Weathering - Sub Ariel Process Flashcards
What is weathering
The disintegration of rock in situ. There are 3 main types of
Physical weathering
Occurs when rocks are broken down by physical factors such as wind, water and temperature change
Chemical weathering
The breakdown of rocks because the interaction of air, water or acid with the chemical composition of the rock
Biological weathering
Breakdown of rock by plants, animals and microorganisms eg plant root enlarging cracks in rocks as they grow
Wetting and drying
PHYSICAL WEATHERING
rock alternates between wet and dry. Some rocks such as shale expand when they are wet and contract when they dry causing cracks to form in the rocks
Exfoliation
PHYSICAL WEATHERING
rock may expand as it is heated by the sun and contracts when it cools. This can cause cracks to form in the rock.
Freeze thaw
PHYSICAL WEATHERING
water that fills the cracks in rocks freezes when temperatures are low and the ice expands and exerts pressure within the rock, enlarging the cracks
Crystallisation
PHYSICAL WEATHERING
the high salt content of the sea water can lead to the growth of salt crystals within the rock that exert pressure on joints and lead to fracturing
Oxidation
CHEMICAL WEATHERING
rocks containing iron compounds experience oxidation when exposed to oxygen and water from the air and the sea which causes disintegration
Carbonation
CHEMICAL WEATHERING
coastlines are composed of chalk or limestone are dissolved by acidic rain and sea water
Roots of plants
BIOLOGICAL WEATHERING
the roots of plants on cliff tops can create and expand tiny fissures. Sub surface seaweed can also attach to rocks and weaken them during movement
Surface animals
BIOLOGICAL WEATHERING
surface animals like puffins may excavate nesting burrows in cliffs, sub surface creatures like limpets may also remove rock when they attach to it
