River processes Learning objectives: 1.Understand the different types of weathering 2.Know what mass movement is 3.Understand the different types of erosion and transportation 4.Understand how material is deposited

Running water has a significant influence on the development of landforms. Before we learn about these landforms, we need to understand the processes that shape them, as well as the factors affecting these processes: 1. Weathering and mass movement 2. Erosion 3. Deposition

What are the differences between these three rivers? Why do differences occur?

Activity Copy and complete this paragraph… Rivers are always at work changing and shaping the surface of our world. When rivers have lots of energy the water wears away rock, stones and soil from their bed and banks, this is called _____. The rivers then carry this material downstream, or _____ it from one place to another. When the river loses some of its energy it cannot continue to carry the material so it drops it, this is known as _____.

Part 1 (a) What is weathering? Weathering happens when rocks are attacked and broken up by the weather, particularly through rainfall and significant variations in temperature. There are 3 main types of weathering: 1.Physical weathering 2.Biological weathering 3.Chemical weathering

Your challenge... You will be working in groups and you will receive some information on the following topics to help you explain the processes that happen in deserts: Physical weathering Chemical weathering Biological weathering  Using the information you have, you need to create a presentation with a maximum of 10 words – use picture representations that you will then explain to your classmates 10 mins

Your next challenge One person will be the teacher The other people will go and find out about one other process You will need to take notes as you will be explaining it to the other members of your group. 10 mins

What is going on in this photograph? A landslide – this is a hazardous form of mass movement. Mass movement often initially results from weathering because the rock becomes ‘loose’.

Part 1 (b) Mass movement in river valleys There are two main types of mass movement in river valleys. Using the explanations below, draw an annotated diagram to explain these two processes: 1.Slumping – this happens when the bottom of the valley side is cut away by the river flowing at its base. This makes the slope unstable and weathered material slopes down towards the river. Slumping is also helped when the weathered material on the slope is saturated by heavy rain. The water makes the weathered material heavier and also acts as a lubricant. Slumping of large amounts of material often leads to a landslide. 2.Soil creep – when weathered material moves slowly down a slope under the influence of gravity. It collects at the bottom of the valley side and is eroded by the river. 15 mins

Part 2. What is erosion? Erosion is the wearing away and removal of the land by wind and water. 20 mins

How much do you know about erosion? Using the next slide to help you, try to complete the first section of the worksheet

Processes of river erosion Hydraulic action Attrition Corrosion / Solution Abrasion

Processes of River Erosion Hydraulic Action Abrasion Attrition Corrosion / Solution

You are about to take part in the secret art of erosion kung fu… Hydraulic Action: make punching movements with hand- demonstrates force of water hitting river bank. Abrasion: make a throwing gesture with hands like you are throwing dealing cards very rapidly Attrition: make 2 fists, and then bring them towards each other, hitting each other, then open hand to resemble a stone breaking. Corrosion: have arms out stretched in front of you, waving fingers, and moving arms downwards. Sound effect of something dissolving is needed.

How much do you know about transportation? Once the river contains eroded material or any type of ‘sediment load’, it transports it downstream. Try to match the correct terms with the illustrations on the diagram.

Part 3. What is deposition? Deposition: is the laying down of material transported by the river – this occurs when there is a decrease in energy, speed and discharge of the river. It often happens when the river enters a lake or the sea, or wherever there is a decrease in the gradient of the river’s channel 5 mins

Odd one out Saltation Traction Abrasion Suspension Physical Mass movement Biological Chemical Saltation Solution Attrition Hydraulic action Steep gradient Low energy Decrease in discharge Low velocity Slumping Deposition Weathering Mass movement

Odd one out - answers Saltation Traction Abrasion Suspension Physical Mass movement Biological Chemical Saltation Solution Attrition Hydraulic action Steep gradient Low energy Decrease in discharge Low velocity Slumping Deposition Weathering Mass movement