Booklet 6- What weathering and erosion and how do they affect the coast? Flashcards
Type of Weathering-Freeze thaw
During the day, water enters cracks in the rock and at night when the temperature drops the water expands as it freezes. The increase of volume by 9% exerts pressure on the fissures of the rock and weakens it internally.
-During the day, when the temperature rises again, the ice melts. The process reoccurs repeatedly until the rock breaks apart. The material is then loose and then falls onto the shore
Type of Weathering-Insolation
Thermal fracturing; repeated changes in temperature weaken the rock
Type of Weathering-Salt
Like freeze thaw, but caused by expansion of salt crystals; creates piles of weathered debris called regolith
Type of Weathering-Hydrolysis
In certain rocks with minerals that are reactive to water or chemicals in the water.
-This is where particular minerals break down due to their contact with water leading to loss of rock coherence and structure
Type of Weathering-Oxidation
Occurs on cliff faces and shoreline rocks where iron elements are present within rocks. The ‘rusting’ of the iron content may cause rocks to disintegrate
Type of weathering-Exfoliation
This occurs when the daytime and night-time temperatures are distinctively different on dry rock. During the day, the sun heats up the surface of the rock and at the night the outer layers cool down.
Type of weathering-Biological
On cliff faces, both animal and plant action can loosen large amounts of rock material. Trees and plant roots can prise apart rocks by growing in between the bedding planes and joints enlarging them as they increase in size.
-Equally damaging is when small animals burrow underground and loosen rocks such as sand martians. Microorganisms in the soil are also able to break down the rocks; particularly carbonate rocks
-However, plants soak up water which can prevent saturated soils which are more likely to slump, mass move
Positive feedback in weathering
1) Weathering weakens the cliff
2) Material is picked up and removed by the sea faster than it is deposited
3) This provides material for erosion to use
4) This speeds up erosion and weakens the cliff more
5) Weathering can happen more easy in the future
Negative feedback in weathering
1) Weathering weakens the cliff
2) Material is not picked up by the sea
3) Debris is deposited at the bottom of the cliff
4) This provides a barrier between the sea and the cliff
5) This slows down erosion
6) The cliff is not weakened
How is weathering affecting the Holderness Coast?
Weathering is speeding up the formation of coastal landforms
Weathering causes mass movement> as sediment slumps or slides downhill under gravity
-slumps the coastal landscape as Boulder Clay is prone to weathering
Sub-ariel definition
Weathering above the sea
Run-off definition
Water thats not soaked into the surface
Percolation definition
Downward movement of water within the surface
Sheer strength definition
The rock strength, how likely it is to collapse
How will climate change affect weathering?
Increased chemical weathering due to more acidic rainfall
-Physical weathering is also likely to increase due to more extreme temperatures and variations in temperature and rainfall
-The chalk cliffs at Flamborough head are likely to be attatched quicker by increased chemical weathering from acidic rain but also more acidic oceans due to ocean acidifications
-Chalk cliffs are calcium carbonate
