Processes of coastal weathering, mass movement, erosion and associated landforms Flashcards
What types of processes combine to create distinctive landforms?
Sub-aerial processes and Marine erosion processses
What are the 4 sub-aerial processes?
Physical/mechanical weathering
Chemical weathering
Biotic weathering
Mass movement
What are the 4 types of Marine erosion processes?
Hydraulic action
Abrasion
Attrition
Corrosion
Examples of physical weathering
Freeze thaw - Repeated freezing and thawing of water results in expansion of cracks causing small fragments to break off
Salter crystallisation - Sea water evaporates from cracks allowing salt crystals to grow, exerting pressure and causing piece of rock to break off
Examples of Chemical weathering
Hydrolysis- Breakdown of rock by acidic water produces clay and soluble salts especially feldspar in granite.
Carbonation - Carbon dioxide that is dissolved in rain water creates weak carbonic acid (acid rain) which dissolves calcium carbonate in limestone
Examples of Biotic weathering
Plant growth - Roots of growing plants force their way into cracks and joints in rocks, increasing the pressure and causing particles to fracture
Animals - Burrow into weaknesses in soft rocks
Examples of rapid mass movement
Landslide - Rocks affected by physical weathering or marine erosion collapse downwards
Rockslide - Rocks slide down a cliff face when the bedding planes dip towards the sea
Examples of variable speed mass movement
Slump/mudslide - Saturated soft rock flows down hill (often on top of impermeable rock)
Rotational slip - softer rocks give way, moving downhill in one mass along a concave slip surface
Examples of slow mass movement
Soil creep - soil particles move downslope aided by raindrop impact
Solifluction - movement of wet soil downslope cause when underlying layers are frozen
What is hydraulic action?
Breaking waves creates hydraulic pressure in joints. The sheer force of the waves and compress air in cracks in cliff faces then the wave rushes out when the wave retreats. This can weaken the rock.
What is Abrasion/Corrasion
Rock fragments carried by waves wear away at the coast as the rock particles are being scraped over bare rock wearing it away and smoothing it.
Corrasion is where the waves hurl debris at the rock causing piece to be broken off wearing it away.
What is Attrition
Eroded rocks are worn smaller and rounder by constant rubbing against each other with the movement of the sea.
What is Corrosion/Solution
Weak acidic water chemically attacks certain rocks dissolving the minerals.
What is wave quarrying?
High-energy waves can exert a force of many tonnes per metre squared which can remove, love, unconsolidated rock fragments
