•Coasts 3 Flashcards
(68 cards)
What is an example of a fast process?
Longshore drift
Deposition
What is an example of a slow process?
Weathering
Why have we had major fluctuations?
Over the past 2 million years as a result of glaciation
What is an instantaneous scale?
Landforms that are affected by changed operating within a single cycle so within seconds to days to weeks
What are event time scales?
Ones that operate across a time span from an individual event through to seasonal variations which may take place from a few days to a few years
What is an engineering time frame?
When fluctuations take place over longer fine scales ranging from years to decades and centuries
What is a geological time scale?
From decades to Millenia as change takes place in sea level and climate
What is an example of an instantaneous landform?
Beach
What is an example of an event landform?
Sand dune
What is an example of an engineering landform?
Stack
What is an example of a geological landform?
Spit
What will influence the rate of change at a coast?
Fetch Waves Tides Wind Mood Prevailing wind
When did the last ice age end?
11,500 years ago
What is the process of a stack?
Wave-cut notch formed by erosion such as wave pounding which creates weaknesses in rocks
Caves form by further erosion such as wave quarrying
Arch formed from undercutting where erosional processes such as hydraulic action have occurred
There are weaknesses caused by weathering e.g solution
Sub-aerial processes occur on top of the cliff
Stack formed as weathering processes like carbonation cause an arch to collapse
Cliff recession is caused by erosion and slumping
A wave-cut platform is exposed at low tide
What does vertical erosion create?
Blowholes
How does a spit form?
Longshore drift carries a supply of sediment along the shoreline
Where the coastline changes direction, material is deposited in the open sea by longshore drift
Material accumulates over time so that it lies above the level of the water and a spit develops
Vegetation begins to grow, Helios from to colonise the spit
The end of the spit it shaped by waves from other directions so that it forms a hook
If sediment continues to be supplied, the spit may grow beyond the hook
What is a tombolo?
A spit joining an offshore island to the mainland
What is a barrier Island?
Barrier islands as found in seas with shallow gradients close to the shore
They form as a result of deposition by constructive waves
Formed in areas where tidal ranges are low
Formed parallel to the shoreline
What are the reasons for the location of the formation of barrier islands?
The accumulation of material transported by swash or wind-blown sand
The isolation of the shore when sea levels rise; higher storm beaches and sand dune ridges are left isolated
The emergence of previously submerged offshore bars as sea levels fall
Spits being heavily built up by storm waves but then breached, forming a series of islands
Why can a bar only form across a bag with no major flow?
Because the energy from a flow will move sediment and stop it from being deposited as deposition will only happen in calm water
Why might bars in the Uk be made of flint?
There is flint on the floor of the English Channel which will have been washed up during sea level change 6,000 years ago
What is a cuspate foreland?
A low-lying, almost triangular area of coast where sediment is deposited
What are the reasons for the formation of a cuspate foreland?
Waves from different directions create two converging spits
Deposition of sediment from fluvial sources causes a build-up of material
Changes in coastline over thousands of years have led to changing patterns of deposition
What is the difference between a ridge and a runnel?
Runnels run at right angles to the directions of maximum fetch
