Coasts Flashcards
Fully explain hydraulic action
• The power of the waves forces air into cracks, compresses it and blows the rock apart as the
pressure is released.
Fully explain solution
• Soluble rocks react with acids or salts in the water, slowly wearing away as they do so
Fully explain abrasion
• Abrasion is the process by which waves throw rocks and pebbles at cliffs.
• The impact of this means the cliffs are worn away.
Fully explain attrition
• Attrition happens when rocks and pebbles carried by the waves smash into each other, wearing each other away
• Gradually becoming smaller, rounder and smoother
• This aids the process of abrasion
Fully explain cliff formation
• Weathering attacks the top of the cliff (wind and rain)
• Destructive waves attack the base of the cliff forming a wave-cut notch.
• This is the result of erosion by abrasion, hydraulic action, solution* and attrition*.
• As the cliff is undercut, the rock above lacks support and collapses
• The material from the collapse slopes out into the ocean to create a wave cut platform
• Due to this continued process the cliff slowly retreats inland (backwards) until the sea can no
longer reach it
Fully explain cave/arch/stack formation
• Waves erode a weakness in the rock (joint / bedding plane) through
hydraulic action, abrasion, solution* and attrition*.
• Overtime this enlarges into a sea cave.
• Through continued erosion the back wall of the cave can be eroded
all of the way through, forming an arch
• Continued erosion can widen the feet of the arch. Eventually the top
of the arch becomes unsupported and will eventually collapse,
forming a stack
• Overtime the base of the stack will be eroded, causing further
collapse, creating a platform of rock called a stump
Fully explain headland and bay formation
• Bays and headlands form where alternating bands of rock meet the coast at right angles
• Differential erosion occurs as soft rock is eroded faster than hard rock.
• This happens through the processes of
hydraulic action, abrasion, solution* and attrition*
• The soft rock is eroded to form a bay, while the hard rock forms a headland
• As time progresses, headlands become more eroded as they are more exposed.
• Bay less eroded as it is more sheltered.
Fully explain longshore drift
• The waves approach the shoreline at an angle, usually (45°).
• These waves are called swash and they are controlled by the
prevailing wind.
• The waves are pulled back out at (90°).
• These waves are called backwash and are controlled by the force of
gravity
Fully explain sandpit formation
• A sandspit is a wedge of sand which builds up in the sea.
• The process of longshore drift* occurs and this moves material along the coastline.
• As longshore drift continues, the coastline suddenly changes direction.
• The sand keeps on moving in the original direction, even though there is not a coastline to follow.
• Continued deposition allows the sand to
build up in the ocean.
• The sea has to be relatively shallow and sheltered to allow the accumulation of sand.
• Sometimes a curve develops if the on- shore wind changes direction.
• A salt marsh often develops in the
sheltered land behind the spit.
Fully explain sandbar formation
• A bar is a barrier of sand which joins two headlands and stretches across a bay.
• The process of longshore drift* occurs and this moves material along the coastline.
• As longshore drift continues, continued deposition allows the sand to build up across the bay.
• The sea has to be relatively shallow and sheltered to allow the accumulation of sand.
• This continues until the sandspit stretches across the bay, joining the two headlands, to form a sandbar.
• It can cut off a lagoon to the landward side.
• A lagoon is a body of brackish water- part salty, and part fresh. It often supports specialised plants and animals, and is protected as a nature reserve.
