Topic 1A: Coasts (PAPER ONE) Flashcards
Abrasion
Waves throw pebbles against cliff & breaks off pieces of rock
Attrition
Pebbles bump into eachother
Solution
Sea water dissolves rock minerals
Hydraulic action
Force of water hits cliff and breaks off rock
Traction
Peebles roll along sea bed
Saltation
Particles/pebbles/sediment bounce along sea bed
Suspension
Light particles carried in water
Longshore drift
- Wave approaches beach at angle (prevailing wind)
- Swash carries particles up beach at angle
- Backwash carries them perpendicularly down the beach
Impact of joints and faults on coastal landforms
- Make rock less resistant to weathering
- Allow freeze thaw and plant root Weathering
- So, they are subject to mass movement forming caves arches and stacks
Concordant coastline
Rock layers run parallel to coastline
Disconcordant coastling
Rock layers are at an angle to coastline
How are concordant coastlines formed?
Same rock type means the coast erodes at the same rate = straight coastline and continuous line cliffs
How are discordant coastlines formed?
Different rock types
Soft rock layers erode faster forming bays
Hard rock layers erode slowly forming headlands
What is wave energy determined by?
Wind strength
Wave fetch
Destructive wave features
High energy
Large wave height
Frequent
Weak swash, strong backwash
Produce rapid erosion to form caves, arches, stacks, bays
Produce narrow, steep beaches
Constructive wave features
Low energy
Low wave height
Less frequent
Strong swash, weak backwash
Encourage deposition
Produce wide beaches
Headlands and bays
- Discordant coastline
- Less resistant rock is eroded faster (bays)
- More resistant rock is eroded slower (headlands)
Cliff formation
- Destructive waves attack bottom of rockface
- Hydraulic action and abrasion means the waves undercut the cliff to form a WAVE CUT NOTCH
The overhanging cliff eventually collapses as the notch gets deeper - This process repeats/continues
Wave cut platform
Gently sloping rocky area at the bottom of a retreating cliff
Cave formation
- Formed at headlands where rock is resistant
- Destruction waves break against headland and attack joints/faults (weaknesses)
- Hydraulic action and abrasion erodes the rock along the joint/fault so it increases in size, forming a cave
Arch formation
- Hydraulic action continues to erode a cave
- Trapped air is compressed, increasing pressure on the sides
- Back of the cave is pushed through to the other side, forming an arch
Stack and stump formation
- Erosion by the sea widens an arch and undercuts the base
- So, more pressure is on top of the arch which means it collapses to leave a stack
- Erosion and weathering over time causes stack to collapse to form a small flat stump
Beach formation
- Eroded material is transported by longshore drift and deposited by constructive waves along the coastline
Give some detail about the case study spit (what surrounds it and how)
East head spit in West Wittering: Area behind spit is sheltered , leading to deposition of silt and mud to create a salt marsh called Snowhill creek
