Coasts Flashcards
What’s a coastline
A place at which land meets the sea
What’s weathering
The break down of rocks at earths surface by rain water, temperature, biological, chemical and physical activity
What’s biological weathering
Roots from plants find a way into gaps in rock and weaken as gaps expand and widen so pieces fall off
Animal burrowing and walking over surface can wear away and weaken surface so prices fall away
What’s physical weathering
Wind can blow small grains of sand against rock and wear it away
Rain and waves hit rock - wear it away
Tell me about freeze thaw weathering which is physical btw
What expands when it freezes, so water enters cracks and freezes, the crack expands and when ice melts it can get further in crack and freeze and melt and so on until crack is so big the rock is to weak so it falls off
What’s chemical weathering
Reactions break down bonds holding rock together so they fall apart
More common in location with a lot of water as it is needed for for chemicals to reach the rock
What’s oxidation (chemical weathering)
When oxygen combines with other elements to make another type of rock, it’s broken down Becuase it’s become softer
What’s hydrolysis (type of chemical)
When water combines with substances in rock to form new substances which are softer than original rock
What’s carbonation (chemical)
Carbon Dioxide reacts with rock to become a solution and is carried away
What are mud slides, rock falls and slumping?
Types of mass movements
Tell me about mud slides
They occur on steep cliffs that have been weakened by weathering
The saturated mass falls down along a distinct SLIP PLANE which is likely a fault
Occur after heavy rain
Tell me about rock slide
Where a large amount of rock slides down the cliff, it happens along a fairly straight slip plane- something along natural plane in rock
Tell me about rock falls
Rocks prone to freeze thaw weathering result in falling rocks losing contact with cliff face
Need a vertical cliff and seasonal climates
At bottom of cliff they land and fan out to form a SCREE SLOPD
Tell me about slumping
Soft rock saturates permeable surface but stops at impermeable surface beneath, the saturated rock slips along curved plane towards beach
Happens again as waves undercut cliff base do its unstable and slumps
Define a mass movement
Downslope movement of rock or mud and soil under influence of gravity
Heavy rain usually triggers it
Scale of movement is determined by extent of weathering
What’s a wave
A body of water moving towards the coastline at a higher than average level
Tell me about waves approaching the coast
First there is a circular orbit in open water
Friction with seabed sorrows the circular orbital motion
There’s an increasing elliptical orbit at the top of wave moves faster
Wave begins to break
Then hits beach
What’s the backwash
ALWAYS AT RIGHT ANGLE TO SEA its water from a wave that returns
What’s swash
Water that rushes up the beach and goes up at angle of the wind
What’s a destructive wave like
High wave in proportion to length
A tall wave breaks downwards with great force near Beach
Long fetch
Short wavelength
Strong backwash
Weak swash
Created in storm conditions
Tend to erode coast
What’s a constructive wave like
Low wave in proportion to length
Strong swash
weak backwash
Long wavelength
Created in calm weather
Break at shore and deposit material to build up beaches
What’s the fetch
Distance wing travels to create a wave
Define erosion
Break down and removal of rock
What can affect rates of erosion
Rates of weathering
Power of backwash
Location
Fetch length
Rock type/resistance
Direction of wing
Shape of coastline
Human intervention
What’s attrition
Material carried by waves bump info eachother and are smoothed and broken down into smaller pieces
What’s hydraulic action
Waves enter cracks (faults ) in coastline and compress air within crack
When wave retreats the wake expands causing a minor explosion
What’s corrosion/ solution
Chemical action of sea water, acids in salt water dissolve rocks on the coast
Limestone and chalk prone to it
What’s abrasion and corrasion
This is a process where coast worn down by matieral carried by waves hit the rock sometimes at high velocity
What’s a headland
Area of resistant rock which protude (stick out) from coastline
What’s a bay
Area of soft rock between 2 headlands that erodes quickly
How does a bay form
When there’s is variation in rock type the softer rock erodes faster and over hundreds of years a bay is formed
What’s the difference between coves and bays
Coves due to rock type changing parallel to sea
Bays due to variation so bands of rock meet at a right angle to sea
Describe formation of a wave cut platform
Waves break on cliff face and erode
Erosion continues between high and low water mark and undercut(called a wave cut notch) rest of cliff face over hundreds of years
The notch becomes deeper and wider and overhand formed
The overhand collapsed and cliff retreats leaving a wave cut platform (bur of rock at bottom of cliff face)
Explain the formation of a stack
Lines of weakness in headland form form erosion
Continues to form a small sea cave
Over hundreds of year it deepens and widens to make a cave
Cave erodes back and breaks through other side forming an arch
Weathering breaks down roof of arch and collapsed leaving stack
Erosion weakens it to form a stump as it collapsed