Alluvial fan depositions from "summary" of Fundamentals of Geomorphology by Richard Huggett,Emma Shuttleworth
An alluvial fan is a feature of the landscape created by the accumulation of sediment and other materials from water runoff. They are typically formed in mountainous regions and their deposits are often visible in the form of a cone or fan-shaped sediment pile.- Alluvial fans are landforms with fan-like characteristics, formed by deposits of sediment nature where streams join in a broader area. They can be seen close to mountain fronts throughout the world and clues us in on how fluvial erosion affects the environment.
- Geomorphologists point out that in order to understand current landscape condition which contains alluvial fan deposit geological analysis is necessary. Evidence from external sources such as rocks, stones, minerals etc can help elucidate the origin of alluvial fans.
- Alluvial fans are dynamic natural environments exhibiting diverse characteristics depending on the forces driving its formation and evolution. Amount of runoff, underlying geological structure and slope gradient play a major role in specifying the shape and size of alluvial fan channels.
- Studies reveal that big sizes of sediment depositions have been observed frequently in sculpting out alluvial fans landforms. This suggests deposition is an integral part of landscape development and needs to be well understood.
- When a channel reaches its lower end it increases sharply in size causing sediment sediment particles that have been carried along in the stream suddenly become deposited. The ability of alluvial fans to self-channelize as river networks give rise to their distinct features.
- Over time, these sediments get build up occupying higher topographical positions since they occupy flatter areas; they usually fill up ridges and beyond leaving highlands untouched.
- Alluvial fans have also gone through continual spatial variations affected naturally or due to human activities. Therefore studied over long periods of time, they can provide useful insights concerning general geomorphic trends and preservation of soil moisture during floods.
- These features contribute different amounts of material every time contributing into creating new variety of fan types and features like roll waves which helps in understanding volume, intensity and kind of sedimentation.
