1. Can you stick the freeze-thaw weathering paragraph into your book? Do now!

2. Last lesson Weathering of rocks – Freeze-thaw weathering

3. Freeze-thaw weathering In high mountainous areas, rain water can seep into the small cracks in a rock. At night-time the air gets very cold and the water freezes. When water freezes it expands making the crack wider. During the day the water melts and falls deeper into the now larger crack. This happens repeatedly, the crack gets bigger and bigger, and eventually a piece of rock is broken away from the mountain.

4. Educational freedom fighters! This class is being held hostage by educational freedom fighters (just outside). We have to decide as a class which is the most important word in the paragraph. If we get it wrong, they are going to shoot us!!!!!

5. Today’s lesson Chemical and physical weathering Transport The Rock Cycle

6. Can you gather around Mr Porter?

7. Chemical weathering Rain is slightly acidic as it contains substances dissolved from the air. It can react with rock, dissolving it.

8. Chemical weathering Some rocks are dissolved more by acid rain than others Limestone “pavement”

9. Physical weathering Rocks can be weathered by physical changes

10. Physical weathering When rocks are hot they expand, and when they cool they contract. Repeated changes cause the rock to crack, often causing rock to peel off. Sometimes called “onion-skin weathering”

11. Physical weathering Freeze-thaw weathering is another example You now know all about freeze-thaw weathering

12. Transport Rock falls to the bottom of rock faces and may be transported away by fast moving streams.

13. Abrasion The rocks in the stream bed rub against each other and wear away. This is abrasion.

14. Sediment The bits of rock in the stream bed are called sediment.

15. Deposit Smaller rock fragments are carried further than large ones, eventually being deposited on the bottom in slow water.

16. The Rock Cycle Can you read page 100 very carefully?

17. The Rock Cycle

19. Can you draw your own copy of the Rock Cycle? NO PEAKING!!!