Paper 1 Coastal Environments Flashcards
2.1a
Abrasion
Marine processes
Stone and sand in the water are forced against the cliff. This wears it down (like sandpaper).
2.1a
Attrition
Marine processes
Pebbles hit against eachother and are worn down. Eventually they become smoother and rounder.
2.1a
Hydraulic Action
Marine processes
Water is forced into cracks, forcing the rock to weaken. After long periods of time, material breaks away from the cliff face.
2.1a
Solution
Marine processes
Acids in the water cause the rocks to dissolve, particularly the soluble minerals. The rocks get smaller over time.
2.1a
Erosion
Marine processes
Movement of weathered rock away from the site of weathering by wind, water or ice.
2.1a
Wave height and length
Marine processes (Wave action)
- Strength of the wind (stronger wind = bigger wave)
- How long the wind has been blowing for (long time = bigger waves)
- The fetch: the distance over which a wave has travelled (big fetch = big waves)
2.1a
Crest
Marine processes (Wave Terminology)
The top of the wave
2.1a
Velocity
Marine processes (Wave Terminology)
The speed that a wave is travelling
2.1a
Wavelength
Marine processes (Wave Terminology)
The distance between two crests or troughs
2.1a
Trough
Marine processes (Wave Terminology)
The low area in between to waves
2.1a
Wave height
Marine processes (Wave Terminology)
The distance between the crest and the trough
2.1a
Wave frequency
Marine processes (Wave Terminology)
The number of waves per minute
2.1a
Why waves break
Marine processes (Wave Terminology)
When a wave approaches the coast its lower part is slowed by friction with the bed, but the upper part continues to move forward. As it is left unsupported, it topples over and breaks forward against the cliff face or surges up the beach, this is called wave break. The water that returns down the beach is called backwash.
2.1a
Swash
Marine processes (Wave Action)
Water that rushes up the beach when a wave reaches the shore
2.1a
Backwash
Marine processes (Wave Action)
Water from a previous wave returning to the sea
2.1a
Constructive Waves
Marine processes (Deposition)
Build up beach by depositing materials brought up by strong swash.
* Strong swash and weak backwash
* Shallow gradient waves (short waves)
* Long wavelength
* Lower frequency
* Spilling breakers
2.1a
Destructive Waves
Marine processes (Deposition)
Destroys beach by eroding material with strong backwash.
* Strong backwash and weak swash
* Steep gradient waves (tall waves)
* Short wavelength
* Plunging breakers
2.1a
Wave Refraction
Marine processes (Wave Action)
As aves approach a headland they become refracted. This causes wave energy to be concentrated on headlands leading to erosion and to be spread out in bays leading to deposition.
2.1a
Suspension
Marine processes (Transportation)
Material carried in the water
2.1a
Solution
Marine processes (Transportation)
Dissolved material
2.1a
Saltation
Marine processes (Transportation)
Bouncing along the bed: lifted and dropped repeatedly
2.1a
Traction
Marine processes (Transportation)
Roll along the bed
2.1a
Longshore Drift
Marine processes (LSD)
The transport of and pebbles along the coast is called saltation. The Longshore drift (the direction the prevailing wind usually blows from) causes waves to approach the coast at an angle. The swash carries the sand and pebbles up the beach at the same angle (usually 45°). The backwash however, carries the material back down the beach a 90° as this is the steepest gradient. The pattern repeats over time causing beach material to move along the coast in a zigzag pattern.
2.1a
Marin processes
Caused directly by the sea, e.g. erosion, transport and deposition
2.1a
Sub-aerial processes
Take place above the high tide level on the land. e.g. weathering and mass movement
2.1a
Weathering
Breakdown of rock in place and does not involve movement.
2.1a
Mechanical weathering (Freeze-thaw weathering)
Cracks in the rocks get wet and filled with water at night the temperature drops below 0℃. Water in the cracks freezes and as water freezes it expands. The cracks become wide because of this and then the temperature rises above 0℃ causing the ice to thaw and contract. This process is continued (widening the crack) until the rock is broken.
2.1a
Chemical weathering
Chemical weathering occurs when rainwater which contain Carbon dioxide (making it a weak carbonic acid) reactions with Calcium Carbonate in rocks such as limestone and chalk. This dissolves and is washed away in solution, weakening the rock over time.
