what type of landform in a beach?
- is a coastal depositional landform
characteristics of a sandy beach? gradient waves inland distance back of beach features on wet sand?
- gradient = flat - waves = constructive - distance inland = far - back of beach = sand dunes - at low tide, runnels (water-filled depressions? create ripples at back of beach
characteristics of a pebble beach? gradient waves inland distance back fo beach pebble size
- gradient = steep - waves = destructive - distance inland = not far - back of beach = large pebbles - pebbles increase in size towards back of beach
what is a beach profile ? (3) beach profile of a sandy and pebble beach
- shows the gradient from the back of beach to front go beach - pebble beach has a steep beach profile - sandy beach has gently, almost flat beach profile
gradient of beach at summer and winter constructive + destructive waves
- The gradient of the beach tends to change during the year. - Beaches are steeper in summer because constructive waves are more common in summer - destructive waves are more common in winter making the beach flat
what happens to berms and sand dunes at back of beach in winter?
- destructive waves are common in winter - can destroy berms / sand dunes at back of beach
what is a berm? how is it formed?
destructed in winter
sand dunes
summer
waves
- A nearly horizontal plateau on the beach face or backshore, formed by the deposition of beach material by wave action
- in winter, sand dunes and berms are eroded by destructive waves, creating an offhsore bar
- in summer, constructive waves (common in summer) will rebuild beach, sand duen are replenishd by saltation
what is offshore on beach?
what is nearshore on beach?
what is forshore on beach?
what is backshore on beach?
off shore - (waves not breaking)
nearshore (waves break)
foreshore (inter-tidal zone - repeateldly covered and then uncovered by changing low and hugh tide)
backshore (dry, not usualyy affected by waves)
what you need for sand dunes to form?
why do you need ea h characterstic?
(5)
- large sand supply
- large flat becah
- onshore wind (move sand to back of beach)
- obstacle (driftwood)
- large tidal range (time for sand dune to dry)
% of wind movement
explain each one
(3)
1% suspension - sand carried in wind
4% creep - sands collide with each other and push other grians along
95% saltation - garins bounce along in wind, alternatively raised and dropped
how do sand dunes form?
process
(6)
1) heaviest grains of sand will settle on one side of driftwood
2) lightest grains will settle on the other side
3) sadn will travel up the windward side creating a pile oof sand that will become so unstable and collapse
4) lighter grains of side will travel down on the leeward side and stop fallin until at stabel angle of 30-34 degees
5) repeated cycle of win blowing uo windeward side and down leeward side causes the dune to migrate inland over time
6) dune itself can become an obstacle and more dune can form infront or behind it.
characterstics of a sand dunes?
(3)
lee ward
wind ward side
angle
- 30-34 degrees lee ward side
- crest of sand dune height = up to 15 m
- gentle slope on windward side
how do dunes change inland?
why?
(6)
- dune closet to the sea are more yellow (mature)
- dunes away from the sea (mature dune ) are grey / less sand-like
- size increase as you go inland (marram grass bind sand together, preventing further migration, grass makes sand accumulate)
- dunes grow taller - mature dunes are only a few m tall, mature dunes grow up to 15 m
- dunes increase in vegetation
- each dune is separated by a trough called a slack. can be eroded so much that it reached the water table resulting in salty ponds between each dune
what type of landform are spits and bars ?
landform associated with LSD
what is a spit ?
where you can have it
(3)
- sand/shingle beach that is joined to land but projects to sea
- can have one at the mouth of an estuary
how do spits form?
(4)
coastline
deposition
prevailing wind
LSD
waves
lagoon
1) coastline changes shape, waves lose energy and deposition occures at proximal end, spit projects out of land
2) prevailing wind cause LSD, moves material in a zig-zag pattern across the beach
3) is the prevailing wind changes direction, a hook is formed at end of spit at distal end
4) Waves cannot get past a spit, which creates a sheltered area where silt is deposited and mud flats or salt marshes and lagoon form.
characteristics of a spit?
ends
end of spit
features at enf of spit
size
size of pebbles
(6)
- proximal end (land where spit forms)
- hook and recure
- distal end (hook)
- lagoons, salt marshed, mudflats
- spit approx 4 km
- pebbles become increasingly smaller towards distal end
characterstics of a bay bar
what is it?
- bay bar (sand that stretches from one headland to another) due to LSD, craeting a lagoon
- bar is visible at all times
characterstics of a submerged bar
what is it ?
- a bar completely detatched from land
- form in shallow waters
characteristics of an offshore bar ?
what is an offshore bar?
- at high tide, submerged bar turns into an offhsore bar
- in winter, destructive waves drag material out of beach to sea to form offshore bar
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Erosion, Transportation, deposition9
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Gorkha, Nepal Earthquake4
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L'Aquila Earthquake12
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long profile/cross profile and details of upper, middle, lower course of river6
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hydrological cycle of a Drainage basin4
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Spits and Bars, sand dunes9
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Typhoon Haiyan7
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Reducing The Effects of Tropical Storms9
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hard and soft engineering19
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headland/bay/cliffs/wave-cut platforms/ caves12
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beaches21
