Landforms Of Deposition

Question 1

How are beaches formed

Answer 1

Accumulations of Material deposited between low spring tides and hwm. Form when constructive waves deposit sediment on the score

Question 2

What is beach profile

Answer 2

Cross section of a beach between hwm and lwm. Determined by sediment size and wave type

Question 3

How does sediment size affect beach profile

Answer 3

• shingle beaches are steeper and narrower than sand beaches. Shingle has a higher percolation rate than sand as it is coarser. As swash from a breaking wave pushes shingle up the beach, percolation results in a loss of power. As a result there is little or no backwash to drag shingle seawards. Therefore shingle is moved in only one direction. Outcome is a beach with steep angle ~10°
• sand beaches become compact allowing little percolation. Therefore most swash returns as backwash the outcome is a beach with a lower slope angle. Sand beaches are formed from smaller particles they are wide and flat

Question 4

How does wave type affect beach profile

Answer 4

• High energy waves produce flat, wide beaches. These waves have a powerful backwash and erode sand and shingle. The sediments are transferred offshore they form a longshore bar.
• low energy waves cause a net onshore transfer of sediments where beaches become steep with prominent beach faces and ridges

Question 5

Swash aligned beaches

Answer 5

• parallel to incoming wave crest
• minimal longshore drift
• irregular coastlines where longshore drift is impeded and waves hit sections of coast head on

Question 6

Drift aligned beaches

Answer 6

• parallel to direction of dominant lsd
• large amounts of sediment transported long distances along them
• develop in regular sections of coastline
• can extend out from coastline if there is a sudden change in direction of coastline

Question 7

How are storm beaches formed

Answer 7

Strong swash at spring high tide level creates a storm beach. This is a drive composed of the biggest boulders thrown by largest waves

Question 8

How are ripples formed

Answer 8

Wave action or tidal currents

Question 9

Berms

Answer 9

Ridges of sand and pebbles (~1-2 m high) found at hwm. Formed by deposition of coarse material at the limit of the swash

Question 10

Runnels

Answer 10

grooves in the sand running parallel to the shore. Formed by backwash draining back into the sea. Separated by low ridges and are filled with water at high tide

Question 11

Cusps

Answer 11

crescent shaped indentations that form on a mix of sand/shingle beaches. develop in areas where waves break parallel to the beach and where there is a large tidal range

Question 12

Spit

Answer 12

narrow piece of land which has one end joined to the mainland and the other projecting out to sea.

Question 13

How is a spit formed

Answer 13

1. composed of sand and shingle, depends on wave energy and availability of materials
2. longshore drift occurs and the coastline changes direction or there is an estuary
3. more sheltered water
4. as the feature begins to project, storms build material above the high watermark, giving greater permanence.
5. finer materials carried further by longshore drift.
6. distal end curves due to wave refraction and second most dominant wind

Question 14

bar

Answer 14

when a spit joins 2 headlands together
can occur across a bay or rivermouth
lagoon forms behind a bar

Question 15

tombolo

Answer 15

beach that extends outward to join with an offshore island (chesil beach, dorset)

Question 16

barrier island

Answer 16

elongated bank of deposited sand or shingle lying parallel to the coastline not submerged by incoming tides.