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Weathering in granite landscapes
Granite mineralogy
• Large irregular crystals – which is which?– Quartz– Feldspar– Biotite
• When and how was Dartmoor’s granite formed?
Granite structure
• Describe the structure of granite – how were the joints formed?
• Is granite permeable?
Granite and weathering• Granite is susceptible to many types of
weathering. Describe how the following processes denude the granite– Hydrolysis– Chelation– Freeze-thaw– Organic action
Tors
• The most characteristic landform of a granite landscape is the tor.
• What is a tor?
• Name two areas of the British Isles where granite tors are found.
Theories of tor formation
• The explanation for the formation of tors and been subject to some controversy
• There are two main theories:– Linton– Palmer and Neilson
• Draw detailed, labelled diagrams explaining the two theories.
Joint control in granite landscapes
This model shows a granite landscape inSW England viewed from above. Thereare two vertical joint sets at right angles to each other. Areas of granite with widely-spaced joints (massive zones) give ridgesand tors; areas with closely spaced joints are more easily weathered and give basins.The streams follow joints and tend to haveright-angle bends – a rectilinear drainagepattern.