TRACTION

SALTATION

SUSPENSION

SOLUTION

Particles of rock are dissolved in the water and carried along without being seen.

Large boulders and rocks are ‘rolled’ along the bed of the river.

Smaller pebbles and stones are ‘bounced’ along the bed of the river.

Smaller particles of silt and sand are held within the water and transported along in the flow of water.

Transportation

ABRASION

CORROSION

ATTRITION

HYDRAULIC ACTION

Erosion The sheer force of the water removed material from the bed and banks of the river.

Material is rubbing against the bed and banks of the river wearing them away.

Some rock such as calcium carbonate dissolve in the water if it is slightly acidic.

The load itself being carried, bang into each other and break up and become smaller and smaller.

EROSION

TRANSPORTATION

DEPOSITION

River Processes

The wearing away and removal of rocks by the action of water, wind or ice

The movement of sediment along the river’s course

The putting down of material by the river

LO: To explain how a river meander forms and develops into an oxbow lake.

All of you will be able to describe the processes that form a meanderMost of you will be able to describe how a meander becomes an oxbow lakeSome of you will be able to explain why meanders and oxbow lakes form.

Meanders & Ox Bow Lakes

The Plenary

C-D Must be able to describe the process that leads to the formation of meanders.

A*-B Must be able to explain the process that leads to the formation of river meanders.

GeogingoChoose five words from the following

Hydraulic action

Freeze thaw

infiltration

transfer

store

abrasion

attrition Surface run off

evapotranspiration

V shaped valley

waterfall

deposition

transportation

River Tees Upper Course

River Tees Middle Course

We are going to look at a land processes that takes place in the middle stages of a river.

We are going to look at a Meanders.

Water in a meander bendWater in a meander does not all travel at the same speed. The fastest and most powerful water travels around the outside of the bend.

Think about being in the back or a car when going round the corner…

Or being on a rollercoaster and being thrown to one side of the carriage.

http://www.stacey.peak-media.co.uk/year7/7-7Rivers/7-7Meanders/7-7Meanders.htm

Meanders

As the course of a river reaches its middle stages it flows over flatter land. Lateral (sideways) erosion happens because of fast moving water on the outside of meanders.

Meanders constantly change their shape and position.

A

B

Where is there more erosion? Why?Where is there more deposition? Why?

Draw a river in your book. It should be about a 1/3 of a page high and as wide as your page.Make sure it has bends it in like this one:

Using a different colour mark on your river the route of the fastest water.

Where the red line hits the banks – it erodes material.In the areas of the river the water is travelling slower, the water has less energy and so deposits the eroded material.

6. Add to your diagram where deposition and erosion are taking place

Lateral Erosion

Deposition

= Lateral Erosion

= Deposition

Video

DepositionErosion

Meander = a bend in a river

River cliff deposition river beach lateral erosionundercutting slowest current fastest current

Oxbow lakes

Meanders3. 1.What is a meander?

2.What sort of land do they form on? Flat or steep?

3.Which side of a meander erodes the banks? Why?

Meander neck becomes smaller

new course of the river

oxbow lake

When the river floods it breaks through the thin meander neck and the river takes the easier, straight course.

This cuts off the meander loop leaving an oxbow lake. Over time, the oxbow lake gets filled in and overgrown.

4. Explain the formation of an oxbow lake

Explain the formation of an oxbow lake