1. Weathering
The Breakdown of Rock

2. What are rocks?
Rocks are made from a combination of minerals and can be hard or soft depending on how the minerals are arranged.
Rocks can be found here…
…and here…
…and here…
…and here
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3. examples of erosion caused by weathering …
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4. The Needles, Isle of Wight
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7. 1890
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8. 1910
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9. 1940
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1975

11. Present day
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12. Freeze-thaw weathering
Physical
Freeze-thaw weathering
Extremes of temperature can cause rocks to break. Freeze-thaw weathering involves water getting into a gap in the rock and then freezing when the temperature drops. Water expands when it freezes and this puts pressure on the rock. The ice melts next day, the now larger gap again fills with water, freezes and so on until the rock breaks.

13. Physical Onion skin weathering
In very hot areas e.g. deserts, it is very hot during the day and very cold at night. This causes the surface of the rock to expand
and contract frequently until it eventually breaks off. This is called onion skin weathering (or exfoliation).

14. Onion skin weathering Draw a similar cartoon of your own
Extension: This type of weathering is common in particular places – where do you think these are and why?

15. Practical session. Please copy this table in your book (use a ruler)
Slide added by MGN( please hide if you don’t find it useful)
Write your conclusions:
e.g. ‘Chalk is a rock of white appearance, it can be scratched. Its dry mass was…. and its wet mass is now…. Hence is a porous rock.’
Follow the same structure for the rest of the rocks