EQ2:How Do Charcteristic Coastal Landforms Contribute To Coastal Landscapes

Question 1

How is a wave created?

Answer 1

A wave is created through friction between the wind and water surface, transferring energy from the wind into the water. This generates ripples, which grow into waves when the wind is sustained.

Question 2

What’s beach morphology

Answer 2

The shape of a beach including its width/slope

Question 3

What’s a sediment profile

Answer 3

Pattern of distribution of different sizes.shaped deposited materials

Question 4

What does wave size depend on

Answer 4

the strength of the wind
the duration for which the wind blows
water depth
wave fetch

Question 5

How does a wave break?

Answer 5

1)​When waves reaching the shore reach a wave depth of 1/2 their wavelength, the internal orbital motion of water within the wave touches the sea bed.
2)Friction between the sea bed begins to distort the wave particle orbit from circular to elliptical, and slows down the wave.
3)The wave has entered the offshore zone
4)The wave depth decreases further, and the wave velocity slows, wavelength shortens, and wave height increases. Waves ‘bunch’ together.
5)The wave crest begins to move forwards much faster than the wave trough
6)Eventually the wave crest outruns the trough and the wave topples forwards - breaking.
7)The wave breaks in the nearshore zone, and water flows up the beach as swash
8)The wave then losses energy and gravity pulls the water back down the beach as backwash

Question 6

What are constructive waves?

Answer 6

-Low energy waves
-Low, flat wave height (<1m)
-Long wavelength (up to 100 m)
-Low wave frequency (about 6-9 per minute)
This means their swash is unimpeded by previous backwash
-A strong swash that pushes sediment up the beach, but a weaker backwash is unable to transport all particles back down, so they are deposited it as a ridge of sediment (berm) at the top of the beach
-A backwash that percolates into the beach material
encouraged by a long, shallow nearshore, so friction slows down the wave and releases energy
-Constructive (spilling or surging) waves have a stronger swash than backwash due to a low angle of wave impact
-results in less steeper beach profile as sediment is being pushed up the beach.

Question 7

What’s destructive waves?

Answer 7

-Weak swash and powerful backwash produces a net transport of sediment down the beach, reducing beach gradient.
-Some sediment thrown forwards in detached spray of high impact breaking wave. Accumulates above high tide mark as storm ridge.​
-Large, pebble-sized sediment dragged down beach by backwash to form wide ridge of material below low tide mark at start of offshore zone.
-Friction may be sufficient to cause backwash to down some sediment on middle or lower beach, with deposited sediment size decreasing towards sea.

Question 8

What are ridges?

Answer 8

Area of foreshore that’s raised

Question 9

What’s runnels

Answer 9

A shallow trough in foreshore

Question 10

What’s runnels

Answer 10

A shallow trough in foreshore

Question 11

What’s a berm

Answer 11

Shingle ridges formed beneath the storm beach

Question 12

What’s a storm beach?

Answer 12

Very coarse sediment deposited here during severe storms

Question 13

What are long-shore bars

Answer 13

A shore parallel bar separated from the beach by a deep trough

Question 14

What’s a cusp

Answer 14

Crescent-shaped indentations that form on beaches of mixed sand and shingle -due to wave refraction
-cusp is where fine sediment is ,bay is where the coarse sediment is

Question 15

What are daily changes that can change beach morphology and sediment profiles over time.

Answer 15

-storm season— waves get more energy,leads to formation on destructive waves which can erode landscape
-winter season-Calm anticyclonic conditions in winter can produce constructive waves that begin to rebuild beach, steepening profile for few days before storm
-Destructive waves change to constructive ones as the wind drops.
-Storm beaches, high at the back of the beach, result from high energy deposition of very coarse sediment during the most severe storms

Question 16

What are some monthly variations that can change beach morphology?

Answer 16

Tide height varies over course of lunar month, with highest high tide occurring twice a month at spring tide and two very low high tides (neap tides)​
As month progresses from spring down to neap tide, successively lower high tides may produce a series of berms at lower and lower points down the beach.
Once neap tide passes and move towards next spring tide, berms successively destroyed as material pushed further up beach by rising swash reach.

Question 17

What are some seasonal changes that can change beach morphology?

Answer 17

Destructive, high-energy waves dominate in the winter, lowering angle of beach profile and spreading shingle over the whole beach. Offshore ridges/bars formed by destructive wave erosion and subsequent deposition of sand and shingle offshore. berm-type profile
In summer, constructive, low-energy waves dominate, steepening beach angle and sorting particles by size, with larger shingle particles towards back of beach. ​​In summer, constructive waves build berm ridges, typically of gravel/shingle at high tide mark bar-type profile
Low channels and runnels between berms

Question 18

What are the four types of erosion?

Answer 18

1) Hydraulic action- air trapped in cracks and fissures is compressed by force of waves crashing against the cliff face.
2)solution/corrosion- carbonate rocks e.g. limestone is dissolved by the water
3)abrasion- sediment picked up by breaking waves is thrown against the cliff face
4)attrition- collisions between rocks

Question 19

How is abrasion influenced by wave type,size and lithology?

Answer 19

Wave Type- destructive waves to carry large sediment as they have a stronger backwash,pulling sediment away from coast + enabling repeated impacts.
Wave Size-high height and short wavelength- as they have more energy to throw heavier and larger sediment at cliff
Lithology- Loosely consolidated such as shingles/pebbles as they’re more vulnerable than hard ones.

Question 20

How is hydraulic action influenced by wave type,size and lithology?

Answer 20

Wave Type- prevalent with high energy destructive waves as they are tall and can reach higher up the cliff; when they strike the coastline, they exert significant pressure, driving air and water into cracks
Wave Type- High height and short wavelength which have more energy to widen the crack; higher waves exert greater pressure and more energy- more forceful compression of air and water
Lithology- loose clastic lithology more likely to be affected as its more vulnerable to erosion-more porous

Question 21

How is solution influenced by wave type,size and lithology?

Answer 21

Wave Type-slow constructive waves-allow more rock to be dissolved as rock have more time to be for chemical reactions to happens as they’re in the presence of sea water for a longer time
Wave Size- bigger waves - as larger waves provide more exposure to water,facilitating solution Longer wavelengths lead us to slower moving water that stays in contact with rock
Lithology- chemically weak rock such as chalk/limestone - which reacts with acidic limestone

Question 22

How is attrition influenced by wave type,size and lithology?

Answer 22

Wave Type- Destructive waves gives lots of energy to collide; cause frequent and violent collisions between rock fragments as they move them back and forth. As wave energy increases so does _ frequency and forced sediment interactions
Wave Size- high height and short wavelength as there’s more energy for forceful collisions. Short wavelength concentrate energy leading to more intense frequent sediment movement
Lithology- softer rocks -less resistant e.g. sandstone and limestone