How do characteristics of coastal landforms contribute to global landscapes Flashcards
What are the different erosional processes
Hydraulic action
Abrasion
Attrition
Corrosion (solution)
What are the definitions of the erosional processes
(Hydraulic action and Abrasions)
Hydraulic action - Wave impacts a cliff face and air if forced into cracks under high pressure widening them creating instability
Abrasion - Repeated actions of waves removing material which is then thrown back at the cliff creating a sandpaper effect
What are the definitions of erosional processes
(Attrition and solution)
Attrition - Beach material is knocked together in the water reducing their size and increasing roundness and smoothness
Solution - Carbon dioxide dissolves in the water turning it into weak carbonic acid which several rocks are vulnerable to a dissolve in
What is percolation
Water moves through permeable rock
Well will most erosion occur
- When waves are at their largest which is influenced by wind speed and fetch meaning they have high energy
- High wind propelling waves higher up the cliff
- Heavy rainfall and percolation of water through permeable rock weakens the cliff
what is the
- Waves
- Orbit
-Swash and backwash
- Beach profile
like in a destructive wave
. Waves - High waves above 1 meter, Short wave length so they are frequent
. Orbit - Circular orbit which becomes elliptical due to shore friction slowing the base of the wave
. Swash is weaker than the backwash so less sediment is deposited
. Beach profile - steep beach with sand and rock particles
what is the
- Waves
- Orbit
-Swash and backwash
- Beach profile
like in a constructive wave
. Waves - Low waves bellow 1 meter, Long wave length so low frequency
. Orbit - circular orbit which becomes elliptical due to friction
. The swash is more powerful than the backwash so sediment is deposited
. Beach profile - gently slopping beach with sand
.
What is beach morphology
Ridges and runnels
and a Berm
. Beach morphology - Shape of a beach, including the width and slope and features such as berms, ridges and runnels. Also the type of sediment
. Ridges and runnels - Ridges are areas of the beach that are raised above the adjacent shore which dips into a runnel
. Berm - A ridge of sand formed at the back of a beach just above the high tide line
What are summer beach profiles like
- They are a result of constructive waves
- The back wash is weaker than the swash so more sediment is deposited
- Berms are built up due to sediment being deposited
What are winter beach profiles like
- They are a result of destructive waves that are high frequency so erosion occurs quickly
- Strong backwash compared to a weak swash
- Berms are quickly eroded
What are the different types of transportation
- Traction
- Saltation
- Suspension
- Solution
What are the definitions of the types of transportation
. Traction - Sediment rolls along by being pushed by waves and currents (pebbles, boulders)
. Saltation - Sediment bounces along due to the force of water or wind (sand sized particles)
. Suspension - Sediment is carried in the water column (silt and clay)
. Solution - Dissolved material is carried in the water as a solution (chemical compounds in solution)
Describe to process of longshore drift
Swash carrying material deposits it at an angle due to prevailing winds. The backwash transports the sediment back into the sea at a 90 degree angle
How is a spit formed
Created by longshore drift as a change in the direction of the land occurs but the longshore drift still deposits material horizontally creating a deposit of sediment
What are sediment cells
- Sediment moves along the coastline in sediment cells
- In each cell the sediment moves between each cliff, beach and sea via erosion, transportation, deposition etc
- Any action that takes place in one part of the cell impacts the rest of the cell
- Each cell operates between physical barriers preventing the sediment from moving further (e.g. headlands)
- The coastline of England and Wales is divided into 11 cells
What are the sources of sediment cells
- Erosion of cliffs
- Land sediments eroded by rivers
- Onshore currents supplying sediments to the shore
- wind blown (Aeolian) sediments from land
- Sub ariel processes
- Shells and remains of marine organisms
What are the transfers of sediment cells
- Longshore drift
- Wave transport
- Tides moving sediments inland out to sea
- Currents - localised or large scale
- Wind - alongshore or on and offshore
What are the sinks of sediment cells
- Backshore - depositional landforms e.g. sand dunes
- Foreshore - depositional landforms e.g. beaches
- Nearshore - depositional landforms e.g. bars
- Offshore sediment deposition to deep offshore waters
Describe dynamic equilibrium in sediment cells
- The amount of sediment available within a cell is called the sediment budget
- In each cell features build up which are in equilibrium with the amount of sediment available
- If the budget falls waves continue to transport sediment (erosion may increase in some areas) one change leads to another which is known as positive feedback
- If the budget increases then more deposition is likely. This is negative feedback
Whole balance in the cell is referred to as dynamic equilibrium
What is a spit and how is it made
- Made of sand or shingle
- Sand or shingle is moved across the coast by longshore drift and will begin to be deposited and built up even when the coastline suddenly changes direction (e.g. due to river estuary)
- Outward flow of the river if a spit forms will prevent it from extending the fill width of the estuary
- End of the spit will also begin to curve as wave refraction builds sediment behind it (recurved spit)
How are drift aligned beaches and Swash aligned beaches formed and what are their features
. Drift aligned - Produced where waves break at an angle to the coast. Swash then occurs at an angle but back wash is perpendicular to the beach. Material is transported along the beach by longshore drift . Finer shingle particles which are rounder are best transported
. Swash aligned - Waves break in line with the coast. Swash and backwash move material up and down the beach. Curved, concave beaches parallel to fronts of dominant waves
How are Bar/barrier beaches made
- Where a beach or spit extends across a bay to join 2 headlands e.g. star bay in Devon
- Barrier beaches and bars can trap water behind them to form lagoons
- Where a beach is separated from mainland = barrier island
What are Tombolo’s and how are they formed
- A beach that has formed between a small island and the mainland
- Deposition occurs where waves lose their energy and tombolo’s begin to build up
What is cuspate foreland and how is it made
- Triangular shaped headland that extends out from the main coastline
- Occurs when a coast is exposed to longshore drift from opposite directions and sediments is deposited where the two meet
- Vegetation helps to stabilise the landform and protect it from storms that could erode it
