Coastal systems and landscapes Flashcards

Question

What is a longshore current?

Answer 1

Currents that run parallel to the shore

Answer 2

Fast moving, narrow channels of water where waves break on the beach.

Answer 3

Cold currents from the deep ocean are brought to the surface (due to wind and earth's rotation).

Answer 4

Oceans are mostly composed of warm salty water near the surface over cold, less salty water in the ocean depths. These 2 regions don't mix except in certain areas, which creates a **large slow current.**

Answer 5

-Most waves usually arrive at an angle to the shoreline, this angled approach can change the direction of wave travel. -One end of the wave hits the seabed and slows down whilst the rest of the wave continues at it's deep water speed. -As more of the wave comes into contact with the sea floor, more slows down. -As the wave slows along its length, the crest changes direction and becomes parallel to the shoreline.

Answer 6

-Wave refraction occurs when waves approach an irregular coastline they curve and distort. -As each wave nears the coast, it drags in the shallow water. -This causes the wave to become higher and steeper with a shorter wavelength. -That part of the wave in deeper water moves faster, causing the wave to bend. -Overall effect is that wave energy becomes concentrated on the headland, causing greater erosion. -Where the waves diverge, they lose power and drop sediment.

Answer 7

A strech of coastline, usually bordered by prominent headlands, where the movement of sediment is more or less contained. (Closed coastal sub-systems)

Answer 8

**Rivers**= Accounts for large majority of sediment, sediment is deposited in river mouths and esturaries where its re-worked by waves, tides etc. **Cliff erosion** = In some areas of soft rock, erosion can reach 10m a year. **LSD** = Sediment transported from other coastlines. **Wind** = In glacial or hot environments, wind-blown sand can be deposited in coastal regions (sand dunes). **Glaciers** = Chunks of ice shelves can break off into the sea and deposit sediment trapped in the ice. **Offshore** = Transferred into ocean zone by waves, currents, tides. Storm surges can also input sediment.

Answer 9

Balance between inputs and outputs of sediment in a system

Answer 10

More inputs than outputs

Answer 11

More outputs than inputs

Answer 12

**Input changes** = Volume of fluvial material deposited into coastal system + impact of human intervention (coastal defences) + rising sea levels causing increased erosion may add more sediment. **Output changes** = Human intervention (removing large amounts of sand for industrial or coastal protection use). Sea level rise can change currents and material being removed from cells.

Answer 13

-Discreet and function separately from each other. -Sediment is stored, sourced, and transferred within the cell. -Amount of sediment available to the cell is the **sediment budget**.

Answer 14

-Can interfere with processes in a sediment cell by disrupting sediment budget. -Groynes, jetties, harbour walls block movement of sediment. -Sediment input supply can also be disrupted by dams, which cut down the amount of fluvial material entering the coastal. -Protecting soft cliffs can prevent cliff fall and reduce sediment entering system.

Answer 15

Land based processes which shape the coastline. They come under the general headings of weathering and mass movement.

Answer 16

The disintegration of rocks in situ

Answer 17

Both rain and seawater contain chemcials that can react with chemical compounds in the rock, altering its structure. -*Oxidation*: Rocks containing iron compounds experience oxidation when exposed to O2 and water from the air and sea - causes disintegration. -*Carbonation*: Coastlines composed of chalk or limestone are dissolved by acidic rain and seawater.

Answer 18

Internal pressure are exerted on rock as a result of changes in the physical structure within its mass. -*Freeze thaw*: Common where temps fluctuate below freezing and there is a ready supply of water - water freezes in cracks and expands, enarging cracks. -*Exfoliation*: Rock may expand as its heated by the sun and contracts when it cools. Causes cracks to form in rock. -*Wetting and drying*: Rock alternates between wet and dry, rocks such as shale expand when wet and contract when dry, formign cracks.

Answer 19

Living organisms can contribute to the weathering of coastal rocks throught the activity of plants and animals. -**Roots of plants** can create and expand tiny fissures, seaweed can attach to rocks and weaken them during movement. -**Animals** can excavate nesting burrows in cliffs. Some marine organisms have adpated shells that enable them to drill into rock. Algae can secrete chemicles promoting solution.

