3.3(Spec2) - Deposition + Distinctive Landforms

Question 1

How are offshore bars made?

Answer 1

• made from deposition of sediment carried back from coast by backwash

Question 2

How are double spits formed?

Answer 2

• LSD occurs in opposing directions on 2 headlands of bay
• join together

Question 3

How are recurred spits made?

Answer 3

• water depth may become more shallow, resulting in more deposition
• waves may come in a secondary direction due to different wind directions

Question 4

How are swash aligned beaches made?

Answer 4

• swash and backwash in a bay come in at 90º
• wave energy is focussed on headlands (wave refraction causes waves to come in at 90º)
• erosion focussed on headland

Question 5

When does deposition occur?

Answer 5

• Interference: transport of material is stopped (wind/river)
• wave refraction: energy of waves decreases in bay (can also change direction of sediment transport within bays if there are obstructions eg. Piers)
• Distance decay/Gravity settling: wave energy decreases

Question 6

What is marine transgression?

Answer 6

• Shoreline rises due to sea level rise relative to land

Question 7

What is a bayhead beach?

Answer 7

• swash aligned beach
• wave refraction means erosion occurs at headland
  
  • deposition in bays

Question 8

What is an example of a bayhead beach?

Answer 8

Lulworth Cove, Dorset

Question 9

What is a tombolo?

Answer 9

• sand/shingle bar that attaches coastline to an offshore island

Question 10

What is an example of a tombolo?

Answer 10

St Ninian’s tombolo, Shetlands (Scotland)

Question 11

What are types of distinctive coastal landforms?

Answer 11

• recurved spit
• bayhead beaches
• spits
• tombolo
• bar
• offshore bar

Question 12

What is a drift aligned coastline?

Answer 12

• coastline is at an angle to prevailing wind direction

Question 13

What can happen to sediment along a drift aligned coastline?

Answer 13

• Smaller, more rounded sediment taken further along beach
  
  • since smaller, even weaker waves can carry sediment up beach via swash

Question 14

How are tombolos created?

Answer 14

1. Drift aligned coastline: LSD builds spit out from land that joins island.
2. Swash aligned coasts: wave refraction around island occurs when waves hit island
   - results in waves losing energy and depositing sediment behind island and between shore.

Question 15

What is a swash aligned coastline?

Answer 15

• swash is parallel to coastline
  
  • results in very little LSD

Question 16

Why might deposition occur?

Answer 16

• wave refraction
• wind energy being reduced (temporary)
• resistance by obstructions (eg. groynes)
• friction with floor in shallow regions