Weathering = the breaking down of rocks by the action of the weather, plants or chemical action.
Physical weathering (wetting + drying): softer rocks expand when wet and contract when dry out. This continued expansion and contraction can weaken rocks and make them more easily eroded.
Chemical weathering (corrosion): sea water is very corrosive & can slowly dissolve chalk and limstone, increasing size of cracks/joints so erosion is more effective. Salt spray can get into cracks + when it evaporates, crystals are formed which can force them apart.
Biological weathering = the action of nesting/burrowing animals breaking down rocks.
Marine erosion- 3 types
Abrasion- during storms, waves pick up sand and pebbles. As waves break, material is hurled at cliff face. This 'sandblasting' effect is the most powerful source of coastal erosion in the UK.
Hydraulic action- the sheer force of waves breaking against a cliff causes parts of it to break away. As waves hit a cliff face, air is compressed into cracks, blasting away fragmants of rock.
Attrition- sand+pebbles are constantly colliding as they're moved by waves breaking on a beach. This wears away beach material, making it increasingly smalled and more rounded.
*Marine erosion is the weathering of rocks caused by the sea.