Answer 20

Movement of consolidated material (rock) and unconsolidated material (clay, soil) due to gravity.

Answer 21

(Most rapid) Occurs from cliffs undercut by the sea, or on slopes affected by mechanical weathering.

Answer 22

Occur on cliffs made from softer rocks or deposited material, which slips as a result of failure in the rock when lubricated, usually following heavy rain.

Answer 23

When heavy rain washes material from the surface of a cliff over the edge and down onto the shore.

Answer 24

Heavy rain can cause large quantities of fine material to flow downhill. Here the soil becomes saturated and if excess water can't percolate, surface layers become fluid and flow downhill. Nature of flow depends on saturation.

Answer 25

Soil or rock debris moves downhill along a concave or curved plane in a rotational manner

Answer 26

(Slowest movement) Occurs when there is very slow but continuous movement of individual soil particles downhill.

Answer 27

The movement of material along the shore by wave action. It happens when waves approach the beach at an angle.

Answer 28

Large particles e.g. boulders are pushed along the seabed by water.

Answer 29

Pebble-sized particles bounce along the seabed by the force of water.

Answer 30

Small particles like silt and clay are carried along the water

Answer 31

Soluble materials dissolve in the water and are carried along.

Answer 32

(Where waves drop material they have been carrying) -Takes place where waves are low energy or where rapid erosion provides an abundant supply of material.

Answer 33

Aeolian processes refer to the transport and deposition of sediment by wind. Surface creep = Wind rolls or slides sand across surface. Saltation = Wind temporarily lifts the grains into the airflow.

Answer 34

-Energy source altering - low energy cuases deposition. -Changes in flow direction - 2 currents meeting can increase deposition. -Interruptions to flow -Increased load - New sediment without increased energy causes deposition. -Increased friction.

Answer 35

A coast where bands of different rock types run perpendicular to the coast. The differing resistance to eroison (differential erosion) leads to the formation of headlands and bays.

Answer 36

A coast where mostly one rock type runs parallel to the coast. The outer hard rock provides a protective barrier to erosion. Coves (small sheltered bay) and wave-cut platforms form.

Answer 37

Erosion focuses on area of weakness in hard rock and continues to erode through to the soft rock which erodes faster, creating a cove. Eventually rate of erosion will slow at hard rock again.

Answer 38

Different geologies in a discordant coastline mean that there is differential erosion, hard rock erodes slower, soft rock erodes faster, this creates headlands and bays.

Answer 39

1) Sea attacks base of cliff forming a wave-cut notch through abrasion, hydraulic action, quarrying. 2) Weather weakens the top of the cliff. 3) The notch increases in size causing the cliff to collaps as it has no support underneath. 4) Backwash carries the rubble towards the sea leaving behind a wave-cut platform. 5) Process repeats and the cliff continues to retreat.

Answer 40

1) Rock fractures at intertidal zone become enlarged due to hydraulic action, abrasion and solution. They are widened further by weathering processes. 2) Crevice enlarge to form caves. The larger the SA exposed to weathering and erosion processes = increase in rate of rock removed. 3) Wave refraction leads to erosion along the side of the headland forming at a very large cave. Concentration of hydraulic action on the cave roof can form blow holes when small sections of the roof collapse. 4) Caves developing on opp sides of a headland may erode deeper due to erosion until they meet and form an arch. 5) Arch roof becomes narrower as its weathered. Becomes thinner until collapses, leaving a stack. 6) Resultant stack is weathered by sub-aerial processes at its top and marine processes at its base. Reduces in height leaving a stump. 7) Stump is eventually eroded and foundations form the wave cut platform.

Answer 41

A long, narrow beach of sand or shingle with one end attached to the shore and the other end extending into the sea. Simple spit = Extends in a straight line. Compound spit = Curved spit - has a wide recurved distal end with a series of barbs.

