2B.4 Flashcards
What is fetch?
distance blown over which the wind has blown
What areas of the UK have large fetches?
Lands End in Cornwall over the Atlantic Ocean.
What areas of the UK have smaller fetches?
Dover in Kent, from weak English channel.
How do waves move across the ocean?
as ocean swells
How do waves break?
shallower watre = increases friction = base slows = top collapses
What are destructive waves?
where backwash>swash
What are constructive waves?
Where swash>backwash
What are differences between destructive and constructive waves?
Destructive = long fetch. higher energy, reduces beach material, flat beaches, Constructive = long wavelength, deposits sediment, low energy, builds beaches, short fetch
What are swell waves?
wave/ ocean systems that arent affected local winds creating flat waves.
How are swell waves created?
1) large scale winds blow
2) these travel 1000s of miles
3) over time the waves regulate
4) can be disrupted by storms
What are cross-seas?
Sea waves and one or more system of swell waves.
What is beach-morphology?
the dynamic shape of a beach including width and slope and other features as berms
What do summer beaches have?
steeper
Constructive wave
dissipated energy
What do winter beaches have?
destructive waves
undertows makes is dangerous
Why is steeper in summer?
because there is more deposition which is used to build up beaches.
What does backwash cause?
rip =drags sediment back as the next waves arrives over the top
Why do beaches change over time?
sediment supply varies (due to dams)
interference in supply (due to coastal management)
Changes in climate (uk shorter summer)
What is a storm beach?
high energy deposition of coarse sediment
What are berms?
shingle and gravel from summer deposition
What are offshore ridges/bars?
destructive waves erosion and deposition of sediment
What is a wave cut platform?
a gently sloping area of rock that is at the base of a cliff where waves converge.
How are wave cut platforms formed?
1) waves undercut forming a wave-cut notch
2) cliff collapses, the broken cliff erodes the remaining cliff
3) This repeats causing the cliff to retreat
What is an example of wave cut platform?
Whinnysfold Scotland cruden bay
What are the two main coastal erosion processes?
abrasion
hydraulic action
What is abrasion?
grinding sand along cliff foot
What is hydraulic action?
waves advance into small faults forces air into rock gaps the air is trapped then expands
What is attrition?
rocks banging together breaking apart
What is solution?
acids in the water dissolve materials eg Chalk calcium carbonate
What are coatal erosion landforms?
headlands and bays coves caves arches cliffs blowholes
What will global warming cause?
accidification of the oceans making erode cliff faces
What is a blowhole?
when a cave in a clifface with a vertical cliff upwards which is exposed to erosion and wave energy breaks the gap
What is aggrade of a beach?
builds up a beach increasing sediment.
What degrade of a beach?
erode beaches reduces sediment?
