Coasts Flashcards

Question

What is indicative of a low energy coast? | -in the Uk where do these tend to be?

Answer 1

Sandy and estuarine coasts - stretches of the coast where the waves are less powerful, or where the waves are sheltered from large waves (e.g bays of Lincolnshire) - where the rate of deposition exceeds the rate of erosion

Answer 2

- beaches - spits - coastal plains

Answer 3

Energy to be concentrated on headlands and dissipated at bays

Answer 4

``` At headlands -cliffs -stacks In bays -depositional features- beaches ```

Answer 5

Variations in rock strength lead to the formation of headlands and bays This causes wave refraction which in turn encourages erosion of the headlands and deposition in the bays-working against the erosion of the softer rock that formed the bay originally -if conditions remained stable for a long period of time a state of equilibrium would be reached where the shape of the coastline remains static due to a balance between the potential erodibility of the rocks and the effect of wave refraction.

Answer 6

- rivers (this will be deposited in river mouths and estuaries where it will be reworked by waves, tides and currents) - cliff erosion - longshore drift (sediment is transported from one stretch of coastline (as an output) to another stretch of coastline (as an input) - wind (wind-blown sand can be deposited in coastal regions). Sand dunes are semi-dynamic features at the coast that represent both accumulations (sinks) of sand and potential sources - glaciers (in Alaska ice shelves carve depositing sediment trapped within the ice ) - offshore (storm surges can be responsible for input of sediment into the coastal system)

Answer 7

A stretch of coastline, usually bordered by two prominent headlands, where the movement of sediment is more or less contained

Answer 8

These are derived from the river, coastal erosion and offshore sources such as banks or bars

Answer 9

These involve longshore (littoral) drift together with onshore and offshore processes such as rip currents

Answer 10

These include the beach, sand dunes and offshore deposits (bands and bars)

Answer 11

Where erosion and deposition are balanced? - a surge in river discharge following floods introducing vast amount of sediment into the system - an extreme storm may erode transport and transfer sediment out of the system

Answer 12

The breakdown or disintegration of rock in situ

Answer 13

The breakup of rocks without any chemical changes taking place

Answer 14

- Freeze thaw weathering (chalk is the main rock affected) - Salt crystallisation (when salt water evaporates, it leaves salt crystals behind. These can grow over time and exert stresses in the rocks. Salt can also corrode rock, particularly if it contains traces of iron - wetting and drying (rocks such as clay expand when they get wet and contract as they dry. This can cause then to crack and break up)

Answer 15

The breakdown of rocks by organic activity.

Answer 16

- thin plants roots grow into small cracks in a cliff face. These cracks widen as the roots grow which breaks up the rock - water running through decaying vegetation becomes acidic, which leads to increased chemical weathering - birds (e.g puffins and sand martins and animals (rabbits) dig burrows into cliffs - marine organisms are also capable of burrowing into rocks (piddocks) or of secreting aids (e.g limpets)

Answer 17

Involves a chemical reaction where salts may be dissolved or a clay-like deposit may result which is then easily eroded.

Answer 18

- Carbonation (rainwater absorbs carbon dioxide from the air to form a weak carbonic acid. The reacts with calcium carbonate in rocks, such as limestone and chalk, to form calcium bicarbonate which is easily dissolved. The cooler the temperature of the rainwater the more carbon dioxide is absorbed. So carbonation is more effective in winter - Oxidation (the reaction of rock minerals with oxygen e.g iron forms a rusty red power - Solution (the dissolving of rock minerals such as rock mi eras, such as halite (rock salt)

Answer 19

The downhill movement of material under the influence of gravity

Answer 20

Feb 2014- the Jurassic coast near Lyme regis in Dorset was affected by a number of dramatic landslips, damaging holiday chalets. The exposed stretch of the coastline is constantly being reshaped.

Answer 21

- creep - flow - slide - fall

Answer 22

- an extremely slow form of movement of individual soil particles downhill - often involves particles rising towards the ground surface due to wetting or freezing and then returning veritically to the surface in response to gravity as the soil dries out or thaws. This zig zag movement is similar to the of longshore drift

Answer 23

- a block of rock moving very rapidly downhill along a planar surface, often a bedding plane that is roughly parallel to the ground surface. Unlike a mudflow where the moving material becomes mixed, the moving block of material in landslide remains largely intact - frequently triggered by earthquakes or very heavy rainfall when the slip surface becomes lubricated and friction is reduced. - tend to be a considerable threat to people and property.

Answer 24

