How would you describe an alluvial fan?
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.
What is alluvial fan used for?
Alluvial fans border the mountain fronts with the apex of each fan just within a canyon mouth that serves as the outlet for a mountain drainage system. Sediment from erosion within the mountains is moved by these drainage systems to the adjacent basin.
What are some famous alluvial fan?
Famous Alluvial Fans:
Death Valley National Park, California, USA. Planet Mars. Taklimakan Dessert, Xin Jiang, China. Zagros Mountains, Iran.
What are the possible hazards associated with alluvial fans?
The main hazards affecting alluvial fans include inundation by flood water, debris flow and debris flood deposits, channel migration, deposition, and erosion. Considerable buildup of sedimentation may result from alluvial fan floods.
What is a alluvial fan and how is it formed?
An alluvial fan is a fan-shaped area where silt, sand, gravel, boulders, and woody debris are deposited by rivers and streams over a long period of time. Alluvial fans are created as flowing water interacts with mountains, hills, or steep canyon walls.
How do alluvial fans change?
Alluvial fans are formed when water and sediments pass through a narrow gap between hills, mountains or canyon walls and then slows down and spread out when it reaches an open plain. The top of the triangle of an alluvial fan is commonly called the apex and the wide part at the bottom is called the apron.
Where is the largest alluvial fan?
Originating between the Kunlun and Altun mountain ranges of the Taklimakan desert directly south of Ao Yiyayi Lakexiang, Qarqan, Bayingol, XinJiang, China, the largest alluvial fan in the world spans the desert: 56.6 kilometers wide and 61.3 kilometers long.
Where is the most likely place to find an alluvial fan?
Alluvial fans 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. They have also been found on other bodies of the Solar System.
What is the difference between a Delta and an alluvial fan?
Alluvial fan and delta are landforms that form from the deposition of sediment materials. The main difference between alluvial fan and delta is that alluvial fans form from the deposition of water-transported materials whereas delta form from the deposition of sediment carried by rivers at an estuary.
Are alluvial fans deposition or erosion?
Alluvial fans typically form where flow emerges from a confined channel and is free to spread out and infiltrate the surface. This reduces the carrying capacity of the flow and results in deposition of sediments. The flow can take the form of infrequent debris flows or one or more ephemeral or perennial streams.
Where do alluvial fans commonly form?
Alluvial fans are often found in desert areas, which are subjected to periodic flash floods from nearby thunderstorms in local hills. The typical watercourse in an arid climate has a large, funnel-shaped basin at the top, leading to a narrow defile, which opens out into an alluvial fan at the bottom.
When was the alluvial fan formed?
July 15, 1982
The Alluvial Fan is a fan-shaped area of disturbance in Rocky Mountain National Park. It was created on July 15, 1982, when the earthen Lawn Lake Dam above the area gave way, flooding the Park and nearby town of Estes Park with more than 200 million gallons of water.
How old are alluvial fans?
Many alluvial fans had a period of major formation between approximately 2,500 and 9,000 years ago. Geologically, these fans are known as the Corrington Member of the DeForest Formation. These are usually low angle fans found in medium to large size valleys.
What is the difference between a delta and an alluvial fan?
How are alluvial fans formed?
How is an alluvial fan created?
Are alluvial fans rare?
If the water can pond, the fine grains settle out and the water evaporates forming minerals like gypsum and halite, and creating playa lake deposits. Deposition on a given alluvial fan is very rare – one event occurs about every 300 years on most fans in the southwestern US.