Coastal Landforms 5.0 / 5 based on 1 rating ? GeographyCoastal zonesGCSEAQA Created by: 15changjCreated on: 21-09-19 09:49 Formation of Headlands and Bays Rocks of different resistance in alternating layers lay at right angles to the sea The sea erodes the rocks through the process of hydraulic action and abrasion. Less resistant rock is erroded at a faster rate Creates inlet in soft rock known as bay Areas of hard rock left jutting out in sea known as headlands 1 of 10 Formation of Headlands and Bay 2 of 10 Formation of a Sea Stack Natural cracks in headland Sea attacks cracks through processes of hydraulic action and abrasion Erosion is caused by pressurised air and powerful waves Expands crack to create a cave in side of headland Over time the cave is erroded all the way through the headland Creates an arch Arch is unsupported and subaerial processes such as rain can lead to the top of the arch becoming saturated with water Top of the arch becomes heavy and along with the force of gravity can lead to the top of the arch collapsing Leaves behind an isolated stack of rock - a sea stack 3 of 10 Formation of a Sea Stack 4 of 10 Formation of a Wave-Cut Platform Waves hit base of cliff Leads to erosion of base of cliff as they are pounded rocks, waves and pebbles. Abrasion and hydraulic action leads to formation of a wave-cut notch Erosion continues and an overhang develops Overhang increases in size Pressure on overhang increases due to sub-ariel processes e.g. heavy rainfall Rock is unable to support itself Rock collapses Process occurs again Leaves a layer of rock (wave-cut platform) at foot of cliff over time 5 of 10 Formation of a Wave-Cut Platform 6 of 10 Formation of a Coastal Spit Longshore drift moves sediment down a coastline due to the angle of prevailling wind When coastline changes direction longshore drift deposits sand in the sea Over time sand is deposited out at sea creating a long ridge of sand (spit) Spit eventually ends when sand reaches an area of water with high energy (e.g. river estuary) Area of water behind spit is sheltered and eventually forms a salt marsh Spit sometimes changes direction due to change in prevailling wind - creates hooked end 7 of 10 Formation of a Coastal Spit 8 of 10 Formation of a Coastal Bar Longshore drift moves sediment down coastline due to angle of prevailling wind When coastline changes direction longshore drift moves and deposits sand in the sea Coastal bar - ridge of sand that grows across a bay due to longshore drift Often creates a shallow lake (lagoon) behind them Lagoon eventually fills up with sediment or storm waves break through bar leaving lagoon exposed to sea 9 of 10 Formation of a Coastal Bar 10 of 10
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