A mudflow involves earth and mud flowing downhill, usually over unconsolidated or weak bedrock such as clay, often after heavy rainfall. Water gets trapped within the rock, increasing pore water pressure, which forces rock particles apart and leads to slope failure. Pore water pressure is a form of energy within the slope system and is an extremely important factor in determining slope instability. Mudflows are often sudden and fast flowing

Answer 25

A rockfall involves the sudden collapse or breaking away of individual rock fragments at a cliff face. Often triggered by mechanical weathering or an earthquake. Once broken away from the source the rocks fall or bounce down the slope to form scree at the foot of a slope. Scree often forms a temporary store within the coastal system, with material gradually being moved and transported elsewhere by the store. The scree forms an impute to the sediment cell

Answer 26

When overland flow occurs down a slope or cliff face, small particles are moved downslope to enter the littoral zone, potentially forming an input to the sediment cell. Runoff transfers both water and sediment. Toxic chemicals can contaminate storm water and cause threats to coastal ecosystems

Answer 27

Specific to cold periglacial environments In the summer the surface layer of soil thaws out and becomes extremely saturated because it lies on top of impermeable frozen ground. Known as the active layer, this sodden soil with its blanket of vegetation slowly moves downhill by a combination of heave and flow. Solifluction characteristically formed features called solifluction lobes.

Answer 28

- Its slide surface is curved rather than flat - commonly occur in weak and unconsolidated clays and sands often when permeable rock overlies impermeable rock which causes a build up of poe water pressure.

Answer 29

When a wave advances air can be trapped and compressed. When the wave retreats the compressed air expands. This continuous process can weaken joints and cracks in the cliff, causing pieces of rock to break off. Simultaneously, bubbles formed in the water may implode under high pressure. This generates tiny jets of water which will over time will erode the rock. This process is specifically termed cavitation.

Answer 30

The action of waves breaking against unconsolidated material such as sands and gravels. Waves scoop out the loose material in a similar way to the action of a giant digger in the quarry on land

Answer 31

When waves advance they pick up sand and pebbles from the seabed, a temporary store. When they break at the base of a cliff, the transported material is hurled at the base of a cliff, the transported material is hurled at the cliff foot-chipping away at the rock.

Answer 32

Weak acids in seawater can dissolve alkaline rock (e.g chalk) or the alkaline cement that bonds rock particles together. This is solution

Answer 33

The gradual wearing down of rock particles by impact and abrasion, as the pieces of rock are moved by waves, tides and currents. This process gradually makes stones rounder and smoother.

Answer 34

-waves most erosion happens during winter storms (e.g dawlish in 2014 when destructive waves are at their largest) -rock type (lithology) physical strength and chemistry. Tough and resistant rocks such as granite erode at slower rates compared to weaker clays and shales. -Geological structure e.g cracks joints -Presence of absence of a beach beaches absorb wave energy and reduce the impact of waves on a cliff -subaerial processes weathering and mass movement will weaken cliffs -coastal management e.g groynes

Answer 35

The rolling of coarse sediment along the saa bed that is too heavy to be picked up and carried by the sea

Answer 36

Sediment 'bounced' along the seabed, light enough to be picked up or dislodged but too heavy to remain within the flow of the water

Answer 37

Smaller, lighter sediment picked up and carried within the flow of water

Answer 38

Dissolved load- chemicals dissolved in the water, transported and precipitated elsewhere.Plays an important role in the carbon cycle, transferring and redepositing carbon in the oceans.

Answer 39

Tend to form in low energy environments such as bays that are affected by waves roughly parallel to the shore

Answer 40

Form where the waves approach the coast at an angle.. Longshore drift moves sediment along the beach, often cumulating in the shape of a spit, a sediment sink or store. Sediment may be graded along a drift aligned beach. Finer shingle particles are likely to be carried further by longshore drift and and also to become increasingly rounded as they move.

Answer 41

A long narrow feature made of and or shingle, that extends from the land into the sea. Spits form on drift aligned beaches. Sand or shingle is moved along the coast by longshore drift, but if the coastline suddenly changes direction, sediment begins to build up across the estuary mouth and a spit will form. . The end of the spit will also begin to curve round as wave refraction carries material round into the more sheltered water behind the spit. A 'compound spit' occurs where the transport processes are variable over time which produces a series of 'barbs along the spit'

Answer 42

A beach that has formed between a small island and the mainland. Deposition occurs where waves lose their lose their energy and the tombolo begins to build up. Tombolo's may be covered at high tide

