A wide sloping deposit of sediment formed where a stream leaves a mountain range is called an alluvial fan. An alluvial fan is the deposition of sediment on a landform like mountain. It forms as an open fan or cone of sediment. The sediments are left by natural drainage system like river on the landform.
There are two types of alluvial fans.
1. Debris dominated: These includes viscous mixture of water, mud, gravel along with woody debris. This transfer large boulders of landform soil.
2. Floodwater dominated: Water will spill in the alluvial fan in the form of thin sheets. This can transfer fine particles of landform soil.
