1. EROSION

2. What is Erosion?
Erosion is the removal and breaking down of soil and rock from the Earths surface by natural processes
The movement of weathered material from one point to another is known as erosion

3. As pieces of rock are moved ,
ATTRITION & ABRASION
ATTRITION
As pieces of rock are moved ,
they knock against each other and are
broken down into smaller pieces . This
process is called attrition

4. ABRASION
As these small pieces of rock are moved across the surface , the rocks become smoother or they cut into the surface , this process is known as abrasion

6. The forces that cause rock to break up : Agents of erosion
Flowing Rivers
Sea
Moving Ice
Wind

7. DIFFERENCE BETWEEN WEATHERING , EROSION AND DEPOSITION
Weathering is the process of breaking up a rock into smaller pieces . During this process the smaller pieces of rock remain at the point they have been weathered and are not moved .
Erosion is the process by which the weathered
material is moved, and the rock breaks down further while being moved.
Deposition is the putting down or dropping of smaller rock pieces to make new landforms.

9. RIVERS –
FEATURES OF EROSION
AND DEPOSITION
ALONG A RIVER COURSE

11. Rivers are one of the most important geographical landforms created, they are an interaction in both human and physical geography.
In the river the processes of erosion and deposition occur.
A river flows from it source, the point of its origin a high lying area with steep gradients eg. a mountain top, towards the mouth a low lying area with a rarely flat surface eg. a dam or the sea

12. The movement of water in a river occurs at different stages and can be at a fast moving speed or a generally slow speed or in between.
As the river flows this force of water and pressure that exists moves the rock ,stone ,sand and other sediments along the river this is erosion occurring.

13. The three sections of a river
The three sections of a river are called river courses and are described as :
Upper course : A steep slope with a narrow valley
Middle course : This has a medium slope and a wider valley
Lower course : This has a gentle slope or is flat and a wide valley.

15. Features of the upper course
Narrow v- shaped valley
This part of the river has a lot of energy because of the steep slope. The energy is used to erode a steep and deep river channel . The river has lots of large rocks in the river bed.

16. Potholes
Potholes are round deep holes found in the bed of a river , they are formed when a rock gets stuck in the bed of a river. The force of the water causes the rock to spin or turn . The turning of the rock is like a drilling action causing the rock to erode a round hole in the river bed forming a pothole .

17. Rapids and Waterfalls
A rapid is formed when resistant rock in the river bed causes water to flow over and around the rocks .

18. Waterfall A resistant layer of rock does not erode easily
A waterfall is formed when a hard or resistant rock layer in a river bed causes a steep slope or vertical drop.
A resistant layer of rock does not erode easily

20. Subject Teacher : Social Studies
IN THE NEXT LESSON
We going to look at the features of the middle course and lower course
We going to look at how the Sea and wave action acts as an agent of erosion.
THANK YOU
Compiled by :
A Ellan
Subject Teacher : Social Studies
Geography