Rivers: Processes of Erosion and Transport.

Erosion:

Erosion involves the wearing away of rock and soil found along the river bed and banks. Erosion also involves the breaking down of the rock particles being carried downstream by the river. There are four ways that a river erodes.

Hydraulic Action

The water forces air to be trapped and pressured into cracks in the rocks on the bank of the river. This constant pressure eventually causes the rocks to crack and break apart.

Abrasion

The erosion of the river bottom and the riverbank by material being carried by the river itself.

Attrition

The rocks and pebbles being carried by the river crash against each other, wearing them down to become smaller, rounded pebbles.

Solution

The chemical erosion of the rocks of the riverbank by the slightly acidic water. This occurs in streams running through rocks such as chalk and limestone.

Transportation:

Once it has been eroded, material in the river is transported down the river.Whilst this is happening, erosion processes such as attrition and abrasion continue to occur. There are four main processes of fluvial transportation,depending on the size of the material being moved:

Traction

large boulders and rocks are rolled along the river bed.

Suspention

Fine light material is carried along in the water.

Saltation

small pebbles and stones are bounced along the river bed.

Solution

Minerals are dissolved in the water and carried along in solution.

Watch the video below and see which of the methods of transportation you can see.

Task:

Create text book style diagrams that show each method of erosion and transport. If you would like, you could also produce an animation or similar.

Here is a good summary of the various fluvial processes.

Task: The Voice Over:

Watch the video and the produce a voice over to explain what you see. Try to include as many

geographical terms as possible.

The best way to do this is to watch the video and write your voice over using videonot.es

Geogrpahy in the News: July 1999

Canyoning Disaster in Interlaken kills at least 18.

What is Canyoning? Watch this