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Geography Revision 2010
Transcript of Geography Revision 2010
1. Waves are caused by wind blowing over the surface of the water.
Longshore drift occurs when the prevailing winds cause the
waves to approach the beach at an angle. 2. The breaking wave surges diagonally up the beach at the angle of
the approaching waves. The breaking water that washes up on the
beach is called SWASH. The swash gradually slows down as it washes
up the beach to it's highest point. 3. After reaching the highest point, gravity causes water to drain straight back down the slope of the beach. The water that washes back down the beach is called BACKWASH. 4. This process is repaeated every time a wave breaks on the beach. As a result, sand and pebbles move in a zig zag motion down the beach. This process is known as LONGSHORE DRIFT. wave erosion.. attrition When rock fragments grind and rub each other down to give smaller fragments. For example, rocks are smoothed to pebbles, then to shingle and eventually to sand. abrasion/corrasion Broken rock fragments and pebbles carried in the wave, batter and scour the land, breaking off other pieces of rock and rubbing surfaces down.
hydraulic power When a wave crashes into the land it compresses air and water trapped in carcks on the surface of the rock. When the wave moves away again, the compressed air expands explosively. Both these actions enlarge the cracks and ultimately result in bits of rock breaking off. corrosion This is a chemical action of sea water on rock. For example, limestone dissolves on sea water and some sea salts can react with certain rocks and break them down. caves, arches, stacks & stumps caves, arches, stacks & stumps 1. Waves are very strong where headlands just far out into sea.
These waves will attack any FAULTS or CRACKS in the rocks. 2. CAVES can form at the base of cliffs, where these cracks
have been worn down by erosion, 3. Caves can forn on the opposite side of the headland and, over time, may meet and join to form a natural ARCH through the cliff. 4. Futher erosion and weathering will eventually cause the arch
to become unstable and collapse. This leavesbehind pillars of rock
called STACKS. 5. The base of the stump is eroded and weathered until eventually the
top falls off, leasving behind a STUMP. wave cut platforms 1.