2.1 Shaping the landscape - Coasts Flashcards
How are waves formed?
They are formed by wind interacting with the surface of the sea.
When do waves break?
The waves break when the base is slowed by the sea bed at the coast
What is fetch?
The distance over which the wind blows over the sea surface
The greater the fetch, the __________
larger the waves are as the wind is able to blow over it for a greater amount of time
Why is the largest wave height in the UK in the South Western side?
The waves in the South West have an incredibly long fetch
What is the prevailing wind direction?
The direction from which the wind usually blows
What is hydraulic action?
When waves crash against the cliff, compressing the water and air into cracks and forcing the rocks apart.
What is abrasion?
When waves pick up rocks from the sea bed or beach and smash them against the cliffs
What is corrosion (solution)?
when minerals such as calcium carbonate (the main part of chalk and limestone rocks) are slowly dissolved in seawater
What is attrition?
When sand and pebbles are picked up by the sea and smashed against one another, wearing them down into smaller and more rounded particles
What causes sea levels to rise?
Extreme low pressure weather events (depressions)
What are storm surges?
A rapid rise in sea level caused by low-pressure storms
What is mass movement?
The sudden slumping/slip of sediment in cliffs due to water infiltration from above and erosion at the cliff base causes the cliff to collapse
What affects the rate of erosion
the rock type at the coast
what type of rocks in cliffs get eroded very easily?
soft unconsolidated boulder clay
what type of rocks in cliffs are more resistant to erosion?
limestone and chalk
what is suspension
fine material such as clay and sediment is carried by the sea
what is traction
large boulders and pebbles are rolled along the sea bed
what is solution
dissolved minerals are carried by the sea
what is saltation
small stones, pebbles and silt bounces along the sea bed
what is the impact of human activity on erosion
Human activity also causes changes to the dynamic coastal system.
Tourism that brings footfall to coastal footpaths can accelerate rates of erosion and weathering and make them unstable.
Building structures for industry or coastal management also changes sediment dynamics and can have devastating knock-on effects at other parts of the coast.
what is deposition
the laying down of material due to loss of wave energy
Describe how headlands and bays are formed
when harder rock (limestone and chalk) are located next to softer unconsolidated sediments (clay and sand), the latter is eroded at a faster rate by the waves.
the more resistant rock protrudes as a headland while a bay is formed from the softer rock.
the bay is more sheltered from the wave energy and deposition occurs forming a sandy or shingle/pebble beach
what is a wave cut notch
when waves break at the base of sedimentary rock cliffs, higher rates of erosion occurs forming a wave cut notch
what is a wave cut platform
an area of exposed rock below the wave cut notch
this is visible at low tide
is the surface of a wave cut platform smooth
no, because erosional processes like abrasion and weathering continue to erode the rock face
as a result, vertical joints and potholes are formed
draw an annotated diagram to show how caves, arches, stacks and stumps are formed
what is longshore drift (LSD)
when the prevailing wind blows waves to beaches at an angle, the sediment is transported along the coastline in a process called LSD
what is the movement of the wave up the beach called
swash
what is the movement of the wave back down again
backwash
draw an annotated diagram to show LSD
describe how a spit is made
A spit is a narrow strip of land that forms along coastlines through sediment buildup.
This happens when waves, pushed by the prevailing wind, carry sediment along the shore.
As this continues, the sand starts to pile up in the same direction, creating a spit that extends into the water.
If a secondary wind changes the wave direction, the end of the spit can curve, forming a hook shape.
The waters behind the spit often become estuaries and salt marshes.
draw an annotated diagram of a spit
what do salt marshes and estuaries do
they support the high biodiversity of plants and animals
