What is the deposit on the inside bend of a meander called

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What happens on the inside bend of a meander?
What is the inside of a meander on a river called?
What is deposition meander?
Why is material deposited on the inside bend?

A meander is a winding curve or bend in a river. Meanders are the result of both erosional and depositional processes. They are typical of the middle and lower course of a river. This is because vertical erosion is replaced by a sideways form of erosion called LATERAL erosion, plus deposition within the floodplain.

The image below shows a series of meanders. Notice the deposition on the inside of the meanders (pale material) and the river cliffs or bluffs (indicated by dark shadows) on the outside of the meanders.

A series of meanders

Again, the image below shows a series of meanders. The river shown in the photograph is swollen due to recent rainfall. Once again we can see deposition on the inside curves of the meander.

A swollen river

Erosion, transportation and deposition are all processes that create the characteristic features of meanders shown in the images above.

The videos below shows meander initiation and braiding in a small river model.

There are several stages involved in the creation of meanders. These are discussed below.

Stage 1

In low flow conditions straight river channels have bars of sediment on their beds. Flowing water weavers around these bars of sediment. This creates deeper pathways where most of the water flows called pools and shallow areas where less water flows called riffles. This causes the river flow to swing from side to side.

The map below shows bars of sediment exposed due to the low level of water in the channel. Notice how the flow of water weaves around the sediment bars.

View Larger Map

Stage 2

Where the river swings towards the bank erosion causes undercutting. On the opposite side of the channel where the velocity is lower material is deposited. Therefore the river does not get any wider. The image below shows evidence of undercutting on the outer bank and deposition on the inner bank of the meander.

Stage 3 in the formation of a meander

Stage 3

Continued erosion along the outer bank, as the result of hydraulic action and abrasion, creates a river cliff or bluff. A point bar forms on the inner bank. This is a gently sloping deposit of sand, gravel and pebbles. The image below shows a point bar.

Point bar

Stage 4

Meanders are perpetuated through a process called helicoidal flow. As the surface flow of water hits the outer bank it corkscrews, flows along the river bed then deposits eroded material on the inner bank.

Step 5

Erosion is greatest beyond the middle of the bend in the meander. This causes the meander to migrate downstream over time. By looking at aerial photographs it is possible to see former channels on the floodplain.

What happens on the inside bend of a meander?

The force of the water erodes and undercuts the river bank on the outside of the bend where water flow has most energy due to decreased friction. This will form a river cliff. On the inside of the bend, where the river flow is slower, material is deposited, as there is more friction. This will form a slip-off slope .

What is the inside of a meander on a river called?

On the inside bend of the river, known as the point bar, water velocity is slower because it doesn't have to travel as far as the water on the outside of the bend. This allows sediment to settle out and be deposited. As this cycle of erosion and deposition continues, the river will migrate in it's river valley.

What is deposition meander?

Slower moving water erodes material more slowly. If water is moving slowly enough, the sediment being carried may settle out. This settling out, or dropping off, of sediment is deposition. The curves are called meanders because they slowly “wander” over the land.

Why is material deposited on the inside bend?

Erosion on the outside of the bend is caused by the fastest flowing water hitting it. This creates a river cliff. Deposition occurs on the inside of the bend due to the water being forced to slow down. This creates a slip off slope.