Answer 42

1)Spits are created due to longshore drift 2)Sediment is transported by waves along a coastline 3)When the coastline changes direction the waves no longer have the energy to carry the sediment and it is deposited 4)The build up of deposited sediment out to sea, often into an estuary, is called a spit 5)The spit often has a curved end or hooks due to a secondary prevailing wind

Answer 43

Forms when a spit connects an island to the mainland or another island, usually due to wave refraction and sediment deposition in a sheltered area.

Answer 44

Forms when a spit extends across a bay, connecting two headlands and trapping a body of water behind it, creating a lagoon

Answer 45

Long, thin, sandy strech of land parallel to the ainland. Barrier island is detached from the mainland.

Answer 46

Small ridges or hills of sand at the back of a beach, above usual maximum reach of waves. Occurs when there is enough exposed sand at low tide to dry out and be blown inland.

Answer 47

-Wide, flat beach -An obstacle for sand to accumulate around -Large supply of sand -Onshore wind.

Answer 48

Sand dune ecosystem

Answer 49

The final, stable stage of ecological succession

Answer 50

Wind blows sand which is trapped on obstacle on beach: 1)**Embryo dune** - 1m high, 80% exposed sand, *Pioneer species* (prickly saltwort) 2)Fore dune - Little organic matter e.g. sand couch grass. 3)Yellow dune - 5m high. 4)Grey dune - 8-10m, organic matter, grey soil. 5)Mature dune - Climax vegetation is reached.

Answer 51

The change in species in an ecosystem over time

Answer 52

**-**Area behind spits and barrier beaches that is very sheltered, where tidal currents and river currents meet leading to lots of deposition. Salt-tolerant species colonise these sheltered, flat muddy areas. Covered at high tide and exposed at low tide Process of sediment accumulation and plant colonization creates a *positive feedback loop*, where the plants further enhance the accumulation of sediment, leading to the continuous growth of the salt marsh.

Answer 53

Inputs: Beach nourishment, cliff and dune erosion, fluvial sediment, longshore transport. Outputs: Offshore transport, humans, longshore transport, storm events.

Answer 54

Series of ridges and troughs running parallel to the coast, near the low water mark. **Formed** by deposition during backwash and runnels are formed when water runs back to ocean.

Answer 55

Small elongated ridges. Formed when waves and currents flow across loose sand which is dragged along the bottom and is piled up.

Answer 56

Series of small ridges that form near the high tide mark. Formed by sediment deposited by constructive waves.

Answer 57

Ridge found near the back of the beach composed of larger sediment. Deposited by waves during storm events.

Answer 58

Rising or falling of land mass relative to the sea resulting from the release of weight of the ice after the last ice age.

Answer 59

Variations in relative sea level resulting from changes in the amount of liquid water entering the oceans.

Answer 60

Coastlines created when there has been a relative fall in sea level.

Answer 61

Coastlines created when there has been a rise in the relative sea level.

Answer 62

Appear towards end of an ice age, occur when isostatic rebound takes place faster than a eustatic rise in sea level (land height rises faster than sea).

Answer 63

Former wave cut platforms and their beaches were raised above present sea level due to land rising from isostatic recovery .

Answer 64

Found at back of a raised beach, steep slope formed by marine erosion thats now above sea level. E.g. = Raised beach in West Isle of Arran north of drumadoon.

Answer 65

Opposite of emergent landforms, form when eustatic rise takes place faster than isostatic rebound after an ice age.

Answer 66

Drowned glacial valleys, have steep valleys and are fairly steep and narrow. -Have a u-shaped cross section and a glacial rock basin with a shallow section at the end. E.g. - Milford sound Fjord - New Zealand

Answer 67

Created by rising sea levels drowning river valleys, floodplain vanishes beneath rising waters. Only middle and upper course valleys are filled with seawater, leaving higher land dry. E.g. - Fowey estuary in cornwall

Answer 68

A type of concordant coastline, forms when sea levels rise, flooding valleys running parallel to the coast, creating elongated islands and narrow sea channels E.g. - Croation coast in Adriatic

Answer 69

Stage 1 (**Eustatic** sea level **fall**) = More water stored in ice, less returned to sea,climate gets colder. Stage 2 (**Isostatic** sea level **rise**) = Sea level rises in relation to land, weight of ice causes land surface to sink, affects only some coastlines. Stage 3 (**Eustatic** sea level **rise**) = Produces submergent features, climate warms, ice masses on land melt, floods lower parts of land. Stage 4 (**Isostatic** sea level **fall**) = Emergent features, ice melts, land rises to previous levels.

