Question

How are alluvial fans created by rivers?

• A. Erosion of landforms in the middle course of the river
• B. Deposition of heavier sediments due to gentler slopes
• C. Erosion of outer banks of a river to form a loop
• D. Collapsing of hard rocks due to the pressure of a waterfall

Answer 1

The correct option is B Deposition of heavier sediments due to gentler slopes

The river flows down from a hill carrying sediments. However, in the foothills, as slopes become gentle, the load of sediments becomes too heavy to be carried by the river over gentler slopes. Thus, sediments get deposited near the foothills, forming a triangular shape - resembling a manual fan or a hand fan, and this is how alluvial fans are created.