- Created by: lgjones
- Created on: 12-10-17 09:01
Types of Weathering
Physical Weathering-Internal pressures are exerted on rock as a result of changes in th physcial structure and it's mass
Chemical Weathering-Both rain and seawater contain chemicals that can react with chemical compounds in the rock, altering it's structure
Biological Weathering-Living organisms can contribute to the weathering of coastal rocks through the activity of plants and animals
Types of Chemical Weathering
Types of chemical weathering are-
Oxidation is when rocks containing iron compounds experience oxidation (rusting) when they are exposed to oxygen and water from the air and the sea. This causes disintergration of the rocks.
Carbonation is when coastlines which are composed of chalk and limestone are dissolved by acidic rain and seawater.
Types of Physical Weathering
Types of physical weathering are-
Wetting and drying-wetting and drying is when rocks alternate between being wet and dry. When the rocks are wet they expand, when they are dry they contract. This forms cracks in the rocks.
Crystallisation-crystallisation is when the high salt content of sea water can lead to the growth of salt crystals within the rocks, this puts lots of pressure on the rock and causes it to start fracturing.
Exfoliation -exfoliation is when rocks expand when they are heated and contract when they are cool. This causes cracks to form in the rocks
Freeze Thaw-freeze thaw is when water fills gaps in rocks and freezes and the ice expans putting pressure on the rock, this widens cracks.
Types of Biological Weathering
Types of biological weathering are-
Roots of plants
This is when roots of plants on cliffs create and expand tiny fissures, this weakens the rocks.
Anmals that live on the surface often create burrows in the cliffs, this weakens the rock causing cracks.
There are 6 main types of erosion-
Hydraulic Action- this is when waves break against a cliff face and water is froces into cracks which compresses the air inside.
Cavitation- this is when the opening up of cavities within the cliff due to changes in pressure as waves crash into and out of cracks in the rock.
Abrasion- the launching of rock fragmenst and pebbles against a cliff by the waves can break off pieces of solid cliff and weaken structure.
Quarrying-this is when destructive waves in storm conditions plunge heavy hydraulic pressure on cliff face. The vibration of the cliff can dislodge bits of rock and undercut the base of the cliff.
Solution-chalk and limestone is dissolved and rock is removed in solution.
Attrition-the smoothing and reducing of angular rock fragments into pebbles, shingle and eventually sand particles.
Rockfall-rockfall is when hard bits of rock breaks off from the cliff and moves down the slope at a rapid speed due to gravity.It is a type of collapse and is a dry type of mass movement.
Landslides-landslides are a rapid rapidly. They often occur after very heavy rainfall as the land becomes saturated and friction is reduced causing it to slide. It can be a wet and dry type of mass movement.
Runoff-runoff is a type of flow and is a fairly rapid type of mass movement. It occurs when water and small particles are moved down a slope or cliff.
Mudflows- mudflows are a fast moving , it is a wet kind of mass movement and it a type of flow. They occur when weak rock such as clay gets water trapped in it's pores and this leads to slope faliure.
Slumping-slumping is a rotational type of mass movement. It is quite slow moving and can be wet and dry. It occurs when permeable rock lies ontop of impermeable rock this causes a build up of water pressure in between the two rock causing it to slump.
Soil creep-it is the slowest type of mass movement. It is a type of flow,it is when individual soil particles expand and contract.