traction saltation suspension solution particles of rock are dissolved in the water and carried...
TRANSCRIPT
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
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.
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.
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
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