1. Erosion and Weathering

2. What is weathering
The process that breaks down rock and other substances. Heat, cold, water, ice, and gases all contribute to weathering.
The forces that wear down mountains like those that cause bicycles to rust, paint or peel and sidewalks to crack. Erosion works continuously to weather and carry away rocks at Earth’s surface

3. Types of Weathering
Mechanical (Physical) - no change in chemical composition.
Frost wedging
Salt wedging
Chemical - decomposition of rock through a chemical change in its minerals.
Oxidation - important in iron-rich rocks
Hydrolysis - igneous rocks have much silica which readily combines with water
Carbonation - carbon dioxide dissolved in water reacts with carbonate rocks to create a soluble product (calcium bicarbonate)

4. What is erosion? The process of wearing down and carrying away rocks.
Erosion includes the breaking of rocks into smaller pieces. It also involves the removal of rock particles by wind, water, ice, or gravity
corrosion: erosion by chemical action

5. Types of Erosion
Water
Wind
Glacier
Soil
Sea

6. Water
Occurs from chemicals in the water and the force and flow of water
Chemicals break down certain rocks like limestone or chalk
Force of water creates cracks and crevasses
These get bigger and bigger as it gets eroded, particles of the rock get carried in the water and further aid erosion

7. Wind The wind picks up smaller particles of rock (pebbles and sand)
These hit landforms and take pieces off them
This friction causes the break up of landforms

8. Glacier Erosion What is a GLACIER?:
A huge mass of ice slowly flowing over a land mass, formed from compacted snow in an area where snow accumulation exceeds melting
These large bodies of ice that pick up rocks and earth and erode the earth’s surface
Powerful eroding machine, picking up pieces of rock the size of houses in some places
Glaciers are so powerful they can carve valleys and create landforms

9. Sea Erosion Salts and other chemicals in the water erode coastal rocks
These are dragged out to sea and deposited in other areas (Long shore Drift)
Wave power creates erosion. Also particles of rock and sediment aid to the erosion process

10. Soil Erosion Biggest problem for farmers
Wind and rain remove topsoil and nutrients
Makes the soil infertile and it breaks up leaving dongas

12. TASK
You are a forester in South Africa and you have just acquired some land and you are faced with a problem with soil erosion due to poor farming techniques:
YOUR PROBLEM:
DONGAS CASUED BY EROSION HAVE TAKEN UP CRITICAL SPACE FOR YOU TO PLANT AND GROW TREES
WHAT STEPS ARE YOU GOING TO TAKE TO REPAIR THE DONGAS?
WHAT IMPROVED PLANTING TECHNIQUES ARE YOU GOING TO USE?

13. RUBRIC Rubric for task 1 2 3 4 5 Total 15 Steps to combat problem
Just outline
Just points
No steps good points
Good outline good points
Very good step by step outline with relevant points and techniques
Repair Dongas
Just technique no explanation
No technique vague explanation
Adequate technique and vague explanation
Good technique, adequate explanation
Relevant techniques and clear explanation of techniques
Improved faming methods
Little effort made
Adequate methods no explanation
Adequate methods and adequate explanation
Good methods and good explanation
Excellent methods and explanations
Total 15