2.1a
Biological weathering
Living things such as burrowing animals and plants attacking rocks and weakening their structures. Plants roots can grow in cracks. As they get bigger they push open the cracks eventually making the rocks fall apart.
2.1a
Mass movement
All downhill movement of material under the influence of gravity. The process cause the cliff to retreat backwards and provides material for the marine processes.
2.1a
Rockfall
The rapid fall of rocks from the face of a cliff because of the action of gravity. This is made worse by freeze thaw loosening the rock. Bare, well-jointed rock. A scree slope of fallen rock is formed at the bottom of the cliff.
2.1a
Landslide
Blocks of rock detach themselves from the cliff and slide downhill along side a slide plane. The rock accumulates at the bottom of the cliff and is removed by the sea.
2.1a
Slumping
Rapid movements of a mass of earth or rock sliding along a concave slip plane. Undercutting of a steep slope by the seas weakens the rock above making a slump more likely. Can occur after periods of heavy rain.
2.1c
Formation of headlands and bays
The hard and soft rocks determine the geological structure as they are affected by erosion differently from eachother. They form along discordant coastlines.
2.1c
Discordant coastlines
The rocks out crop at 90° to the coastline, and bays and headlands are formed along this coastline due to differential erosion.
2.1c
Concordant coastline
Only have one rock type which is parallel to the coastline.
2.1c
Wave cut platforms
At high tide the power of the sea erodes the bottom of the cliff by processes such as hydraulic action and abrasion. Over time this erosion creates a wave cut notch. As the wave cut notch gets bigger, undercutting occurs and the weight of rock above the notch gets greater. Eventually the cliff cannot support its own weight and it collapses. The process then starts again, with the erosion of the sea making a new wave cut notch. As the process continues the cliff starts to move backwards. Because the cliff is moving backwards a wave cut platform (an expanse of bare rock) is created. Wave cut platforms are only visible at low tide and is smoothed down by the wave action.
2.1c
Cliff erosion
A cliff’s shape varies with:
1. The nature of the rock (geology)
2. Its bedding (angle of dip)
3. The presence or absence of bands of weaker rock
2.1c
Formation of caves, arches, stacks and stumps
- Crack opens up as waves erode a weakness in the rock
- Cave crack widens tnrough erosion to form a cave
- Cave ends all the way through the headland to produce an arch
- Subaerial processes weaken the top of the arch which eventually collapses leaving a stack
- Stack is eroded and weathered down to a stump
- More erosion
2.1c
Beach profile
A cross section of a beach from the high water mark to the low water mark.
2.1c
Factors that influence beach profiles
- Sediment size
- Wave type (constructive or destructive)
- Tidal range
2.1c
Shingle beaches
Coarser, larger material is carried to the top of the beach as the swash is usaully stronger than the backwash. (Constructive waves)
2.1c
Formation of a spit
- Follows the prevailing wind direction
- Constructive waves and the swash push sediment up the beach
- Backwash moves sediment down the beach
- Sediment moves along the beach in a zig-zag pattern
- Sand and shingle is moved along the coast by longshore drift
- Sediment is deposited in sheltered water as the current slows down and there is insufficient energy to carry the sediment
- Sediment builds up above the level of the sea
- Sediment comes to a change in the direction of the coastline
- If a spit grows across the river a bar forms and a lagoon
- Coast is sheltered and shallow
- Saltmarsh and sand dunes build up behind the spit
2.1c
Sandy beaches
Backwash carries smaller, finer material back down the beach. (Destructive waves)
2.1b
Metamorphic Rocks
Hard and resistant rocks including granite and basalt. They form headlands in discordant coastlines. Are are tall and steep with rocks at the base.
2.1b
Igneous Rocks
Influence of geology on coastal environments
Hard and resistant rocks including granite and basalt. They form headlands in discordant coastlines. Are are tall and steep with rocks at the base.
2.1c
The difference between a spit, bar and tombolo
A spit cuts across the sea cutting off a lagoon behind it. If a spit joins from mainland to an island it is called a tombolo. A bar is from mainland to mainland and forms similarly to spits.
2.1b
Sedimentary Rocks
