Coasts Flashcards

Question

What are terrestrial forms of sediment

Answer 1

Rivers are a major source of sediment inout to the coastal sediment budget

Answer 2

Erosion carried out by water ice wind

Answer 3

Decay and disintegration of rock in situ Mechanical weathering- freeze-thaw, salt crystallisation, wetting and drying Biological - root action Chemical weathering - carbonation

Answer 4

``` Soil creep Earth flow Landslides mudflows Slumps Rockfalls Run-off ```

Answer 5

Constructive waves, tides and currents bring sediment to the shore from offshore Wind can blow sand from other locations

Answer 6

When a coastal budget is in deficit, beach nourishment is one way a sediment equilibrium can be maintained

Answer 7

Abrasion - when waves armed with rock particles scour the coastline Attrition - when rock particles collide with each other during transportation Hydraulic action - when waves brake against a cliff face, air and water are forced into crevices. when the wave recedes the pressure is released leading to expansion of the air Pounding - the mass of the braking wave exerts pressure on the rock causing it to weaken Solution - dissolving minerals like magnesium carbonate minerals in coastal rock

Answer 8

Solution - minerals which have been dissolved into the mass of moving water Suspension - small particles of sand, silt and clay can be carried by currents Saltation - series of irregular movements of material which is too heavy to be carried continuously by suspension Traction - the largest particles are pushed along the sea floor

Answer 9

Where the rate of sediment accumulation exceeds the rate of removal When waves slow down immediately after braking At the top of swash During the backwash where water percolates in to the beach material in low-energy environment

Answer 10

When destructive waves break repeatedly on relative steeply sloping coastlines Undercutting occurs between HWM and LWM Forming a wave cut notch Continued undercutting weakens support of the rock strata above This eventually collapses Producing a step profile and a cliff Cliff retreated parallel to the coast

Answer 11

Often deeply directed by abrasion our to the large amount of rock debris that is dragged across the surface Reach a maximum length of 500M

Answer 12

Form due to the bands of rock with differing resistance to erosion These bands of rocks will be perpendicular to the coastline The width of the bay is determined by the width of the weaker rock

Answer 13

Rocks are lying parallel to the coastline

Answer 14

The waves is slowed down by the shallow water of the headland The waves in the bay speed up as they are not slowed down Waves refract around the headland

Answer 15

Geo are narrow steep-sided inlets, weak points are eroded more rapidly by hydraulic action, they form a tunnel like cave running at right angles to the cliff line Blowhole is when part of the roof of a tunnel like cave collapses and forms a vertical shaft that reaches the cliff top

Answer 16

Cracks at the base of a headland become exposed through hydraulic action, the crack widens, other processes such as salt crystallisation widen it eventually becoming a wave cut notch, more weathering becomes a cave, as a result of wave refraction the waves concentrate their energy on the sides, a hole all the way through is eventually made forming an arch, over time this becomes unstable and collapses under its own weight and forms a stack, eventually due to further weathering the stack collapses forming an arch

Answer 17

``` Less than 5 degrees Small particles means it becomes compact when wet Little percolation during backwash Little energy lost to friction material is carried back down the beach Forming ridges and runnels ```

Answer 18

Mix of pebbles and small to medium cobbles | Steeper beaches due to swash greater than backwash

Answer 19

At the back of the beach, Very strong swash during storm conditions may deposit larger material, forming a storm beach or a ridge

Answer 20

Small ridges that develop at the position of the mean high tide mark resulting from deposition at the top of the swash

Answer 21

Cusps are semi-circular depressions, they are smaller and more temporary features by a collection of waves reaching the same point

Answer 22

High - energy destructive waves remove sediment offshore and create flatter beaches (summer) winter is the opposite

Answer 23

Long narrow beaches of sand or shingle that are attached to the land at one end and extend across a bay, estuary or indentation on a coastline Form as a result of LSD The end of the spit becomes recurved Behind the spit deposition will occur as wave energy is reduced Silt and mud are deposited Eventually salt tolerant plants colonise Slat marsh develops

Answer 24

Develop when a spit develops across and indentation until it joins into the land at the other end forming a brackish lagoon on the landward side

Answer 25

Beaches which connect the mainland to an offshore bar | Spit continued the grow seaward to join the mainland to an island

Answer 26

Feature of low - energy environments, vegetated areas of silt and clay Vegetation helps stabilise the sediment The higher the marsh becomes the les saline it is Flocculation is an important process Shallow gradient

Answer 27

large areas of sediment found at the mouth of rivers deposited by rivers and tidal action branching network of distributaries Overloaded with sediment, deposition in the channel occurs, this splits the channel and reduces the energy allowing further deposition, these channels are lined with levees

Answer 28

Appointed extension of coastline

Answer 29

Sufficient sediment supply is available for the delta to grow seawards

Answer 30

Distributaries build out from the coast in a branching pattern River sediment supply exceeding the rates of removal by waves and currents

Answer 31

Changes in volume of water in the global ocean stores

Answer 32

Local | relative sea level changes

Answer 33

Changes in the land Scotland is rebounding SE coast is sinking Relative changes to the sea level Scotland - sea level fall SE coast - sea level is rising

Answer 34

Milankovitch cycles Solar output Atmosphere composition

Answer 35

A decrease in global temperature leads to more precipitation falling in the form of snow Eventually this snow turns to ice and so water is stored on land As a result, there is a reduction in the amount of water in the ocean and a worldwide fall in sea level

Answer 36

108000 years ago 7 degrees cooler than today Sea level was about 83 m lower than the present day

Answer 37

25000 years ago 9 degrees cooler than today sea level was 90m lowwer

Answer 38

Landforms are shaped by wave processes during times of high sea level These become exposed when sea level falls These features are often found well inland, some distance from the present coastline

Answer 39

Are areas of former shore platforms that were left at a higher level than the present sea level they are often found a distance inland rom the present coastline

Answer 40

After they emerged they are no longer affected by wave action the continued to be altered by mass movement and weathering

Answer 41

Submerged river valleys The lowest part of the river course and the floodplains may be completely drowned The sides of the valleys and the middle and upper parts of the rivers course may still be exposed

Answer 42

Typically underlain with alluvial deposits These were buried in channels that were eroded by rivers the flowed down to the lowest sea levels during the Pleistocene glacial periods During the interglacial periods, when sea level rose further deposition would have occurred as the rivers has less surplus energy for erosion The river valleys then became infilled during the Flandrain Transgression

Answer 43

Submerged glacial valleys | They have steep cliff - like, valley sides and he water is uniformly deep - reaching over 1000 m

Coasts Flashcards

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