How is an alluvial fan formed?
A)A stream erodes down through older terraces and entrenched meanders.
B)Sediment is deposited by debris flows and streams that decrease in velocity along the mountain front.
C)A landslide blocks the stream,causing sediment to accumulate upstream.
D)A dam increases the speed of currents below the dam.

Question

Quizplus · Accepted Answer

An alluvial fan is formed by sediment being deposited by debris flows and streams that decrease in velocity along the mountain front. As the sediment-laden water flows down the steep mountain slopes, it loses velocity and deposits sediment in a fan-like shape as it spreads out onto a flatter surface. This process is repeated over time, building up layers of sediment and causing the alluvial fan to grow.

How Is an Alluvial Fan Formed