Costal Landscapes Flashcards
(24 cards)
Caves, arches, stacks & stumps formation
Stage 1
All rocks have lines of weakness. The sea and its waves use hydraulic action, abrasion, attrition and solution to erode along many lines of weakness. Undercutting takes place all around the headland
Caves arches stacks stumps
Stage 2
These lines of weakness get enlarged and developed into small sea caves
Caves arches stacks stumps
Stage 3
These caves are deepened and widened on both sides of the headland, until eventually the sea cuts through the headland, forming an arch
Caves arches stacks stumps
Stage 4
The rock at the top of the arch becomes unsupported as the arch is enlarged, eventually collapsing to form a stack
Caves arches stacks stumps
Stage 5
The stack gets eroded until only a stump remains
Caves arches stacks and stumps
Stage 6
Overtime the stump will disappear
Caves arches stacks stumps
Stage 7
As the headland retreats under this erosion, the gently sloping land at the foot of the retreating cliff is called a wave cut platform
Wave cut platform 1
Waves attack the base of the cliff, the waves erode the base of the cliff by hydraulic action and abrasion
Wave cut platform 2
The erosion creates a wave cut notch, as the notch becomes larger the upper part of the cliff is unsupported
Wave cut platform 3
Erosion continues and undercuts the base of the cliff, erosion continued and the upper cliff becomes less stable and eventually collapses
Wave cut platform 4
As the process continues the cliff will slowly retreat and move inland, as the platform enlarged the cliff has greater protection. The gently sloping land at the foot of the cliff is called a wave cut platform
Headlands and bays
These form along coasts that have alternating resistant harder rock and less resistant softer rock. Where there is resistant rock the coast will be worn away slower, leaving a headland which sticks out into the sea. Where there is softer rock; erosion will be more rapid and a bay will form. As the headland becomes more exposed to the full force of the wind and waves, it will become more vulnerable to erosion than the sheltered bay
The size of waves is determined by
The speed of the wind
The length of time the wind has been blowing
The distance of sea it has travelled (the fetch)
Hydraulic action
Hydraulic action is the sheer force of waves crashing against the shore and cliffs. The power of the waves forces air into the cracks, compresses it and blows the rock apart as the pressure is released
Attrition
Attrition happens when rocks and pebbles carried by the waves smash into eachother, wearing eachother away and gradually becoming smaller, rounder and smoother
Abrasion
Abrasion is the process of rocks and pebbles carried by the waves wearing away rocks as they are thrown against cliffs
Solution
Solution is when chemicals in the sea water dissolve Minerals in the rocks, causing them to break up
Spit (1)
Spits form where the coastline changes direction and longshore drift continues to move the material along the beach
Spit (2)
Longshore drift will deposit material in the sea after the coastline has changed direction
Spit (3)
Overtime the level of the sand deposited will build up until it is above sea level
Spit (4)
The spit cannot develop right across the bay as a rivers estuary prevents the build up of sand
Spit (5)
Sand spits often have a curved or hooked end. This is created when secondary wind and wave direction causes waves to strike from a different direction
Spit (6)
The beach therefor appears to extend out into the sea and is known as a spit or sand spit
Spit (7)
The spit creates an area of calmer water, sheltered by the spit, a lagoon, salt marsh and dry land can develop in this sheltered area
