EQ2 Flashcards
1
Q
What creates waves
A
- Waves come from friction between the wind and sea surface
- Fetch + wind determines wave strength
- Water particles move circular in deep water
- When waves reach shallow waters, friction builds between sea bed and base of waves
- This is frictional drag
2
Q
Berms
A
- Berms are usually created by smaller waves which have less energy
- This is where smaller ridges develop at the mean high tide mark resulting from deposition at the top of swash
E.g Gulf of Salerno, SW Italy
3
Q
Runnels/Ripples
A
- Runnels are when the waves energy spreads across a wide area of beach producing ridges
- Common on shallow sandy beaches
4
Q
Cusps
A
- Cusps are semi circular depressions
- Formed by a collection of waves reaching the same point
- The sides of the cusp direct the swash into the centre of the depression producing a stronger backwash
- E.g Pensacola Beach, Florida
5
Q
Cave, arch, stack, stump
A
- A large crack is opened up by hydraulic action
- The crack grows into a cave by hydraulic action and abrasion
- The cave becomes larger
- The cave breaks through the headland forming an arch
- The arch is eroded and collapses
- A tall rock stack is formed
- The stack erodes forming a stump
6
Q
Wave cut platforms
A
- At high tide, waves will hit the base of a cliff and erode it
- Hydraulic action & abrasion will create a wave cut notch
- The wave cut notch will get deeper
- The cliff above becomes unstable & collapses
- A wave cut platform forms and this is a platform of flat rock below where the cliff used to be
7
Q
Beaches
A
- Beaches are areas of sand, pebbles and shingle formed by deposition
- Contains a variety of sediment types + sizes
- Constructive waves may form cusps and berms
- Destructive waves may form storm ridges by high tide throwing sediment at backshore
8
Q
Offshore bar
A
- An offshore bar is when a beach parallel to the coast can be seen at low tide
- Forms in shallow water where destructive waves break before reaching the beach
- Sediment is thrown forwards and backwards & builds up under water
- At high tide the offshore bar is below the sea & the beach is exposed at low tide
9
Q
Barrier beach / bar
A
- Narrow low lying strips of beaches and sand dunes parallel to the coastline
- Separated from mainland by wetland
- Chesil beach in Dorset was an offshore bar but moved towards land by rising sea levels to become a barrier beach
- Large barrier beaches form islands
10
Q
Spits
A
Spits:
- LSD moves sediments along a coastline
- Sediments reach a gap and are carried for a while in the same direction until deposited on a sea bed
- Repetition of this forms a narrow ridge of land across a bay / estuary
Recurved spit:
- As a spit grows longer, the tides and river currents & wave directions will turn the end of a spit into a hook
Double spit:
- A double spit forms when there’s local variations in LSD & a large bay with strong river currents
- Two spits may not join because a river current flows between both
11
Q
Tombolo
A
- LSD carries sediment across a gap between mainland and an island forming a narrow ridge of sand and pebbles
- May begin as a spit but once it reaches the island it’s a tombolo
12
Q
Cuspate foreland
A
- A lot lying headland
- Formed when LSD is from opposite directions
- Sediment and sand are deposited across a bay from both directions along a coast
- Two spits form
- Two spits meet and shelter the area behind them
- Further deposition increase sediment
- Salt marshes form a new area of low land
- E.g Dungeness Kent
13
Q
Physical weathering
A
Freeze thaw weathering:
- Water gets into cracks in the rock
- At night when temps decrease, water freezes
- Water freezes and expands by upto 9%
- Pressure is out on surrounding rock
- Pieces of rock fall off
Salt crystallisation:
- Evaporation of water from rock surfaces leads to crystallisation of salts
- Increase in volume = pressure on rock
- Causes rock to fracture
Thermal expansion:
- In the day temps rise and heat the rock
- Rock heats and expands
- At night temps fall and cools the rock
- The cycle of this leads to exfoliation
- This causes top layers of rock to peel away
14
Q
Chemical weathering
A
- Ocean absorbs CO2 from atmosphere
- Creates weak carbonic acid in seawater
- Calcium carbonate like limestone and chalk are vulnerable and dissolve easily
15
Q
Biological weathering
A
- Biological weathering breaks down rock by plants and animals
- Plant roots can enlarge cracks in a rock
- This grows and expands
