Processes of erosion and transportation Flashcards
Define marine erosion
processes that operate upon the coastline related to the sea
What are the 5 kinds of marine erosion
Attrition
Abrasion
Hydraulic action
Quarrying
Solution
What is attrition
when pieces of rock in water smash into each other to make smaller pieces
What is abrasion
when pieces of rock in water smash into rocks and cliffs, breaking pieces off
What is hydraulic action
Erosion due to the sheer force and energy of a wave, exerting enormous amounts of pressure on the rock. When he wave pulls away there is a drastic change in pressure
What is quarrying
When waves hit a rock they trap air. The wave compresses this air into any gap on the cliffs face, creating an enormous amount of pressure.
Once the wave pulls back, an explosive effect occurs as the air pressure is released
What is solution
When soluble rocks are dissolved by seawater
Define Sub-arial erosion
processes that operate upon the coastline not related to the sea
What are the 3 kinds of Sub-arial erosion
Freeze thaw weathering
Biological weathering
Chemical weathering
What is freeze thaw weathering
When water repeatedly freezes and melts in a rocks cracks. Water expands by 9% when it freezes, putting pressure on the rock and causing it to break off
What is Biological weathering
Weathering related to the surrounding wildlife such as paddock fish drilling into rock
What are the 4 types of chemical weathering
Oxidation
Hydration
Hydrolysis
Carbonation
What is chemical weathering
Weathering due to the lithology of a rock
What is oxidation
When oxygen dissolves in water, it reacts with rock minerals to form hydroxides, which effect iron rich rocks, turning them a copper colour
What is hydration
When water reacts with a rocks minerals, the rock expands causing stress. This causes cracks in the rocks.
What is hydrolysis
When mildly acidic water mixes with a rocks minerals, turning them into a clay like material, meaning they become eroded more easily
What is carbonation
When Co2 enters the ocean it creates carbonic acid. This reacts with calcium carbonate in rocks to form calcium bi-carbonate, which dissolves easily in water. This can also be causes by sulphuric and nitric acids in acid rain
What factors effect the rate at which a coastline is eroded
Geology of coastline
Coastal configuration (physical features)
Human activity
Type of waves
What 3 geological factors effect the rate of erosion
Lithology
Strcuture
Concordant or Discordant
How does lithology (chemical composition of a rock) effect erosion
Weak rocks - clay, sand, gravel
Strong rocks - Chalk, limestone, granite
How does structure of a rock effect erosion
Stratas (layers)
Dips (angles) - horizontal are the steepest, and seaward sloping are more gentle
Faults (cracks)
What’s the difference between concordant and discordant coastlines
Concordant are parallel to the coastline and steep
Discordant are perpendicular to the coastline and flat
What are the 2 types of erosion
Marine erosion
Sub-aerial erosion (weathering)
What are the 3 types of transportation
Mass movement
Marine transportation
Sub-aerial transportation
What is transportation
transportation is the movement of sediment
What is mass movement
the downslope shifting of unconsolidated material caused by through flow and runoff
What are the 5 types of mass movement
Slumping
Mudslide
Landslide
Rockfall
Soil creep
How do landslides occur
When the top layer of earth slides beneath the bottom layer due to saturation
How to mudflows occur
When fine materials become saturated and flow down a slope
How does slumping occur
When soft weak rock along a curved surface becomes saturated and slumps towards the sea
How does soil creep occur
When soil particles become saturated, they expand and are lifted away from the slope at a right angle. Gravity pulls these particles back down, causing a slow downward movement
What are the 4 kinds of marine transportation
Traction
Saltation
Suspension
Solution (dissolved material)
What is traction
When large boulders and rocks are pushed along by water
What is saltation
When small stones bounce along the sea bed or when the wind is strong enough to pick up and carry small particles of sand
What is suspension
When small particles are carried by water
How does longshore drift occur
Swash carries sediment up the beach, parallel to the prevailing wind. Backwash carries the sediment down the beach at right angles to the shoreline. When there is an angle between the prevailing wind and shoreline, sediment is moved