Answer 43

Submerged ridges of sand or course sediment created by waves offshore from the coast. Destructive waves erode sand from the beach with their strong backwash and deposit it offshore. Offshore bars act as both sediment sinks and sediment input stores. They can absorb wave energy thereby reducing the impacts of waves on the coastline.

Answer 44

- where the rock is strong and resistant to erosion, such as most igneous and metamorphous rocks - sedimentary rocks that are dipping steeply or even vertically tend to produce steep and dramatic cliffs, as with the absence of a beach and exposed orientation with a long fetch and high energy waves that encourage erosion and undercutting by the sea

Answer 45

- weak or unconsolidated rocks that are prone to slumping - rocks that are dipping towards the sea also tend to have low-angle cliffs - a sheltered location with low energy waves and a short fetch will result in subaerial debris building up at the foot if a cliff, reducing its overall angle - a wide beach will absorb wave energy preventing significant undercutting and steepening

Answer 46

-the balance of marine factors: e.g *wave energy *fetch *presence of a beach -terrestrial factors such as sub-aerial processes: *rock strength *geology The most rapidly retreating retreating beaches seem to be composed of very weak rock such as the glacial till cliffs of the Holderness coast

Answer 47

- Strata - Bedding planes - Joints - Folds - Dip

Answer 48

Layers of rock

Answer 49

Horizontal, natural breaks in the strata, caused by gaps in time during periods of rock rock formation

Answer 50

Vertical fractures caused either by contraction as sedimentary dry out or by earth movements during uplift

Answer 51

Formed by pressure during tectonic activity, which makes rocks buckle and crumple (e.g the Lulworth crumple)

Answer 52

Formed when the stress or pressure to which a rock is subjected, exceeds it's internal strength (causing it to fracture). The faults then slip or move along fault planes

Answer 53

Refers to the angle at which rock strata lie (horizontally, vertically, dipping towards the sea, or dipping inland)

Answer 54

As constructive waves will carry a range of sediment sizes up a beach due to the strong backwash, but due to the water percolating in the beach, the weaker backwash will only be able to drag back the smaller pebbles. Over time this leads to the pebbles being sorted with large at the top to smaller at the bottom

Answer 55

Due to the constant action of the waves causing abrasion and attrition

Answer 56

Due to scree falling off a cliff face

Answer 57

- Sediment is dragged offshore by destructive waves in winter - Sediment is returned by constructive waves in summer

Answer 58

- as waves are more constructive than destructive - constructive waves are less frequent and have a longer wavelength per minute, so wave energy dissipates and deposits over a wide area (weakening the backwash)

Answer 59

6-9 per minute

Answer 60

- in winter destructive waves occur at a higher frequency - Berms may be eroded by plunging waves and high energy swash crashing down onto the beach - strong backwash transports sediment offshore (depositing it as offshore bars) - sometimes the backwash exerts a rip current, or undertow, dragging sediment back as the next wave arrives over the top

Answer 61

11 to 16 per minute

Answer 62

Where a beach or spit extends across a bay to join two headlands, it forms a barrier beach or bar

Answer 63

Following rising sea levels after the last glacial period

Answer 64

- along the coast of the Netherlands | - In North America along the South Texas coast

Answer 65

- large quantities of available sand, washed onshore by constructive waves (an offshore sand bar is an ideal source of sand) - large tidal range, creating a large exposure of sand that can dry out at low tide - dominant onshore winds, that will blow dried sand to the back of the beach

Answer 66

Where sand is initially trapped by debris towards the bark of the beach

Answer 67

- dunes develop (due to sand being trapped by debris towards the back of the beach) - vegetation helps to stabilise the sand and eventually dunes develop - over a period of several hundred years a transformation occurs known as vegetation succession

Answer 68

-pioneer species

Answer 69

- Plants such as sea rocket and couch grass are able to cope with very dry, salty and exposed conditions - when they die, the plants add important organic matter to the developing soil

Answer 70

Low sand dunes, formed when pioneer plants bind the sand

Answer 71

Marram grass

Answer 72

- with long tap roots to seek water | - the growth of marram grass is stimulated by burial and its tangle of lateral roots is perfect for binding sand

Answer 73

- as the environment changes over time, different species colonise the sand dunes until they become stable - the final community will be adjusted to the climatic conditions of the area

Answer 74

Areas of flat, silty sediments that accumulate around estuaries or lagoons

Answer 75

1. ) In sheltered areas where deposition occurs (e.g in the lee of a spit) 2. ) Where salt and freshwater meet (e.g estuaries) 3. ) Where there are no strong tides or currents to prevent sediment deposition and accumulation

