Question

When is sediment most likely to be deposited? When the ______.

Multiple choice question.
a) grains have a surface area to volume ratio above 2:1
b) current velocity increases again after a brief slowdown
c) sediment supply exceeds a stream's capacity to transport it
d) tributaries reach the next order of stream in the drainage basin

Answer 1

Sediment is most likely to be deposited when the sediment supply exceeds a stream's capacity to transport it, typically as the stream widens, the current slows, and tributaries increase the volume of water and sediment.

Step-by-step explanation:

When is sediment most likely to be deposited? The correct answer is c) sediment supply exceeds a stream's capacity to transport it. This situation occurs when the stream or river can no longer carry the sediment due to factors such as decreased water velocity, which can be the result of increased channel width, reduced gradient, or an increase in sediment supply, causing the sediment to settle and be deposited.

This typically happens as the river or stream flows away from the source and eventually widens, the current slows, and more tributaries join, increasing the volume of water and sediment transported. At this stage, the decreased velocity of the river is insufficient to keep the sediment in suspension, leading to sediment deposition.

This process is illustrated by features such as graded bedding, where different sediment layers are distinguished by the size of their grains, reflecting a gradient in the energy of the sediment transport environment.