Option B - Interactions between oceans and coastal places

Question 1

Waves : constructive waves

Answer 1

depositional waves, called ‘spilling’ or ‘swell’ waves - long wavelength low height and low frequency. High period. Greater swash than backwash

Question 1

Waves : destructive waves

Answer 1

erosional waves
‘surging’ ‘storm’ waves
short wavelength high height
low period
high frequency
backwash greater than swash

Question 2

Subaerial and wave processes

Answer 2

subaerial : surface run off , rain wash, weathering by wind and frost, mass movement (soil, creep, landslides and slumps)

Human activity: can increase run off and erosion and sea defences

corrosion: salt crystallisation disintegrated weaker layers and blue /green algae help break down rock

Biotic factors : Burrowing and browsing organisms

Abrasion /Corrasion: wearing away of cliff by material (rocks, sand) hurled against it

Currents: generates by waves /tides

Attrition : wearing down of broken materials into smaller rounder particles

Solution : dissolving of limestone and other minerals by carbonic acid in seawater

Hydraulic action : shock waves up to 30 tonnes / m*2

Hydraulic pressure : compression of trapped air and sudden release

Question 3

Salt weathering

Answer 3

process by which sodium and magnesium compounds expand in joints and cracks thereby weakening rock structures

Question 4

freeze thaw weathering

Answer 4

process whereby water freezes, expands and degrades jointed rocks

Question 5

biological weathering

Answer 5

carried out by molluscs, sponges and sea urchins, important in low energy coasts

Question 6

Tides

Answer 6

regular movements of the sea’s surface caused by the gravitational pull of the moon and the sun on the ocean. Tides are greatest in bays and funnel shaped coastlines - tidal range controls the vertical range of erosion, deposition, weathering and biological activity. Can also have a scouring effect and remove debris.

Question 7

Littoral drift

Answer 7

movement of sediment along the coastline due to prevailing winds where swash comes angular to coast and backwash goes straight

Question 8

Sediment (mass movements)

Answer 8

provide large amounts of material which may bury beaches and protect cliffs

Question 9

Rivers

Answer 9

most carry sediment (fine grained silts, clays and sands) to the coast

Question 10

Periglacial processes

Answer 10

provide frost shattering shingle for beaches

Question 11

Erosion of cliffs

Answer 11

by the sea produces large amount of material for beach building. This may protect the cliff from further erosion

Question 12

Sea

Answer 12

may transport sediments shorewards forming offshore bars and beaches

Question 13

Wind erosion

Answer 13

carries a lot of fine sand

Question 14

Volcanic activity

Answer 14

may produce ash or dust for beaches

Question 15

Cliffs

Answer 15

profile of a cliff depends on a number of factors
- geological structure
-subaerial and marine processes
-amount of undercutting
- rates or removal
- stages of development

rocks of low resistance are usually eroded and are unable to support an overhang. Jointing may determine the location of weaknesses in the rock just as the angle of dip may control the shape of the cliff

Question 16

Stacks

Answer 16

wave refraction concentrates wave enegy on the sides of the headlands. If there are lines of weakness, these may be eroded and widened - over time this may be enlarged to form caves and caves on either side of headland will form an arch. Further erosion with mean the roof collapses and the arch turns into a stack. eventually becomes stump

Question 17

Wave- Cut Platform

Answer 17

include intertidal platforms, high tide platforms and low tide platforms. Wave cut platforms are most frequently found in high energy environments and are typically less than 500 m wide

Question 18

Beaches

Answer 18

accumulation of sand or shingle in areas which are sheltered and or have a large supply of sediment. Beach form is affected by the size, shape and composition of materials, tidal range and wave characteristics. Sediment side affects beach profile through percolation rate.

Question 19

Storm Beach

Answer 19

noticeable semi-permanent ridge found at the level of the highest spring tides

Question 20

Berms

Answer 20

small scale beach ridges built up by successive levels of tides or storms

Question 21

Cusps

Answer 21

semi-circular embayments found in the shingle or at the shingle sand interface

Question 22

Spits

Answer 22

beach of sand or shingle at one end to land. For examples along a coasts where headlands and bays are common and near mouths, wave energy is reduces. They generally have a thin attached end, the proximal end and a larger distal end with smaller recurves. Spits often become curved as waves undergo refraction - cross-currents or occasional storm waves may assist

Question 23

Changing sea levels

Answer 23

sea levels change in connection with the growth and decay of ice sheets.

Question 24

Eustatic Change

Answer 24

Eustatic change refers to global change in sea level (at the height of glacial advance, 18000 years ago sea level was 100-150m below current sea level)

Question 25

Isostatic Change

Answer 25

level of the land also varies in relation to the sea. land rise may result of tectonic uplift or following the removal of an ice sheet. The localised change in the level of the land relative to the level of the sea is isostatic change or adjustment

Question 26

Sea level change

Answer 26

Temperatures decrease glaciers and ice sheets advance and sea levels fall eustatically. Ice thickness increases and the land is lowered isostatically Temperature rises ice melty and sea levels rise eustatically. Continued melting releases pressure on the land and the land rises isostatically.

Question 27

differences in sea level between places

Answer 27

eustatic global changes will not affect all places to the same degree or level

Question 28

Sea level change of the coast of Britain

Answer 28

as a result of global warming sea levels are rising impacting especially people in low lying communities

Question 29

Retreating coastlines

Answer 29

include submerges coasts and coasts where the rate of erosion exceeds the rate of emergence

Question 30

Advancing coastlines

Answer 30

emerged coastlines and coasts where deposition is rapid

Question 31

Advancing and Retreating coastlines

Answer 31

result from sea level changes and from erosion and deposition. Point A and X both experienced uplift around 100m but erosion has taken place at A.

Question 32

Features of emerged coastlines

Answer 32

Raised beaches Coastal plains relict cliffs raised mudflats

Question 33

Submerged coastlines

Answer 33

rias - drowned river valleys caused by rising sea levels / sinking of the land fjords- drowning of U-shaped valleys Fjards - drowned glacial lowlands

Question 34

Sand Dune development

Answer 34

1) as the tide goes out the sand dries and is blown up the beach. At top of the beach is line of seaweed and litter (strand line). Small embryo dune forms in shelter behind strand line. 2) sea couch grass colonizes and helps bind the sand. Once the dune grows over 1 m high, marram grass replaces the sea couch - yellow dune formed at 10-20 m high 3) once the yellow dune is over 10m high less sand builds up behind it and marram grass dies to form humus layer. As soil begins to form, other plants are able to grow eg dandelions. Semi fixed dune develops 5) fixed dune : as time goes on and soil develops plants become richer and damper - lichen mosses and flowering plants can grow on the dune and form continous cover over the sand. Marram grass replaced by red fescue grass 5)as the dune system gets older - water can collect towards back of dune and allows marsh plants and small willow trees to grow 6) climax vegetation succeeds grasses and flowering plants as small trees mature