Upland areas
contain igneous and metamorphic rock resistant to erosion
Lowland areas
contain sedimentary rock
Mass movement
Movement of rocks and land down a slope due to gravity
Slides:
material shifts in a straight line along a slide plane
Slumps:
Material rotates along a curved slip plane
Rockfalls: material breaks up along bedsing planes, and falls down a slope
Traction
large particles are pushed along the sea bed by force of water
Saltation
pebble sized particles are bounced along the sea bed by the force of water
Suspension
small particles like silt and clay are carried along in the water
Solution
soluble materials are dissolved in the water and carried along
Deposition
occurs when water carrying sediment loses energy and slows down
Coasts build up when depositon > erosion
Headlands and Bays
Form when there is a discordant coastline. The less resistant rock are eroded faster, forming a bay with a gentle slope. The resistant Rock erodes slower so forms steep sides
Caves Arches Stacks Stumps
Resistant Rock that makes up headland has weaknesses like cracks
Wave crash into the headlands and enlarge the cracks through erosion (hp, abrasion)
Repeated causes caves to form
Erosion continues which deepens the cave until it forms an arch
Continues to wear away the rock supporting the arch until it eventually collapses
This forms a stack, though stack is eroded to form a stump
Wave cut platforms
Wave cause erosion at the foot of a cliff creating a wave cut notch, enlarged
Repeated erosion leaves the rock above notch to be unstable and collapse
The collapsed material is washed away and a new wave cut notch fstarts to form
After repeating collapses the cliff retreats leaving a wave cut platform
Beaches
Formed by deposition
Sand beaches are created by low energy waves that are flat and wide
Shingle beaches are created by high energy waves and are steep and narrow
Spits
Form at sharp bends in the coastline
Longshore drift transports sand + shingle past the bend and deposits it in the sea.
Strong winds and waves can curve the end of the spit.
The area behind the spit is sheltered from waves, so material accumulates and plants are able to grow.
Over time, the sheltered area can become a mud flat or a salt Marsh
Bars
A bar forms when a spit joins 2 headlands together.
The bay between the headlands gets cut off from the sea.
This means a lagoon can form behind the bar.
Offshore bars can form if the coast has a gentle slope - Friction with the sea bed causes waves to slow down and deposit sediment offshore creating a bar that is not connected to the coast.
Sand Dunes
Formed when sand is deposited by longshore drift and is moved up the beach by wind.
Obstacles decrease wind speed so sand is deposited, forming small embryo dunes.
Embryo dunes are colonised by plants e.g Mahram grass. Roots of vegetation stabilise the sand, encouraging more sand to accumulate there. This forms foredunes and eventually mature dunes.
Dune slack can form in hollows between dunes
