 Take the title “Landscape Evolution”  Task:  Discuss with number 9 date all the different things that cause landscapes to change. 2 minutes  Now write your ideas down. 2 minutes

 Glaciers scraping the landscape.

 Rivers/the sea eroding landscapes and coasts

 The weather has a great affect on the landscape too.

 Rocks that are exposed on the Earth’s surface become vulnerable to weathering. Weathering is the disintegration (breaking up) and decomposition (decay) of rocks in their place of origin. Weathering, unlike erosion, need not involve the movement of material.  Can you think of different ways that the land could be work away?

 Physical Weathering is the disintegration of rock into smaller pieces by physical processes without any change in the chemical composition of the rock. It can often occur on bare rock where there is no vegetation to protect the rock from extremes of weather.

 Freeze-thaw, or frost shattering occurs in cold climates when temperatures are around freezing point and where rock contains many cracks. Water enters cracks during the day and freezes at night. As the water turns into ice it expands and exerts pressure on the surrounding rock. Repeated freezing and thawing widens the cracks and causes pieces of rock to break off.  Exfoliation or onion weathering occurs in very warm climates when exposed, non-vegetated rock is repeatedly heated and cooled. The surface layers heat up and expand more rapidly during the day and cool and contract more rapidly at night than do the inner layers. The rock begins to peel off, like layers of an onion.  Biological weathering is when tree roots penetrate and widen bedding planes and other weaknesses in the rock until blocks of rock become detached.

 Chemical Weathering is the decomposition of rocks caused by a chemical change within the rock. It is more likely to occur in warm, moist climates, as these encourage chemical reactions to take place.  Limestone solution is caused by carbonic acid (carbon dioxide in solution) which occurs naturally in rainwater. Although it is only a weak solution, it reacts chemically with rocks such as limestone which contains calcium carbonate. As the limestone slowly dissolves, it creates very distinctive scenery.

 People who were missing – you need to get some discussion partners.  Draw a clock in your jotter and put the numbers 12, 3, 6 and 9 on it.

 You are going to be put in groups of 4.  You will each have 40 seconds to describe one thing that we covered in the last lesson.  (If you were not here miss your turn and the next person will just speak).

 It is important to understand weathering so that we can understand how the different types erosion work.  chemical-weathering-by-solution-in- upland-limestone-scenery/4704.html chemical-weathering-by-solution-in- upland-limestone-scenery/4704.html  how-does-weather-change-the-shape- and-appearance-of-mountains/325.html how-does-weather-change-the-shape- and-appearance-of-mountains/325.html

 Collect a diagram on weathering and a copy of the Physical Geography textbook.  Stick the diagram in to your jotter and then annotate around it with detailed notes on different types of weathering. P94+95 of the physical core book.

 Rock type  Rock porosity and structural weakness  Climate  Local conditions

Weathering: All processes where rock is loosened or disintegrated over time. Mass Movement: Downward movement of weathered material due to gravity and accelerated by rainfall. Erosion: From rivers or glaciers. Transportation: The movement of eroded or weathered material. Deposition: When the material is finally deposited by river or glacier.

 Although mass movement is not part of weathering it is still an important part of the process of landscape evolution.

 You will be put into 4 groups  You must turn to pages 96 and 97 of the Physical Geography textbook.

 Group 1: Rockfall  Group 2: Mudflow  Group 3: Landslip (slumping)  Group 4: Soil creep