Alluvial Fans
Alluvial fans form when a confined body of flowing water carrying sediment flows into an unconfined (or less confined) area, allowing the channel to spread out and flow in many directions. As this happens, sediment is deposited, causing channels to migrate back and forth over this new surface. Eventually, the accumulation of sediment forms a wide fan-shaped deposit, kind of like a delta on dry ground rather than within another body of water.