Answer 70

**Agriculture** - Different crops need different conditions, if sea levels rise low lying farm land will be lost - impacts on global trade. **Flooding** - Amplifies frequency and intensity of weather events e.g. hurricanes and floods. **Wildlife** - Sea level rise has already led to loss of 5 vegetated reef islands (Solomon islands). **Displacement of people** - Climate refugees - India, China, Bangladesh, NZ among those most at risk, Thought some pacific island nations will be complately submerged by end of 21st century, Jakarta - home to 10 mill people - dubbed fastest sinking city.

Answer 71

Structures built perpendicular (at right angles) to the shore. Sediment is trapped as it is transported by longshore drift. The beach builds up which absorbs wave energy .

Answer 72

adv = Not as expensive as other hard engineering structures, Builds up the beach which improves tourist potential. disad = Causes sediment starvation further along the coast, Can be unattractive, Need lots of maintenance to ensure sediment isn’t getting through any holes or cracks.

Answer 73

Walls with a curved or stepped surface that absorb and reflect wave energy

Answer 74

adv = Highly effective, Can have tourism benefits as walkways are created. disad = Very expensive to build and maintain - £6000 per metre, ugly and intrusive to the landscape.

Answer 75

Wire cages filled with rocks or pebbles, stacked to form a barrier along the coast. They absorb wave energy and reduce erosion, similar to rock armour.

Answer 76

adv = Flexible and can be molded to fit the contours of the coastline, relatively inexpensive and can be installed more quickly. disad = May not last as long as rock armour and can be damaged by strong waves or vandalism.

Answer 77

Large concrete or granite boulders at the foot of a cliff. The spaces in between the boulders cause waves to bounce between many surfaces, reducing the energy of the wave

Answer 78

adv = Cheaper than sea walls, Used for recreation such as fishing. disad = Dangerous when people are on them, Rocks from elsewhere are intrusive to local geology.

Answer 79

Adding sand or shingle to a beach to widen it - creates more surface area to absorb wave energy

Answer 80

adv = Looks very natural, Bigger beaches are good for tourism, Relatively inexpensive. disad = Material is constantly subject to erosion and longshore drift so lots of maintenance and monitoring are needed, Dredging the seabed can have impacts on local ecosystems.

Answer 81

Reducing the angle of the cliff to stabilise the slope. Drainage of water also stabilises the cliff against mass movement

Answer 82

adv = cost-effective disad = Can look unnatural as the cliff is unnaturally flatter, This effectively creates a cliff retreat, Dried-out cliffs can collapse.

Answer 83

This is a form of do-nothing or managed retreat. The land is allowed to be flooded by the sea and then left to become a salt marsh. This absorbs wave energy and also creates a buffer to rising sea levels and projects higher-value land.

Answer 84

adv = A cheap option, Creates important and unique wildlife habitats. disad = Agricultural land is lost which creates a need for compensation.

Answer 85

DEFRA overseas coastal management of the UK, and it was them who introduced SMPs. There are 4 policies SMPs have to decide from how a section of coastline should be managed: 1)**No active intervention** = Letting nature take its cours - chosen when cost of aid > economic benefit. 2)**Hold the line** = Maintaining current position of coastline, to reduce or stop the retreat of the coastline. 3)**Managed retreat** = Allowing coast to retreat in a managed way e.g. creating salt marsh environments. 4)**Advance the line** = Extending the coastline out to sea by encouraging the build-up of a wider beach.

Answer 86

Means complete sections of coasts are managed as a whole, rather than individual towns or villages. A key aim is to co-ordinate all potential conflicts of interest and handle them fairly e.g. following sustainable strategies, identifying stake holders, monitoring and recording of what is taking place at the coast.

Coastal systems and landscapes Flashcards

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