What kind of sediment is deposited in the river delta?

In a river delta, the velocity of the river water decreases as it enters the standing water body (usually an ocean or a lake). This sudden decrease in velocity causes the river to deposit its sediment load. The coarsest sediments, such as gravel and sand, are deposited first, closest to the river mouth. As the water spreads out and slows down even more, finer sediments, such as silt and clay, are deposited farther away from the river mouth.

Here is a detailed description of the different types of sediments deposited in a river delta:

1. Near the River Mouth:

- Topsets: These are the coarsest sediments deposited near the river mouth. They consist of gravel, sand, and coarse silt. As the river enters the calmer water of the receiving basin, its velocity decreases, causing the larger and heavier particles to settle down.

2. Delta Front:

- Foresets: These are inclined layers of sediment deposited on the delta front. They consist of sand and silt and form as the river's sediment-laden water flows down the delta slope and comes to rest. Foresets dip in the direction of the basin.

3. Prodelta:

- Bottomsets: These are fine-grained sediments deposited beyond the delta front, in the basin or lake. They consist primarily of silt and clay particles carried by the river's currents and deposited in the quiet, deeper waters. Bottomsets are typically horizontal or gently inclined.