Coasts Flashcards
how are waves created?
the action of the wind blowing over the water, it creates friction and causes a swell. The energy of the wind causes the swell to grow and move forwards as a wave.
what is fetch?
how far the wind had travelled uninterrupted (larger fetch = larger wave)
why do waves break?
as they approach the coast, the friction between them and the ocean floor causes them to break. the sea floor slows down the base of the wave but the top keeps moving and eventually falls over due to gravity.
what is the energy of a wave determined by?
-how long the wind has been blowing
-the strength of the wind
-how far the wind has blown (fetch)
name 4 characteristics of a destructive wave
-higher
-shorter wave length
-weak swash
-strong backwash
name 4 characteristics of a constructive wave
-low
-long wavelengths
-strong swash
-weak backwash
what kind of beach does a destructive wave create?
a steep beach
what kind of beach does a constructive wave create?
a gentle, sloping beach
give two examples of mechanical weathering and what they are
-salt weathering - crystals of salt grow in cracks and cause fragments to break off
-freeze-thaw weathering - repeated cycles of freezing and thawing of water trapped between the rocks causes fragments of the rock to break off
name three types of chemical weathering and what they are
- hydrolysis - acid rainwater reacts with granite causing it to crumble
-oxidation - oxygen dissolved in water reacts with iron rich minerals and makes them crumble
-carbonation - carbon dioxide dissolved in rainwater forms weak carbonic acid. this reacts with calcium carbonate to form calcium bicarbonate which is carried away by water.
name the one type of biological weathering and what it is
living organisms like nesting birds, burrowing rabbits or plant roots break bits of the rock away
what are the four types of mass movement?
-rockfall
-landslide
-mudflow
-rotational slip/slump
what is a rockfall?
individual fragments or chunks of rock fall off a cliff face often as a result of freeze-thaw weathering
what is a landslide?
sliding blocks of rock moving rapidly downslope along a linear shear-plane usually lubricated by water.
what is a mudflow?
saturated mineral (usually clay) flowing downhill which may also involve elements of sliding or slumping
what is a rotational slip/slum?
slumping of loose material often along a curved surface lubricated by water
name the 4 types of coastal erosion
-hydraulic action
-abrasion
-solution
-attrition
what is hydraulic action?
the power of the waves forcing air into cracks in the cliffside
what is abrasion?
the waves throwing material at the cliffside and acting like sandpaper
what is solution?
the dissolving of soluble rocks such as chalk
what is attrition?
pebbles in the waves collide with each other making them rounder
name 4 types of coastal transportation
-traction
-saltation
-suspension
-solution
what is traction?
large particles rolling along the sea bed
what is saltation?
a bouncing or hopping motion along the sea bed by pebbles too heavy to suspend
what is suspension?
particles suspended and carried in the water
what is solution? (transportation)
chemicals travelling dissolved in the water
what is coastal deposition?
where sediment carried by the sea is dropped and left behind.
give 4 places where deposition often takes place
-in bays
-areas shetered by bars and spits
-places with constructive waves
-near rapidly eroding cliffs
give examples of both resistant and less resistant rocks
resistant:
-granite
-limestone
less resistant rocks:
-clays
-sands
what do resistant rocks/less resistant rocks form?
resistant = headlands
less resistant = bays
what is a concordant coastline?
where the rocks are parallel to the coast forming more or less a straight line
what is a discordant coastline?
where the rocks reach the coast at right angle creating headlands and bays.
headlands are exposed to ….. ….. … so are likely to exhibit signs of ……. like …. …. ……. and …..
exposed to high energy waves so are more likely to exhibit signs of erosion like wave cut platforms and stacks.