Answer 76

1. ) As mudflats develop, salt-tolerant plants (such as eelgrass) begin to colonise and stabilise them 2. )Halophytes (salt-tolerant species) such as glasswort and cordgrass help to stop tidal flow and trap more mud and silt 3. ) As sediment accumulates the surface becomes drier. Different plants begin to colonise (such as sea asters and meadow grass) 4. )Creeks (created by water flowing across the estuary a low tide) divide up the salt marsh

Answer 77

- To begin with, mud is deposited close to a high tide line dropping out of the water by a process known as flocculation - This involves the tiny individual particles of clay (mud) such that their combines mass enables them to sink in the seabed

Answer 78

- As with sand dunes, pioneer plants such as eelgrass and cordgrass start to colonise the transition zone between high and low tide - These plants can tolerate inundation by salty water and they also help to trap further deposits of mud

Answer 79

Gradually the mud levels rise above high tide and a lower salt marsh develops with a wider range of plants that no longer need to be adapted to salty conditions

Answer 80

Soil conditions improve and the vegetation succession begins to form a meadow

Answer 81

Eventually, shrubs and trees will colonise the area as the succession reaches its climatic climax

Answer 82

- eustatic change | - isostatic change

Answer 83

When the land rises or falls, relative to the sea

Answer 84

When the sea itself rises or falls

Answer 85

- global - in cold glacial periods, precipitation falls as snow (rather than rain) and forms huge ice sheets that store water that is usually held in the oceans - as a result sea levels fall. As temperatures rise at the end of glacial periods, the ice sheets begin to melt and retreat. - their stored water then flows into the rivers and sea, and sea levels rise

Answer 86

- local - during glacial periods, the enormous weight of the ice sheets (which can be several kilometres thick) make the land sink: isostatic subsidence - as the ice begins to melt at the end of the glacial period , the reduced weight of the ice causes the land to readjust and rise: isostatic recovery

Answer 87

- lands in the north and west (which was covered by ice sheets during the ice age ) is still rising as a result of isostatic recovery - lands in the south and east (which the ice sheets never covered) is sinking. Rivers pour water and sediment into the thames estuary and the English Chanel. The weight of this sediment causes the crust to sink and relative sea levels to rise. Therefore south-east England faces increased flood risks, not only as a result of isostatic change but also as a result of rising sea levels as a result of rising sea levels caused by global warming

Answer 88

1. )the uplift of mountain ranges and coastal land at destructive and collision plate margins that resulted in a relative fall in sea levels in some parts of the world 2. )local tilting of land at destructive margins e.g some ancient mediterranean ports have been submerged and others have been stranded above the current sea level

Answer 89

Where a fall in sea level exposes land previously covered by the sea

Answer 90

Where a rise in sea level floods the coast

Answer 91

Raised beaches

Answer 92

As the land rose as a result of isostatic recovery, former wave-cut platforms and their beaches were raised above sea level

Answer 93

On the west coast of Scotland , where remains of eroded cliff lines (called relic cliffs) can often be found behind the raised beach, with wave-cut notches and caves as evidence of past marine erosion

Answer 94

1. ) Rias | 2. ) Fjords

Answer 95

When valleys in a dissected upland area are flooded

Answer 96

In south-west England, where sea levels rose after the last ice age, the lower parts of many rivers and tributaries were drowned to form rias

Answer 97

The Kingsbridge estuary in Devon- it provides a natural harbour with the deepest water at it's mouth

Answer 98

Sheltered winding inlets with irregular shorelines

Answer 99

When deep glacial troughs are flooded by a rise in sea level

Answer 100

They are long and steep sided with a U-shaped cross section and hanging valleys

Answer 101

They are much deeper inland than they are at the coast-the shallower entrance marks where the glacier left the valley

Answer 102

Norway, Chile and New Zealand

Answer 103

Distinctive submergent coasts that form in a landscape of ridges and valleys running parallel to the coast

Answer 104

When the sea levels rise, the valleys flood, although the tops of the ridges still remain exposed, forming a series of islands running parallel to the coast

Answer 105

The Dalmatian coast in Croatia

Answer 106

According to the IPCC sea levels stabilised about 3000 years ago and they have changed very little since that time until very recently

Answer 107

About 1.7mm a year

Answer 108

Between 30cm and 1m from current levels

Answer 109

By an average of 0.85 degrees

Answer 110

- the thermal expansion of water - due to heating - the melting of freshwater ice such as the Greenland and Antarctic ice sheets and mountain glaciers

Answer 111

- tangible | - intangible

Answer 112

Where costs and benefits are known and can be given monetary value (e.g building costs)

Answer 113

