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.
