These are SO important for your exam. You must be able to name these processes and also EXPLAIN how they work…here’s a summary -
GLACIATION
WEATHERING - the physical and/or chemical break-up of solid rock on the earth’s surface, producing loose debris.
EROSION - the removal of weathered rocks by moving water, wind, ice, or gravity.
For an explanation of weathering and erosion see this video – designed for primary school but easy to understand!
FREEZE-THAW (AKA Frost-Shattering or Frost-Action) – a form of physical weathering which happens in mountains and glacial environments, caused by the expansion of water as it freezes. Water in a crack freezes and expands in volume by 9% as it turns to ice. This expansion exerts great pressure on the rock, causing the crack to enlarge. After many cycles of freeze–thaw, rock fragments may break off to form scree slopes. Here is a pic of a scree (talus) slope created by freeze-thaw weathering :
PLUCKING – a type of erosion. This is where melt water in the glacier freezes onto rocks, and as the ice moves forward it plucks or pulls out large pieces along the rock joints.
ABRASION - a type of erosion. This is when rocks and stones (picked up by the glacier through plucking) are rubbed against the bedrock at the bottom and side of the glacier, as the glacier passes, pulled down hill by gravity. This causes wearing on the landscape. Abrasion sometimes results in striations (scratches on the bedrock)…..
ROTATIONAL SLIP - When ice is trapped in a corrie unable to move down hill, gravity will still encourage it to move. In a glacier, circular motion is known as rotational slip. This movement together with plucked debris causes further erosion through abrasion.
LIMESTONE
COASTS
HYDRAULIC ACTION - This is caused by the force of waves rushing into cracks in the rockface. The water compresses the air in the cracks. As the waves retreat, the highly pressurised air is suddenly released with explosive force, capable of chipping away the rockface over time. So the cracks gradually get bigger and pieces of rock are carried away by the sea.
ABRASION (Corrasion) - This is a form of wave erosion. Pebbles, boulders and rocks are thrown against the cliff face by breaking waves. This causes undercutting of the cliff and leads to the breakup of both the cliff and the objects being thrown against it.
CORROSION - This is when cliffs are eroded by weak acid in seawater.