Where costs may be difficult to assess but are important (e.g the visual impact of revetment)

Answer 114

- work with natural processes to build up beach which inc. tourist potential and protects land behind it - not too expensive

Answer 115

- starve beaches further along the coast of fresh sediment (because they interrupt LSD) often leading to inc. erosion elsewhere - unnatural and can be unattractive

Answer 116

£5,000 to £10,000 each (at 200 metre intervals)

Answer 117

- effective prevention of erosion | - they often have a promenade for people to walk along

Answer 118

- they reflect wave energy rather than absorbing it - they can be intrusive and unnatural looking - they are very expensive to build and maintain

Answer 119

- often used for recreation e.g fishing, sunbathing | - relatively cheap and easy to construct and maintain

Answer 120

- can be intrusive - the rocks are usually not local and can look out of place with local geology - can be dangerous for people clambering over them

Answer 121

£100,000 to £300,000 per 100m

Answer 122

Sloping wooden concrete or rock structures placed at the foot of a cliff or top of a beach. They break up the waves energy

Answer 123

They are relatively inexpensive to build

Answer 124

- intrusive and very unnatural looking | - they need high levels of maintenance

Answer 125

up to £4,500/m

Answer 126

A partly submerged rock barrier, designed to break up the waves before they reach the coast

Answer 127

An effective permeable barrier

Answer 128

Visually unappealing and a potential navigation hazard

Answer 129

Similar to rock armour-depending on the materials used

Answer 130

- relatively cheap and easy to maintain - it looks natural and blends in with the existing beach - it inc. tourist potential by creating a bigger beach

Answer 131

-needs constant maintenance because of the natural processes of erosion and LSD

Answer 132

£300,000/100m

Answer 133

- cliff regrading reduces the angle of a beach to help stabilise it - drainage removes water to prevent landslides and slumping

Answer 134

- drainage is cost-effective | - can be effective on clay or loose rock where other methods will not work

Answer 135

- regrading effectively causes the cliff to retreat | - drained cliffs can lead to collapse (rock falls)

Answer 136

Cost is variable

Answer 137

- Marram grass can be planted to stabilise the dunes | - Areas can be fenced in to keep people of newly planted areas

Answer 138

- maintains a natural coastal environment - provides important wildlife habitats - relatively cheap and sustainable

Answer 139

- time consuming to plant marram grass | - people may respond negatively to being kept off certain areas

Answer 140

£200 to £2000 per 100m

Answer 141

- relatively cheap (land reverts back to it's original state before management) - creates a natural buffer to powerful waves - creates an important wildlife habitat

Answer 142

- agricultural land is lost | - farmers or landowners need to be compensated

Answer 143

The natural processes, human activities and management decisions

Answer 144

Extremely detailed, comprehensive documents and are based on the sediment cell principle that intervention will be largely self-contained within each cell, having no knock on effects elsewhere

Answer 145

A 'closed cell'

Answer 146

1. ) Hold the line-maintaining the current position of the coastline (often using hard-engineering strategies) 2. ) Advance the line- extending the coastline out to sea (by encouraging the build up of a wider beach, using beach nourishment methods and groin construction) 3. )Managed retreat/strategic realignment- allowing the coast to retreat in a managed way (e.g creating salt marsh environments by deliberately breaching flood banks that protect low-quality farmland) 4. )Do nothing/no active intervention- letting nature take it's course and allowing the sea to erode cliffs and flood low lying land and allowing existing defences to collapse

Answer 147

The process that brings together all of those involved in the development, management and use of the coast

Answer 148

To establish sustainable levels of economic and social activity; resolve environmental, social and economic challenges and conflicts; and protect the coastal environment

Answer 149

- That complete sections of the coast are being managed as a whole rather than by individual towns or villages - This is because human actions in one place affect other places further along the coast - Essentially this is because of the transfers (flows) within the sediment cell, moving sediment from one place to another - What is eroded from one location eventually becomes a protected beach somewhere else

Answer 150

- In 2013 the EU adopted an initiative on Maritime spatial planning and Integrated coastal management - It stated that 'integrated coastal management aims for the coordinated application on the different policies affecting the coastal zone and related to activities such as nature protection, aquaculture, fisheries, agriculture industry and tourism - It will contribute to sustainable development of coastal zones by the application of the approach that respects the limits of natural resources and ecosystems, the so called 'eco-system-based approach'

Coasts Flashcards

(177 cards)