Chapter 28, Problem 9TE

In the formation of a river delta, why are larger particles deposited first, followed by smaller particles farther out?

To determine

The reason of larger particle depositing first followed by smaller particles farther out in the formation of a river delta.

Answer to Problem 9TE

In the formation of a river delta, the larger particles deposit first followed by smaller particles farther out because the forward momentum of the flowing water decreases gradually.

Explanation of Solution

In the direction of the flow of a stream the forward momentum of the flowing water decreases gradually. With decreased energy, the velocity of water slows and the river cannot carry larger sediments. Hence, the larger sediments get deposited first. These sediments form a fan-shaped deposit known as river delta. Further with reduced energy and lower velocity only the smaller particles are carried forward by the flowing water depositing them farther offshore.

Conclusion:

Therefore, in the formation of a river delta, the larger particles deposit first followed by smaller particles farther out because the forward momentum of the flowing water decreases gradually.