the older fan is now partly degraded. The cuspate and indented distal fan margin record a succession of fan lobes interfingering with the saline gypsum-halite ...