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Buisness > 2.1 - Coastal processes > Flashcards

2.1 - Coastal processes Flashcards

1
Q

What are the zones that the littoral zone can be divided into

-name them in order

A

coast
backshore
foreshore
nearshore
offshore

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2
Q

What is the backshore zone found in the littoral zone

-what is it

A

area between the high tide mark
- affected by wave action during major storms

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3
Q

What is the foreshore zone found in the littoral zone

-what is it

A

area between high tide and low tide mark
- seen as most important area for marine activity

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4
Q

What is the nearshore zone found in the littoral zone

-what is it

A

-area of shallow water where friction occurs between seabed and waves- causing waves to break

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5
Q

What is the offshore zone found in the littoral zone

-what is it

A

area of deeper water beyond the point where waves begin to break
friction occurs between seabed and waves- could cause distortion in wave shape

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6
Q

Name the 2 main types of coastlines formed by the littoral zone

A

Rocky/ Cliffed coastlines
- Coastal plain landscapes

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7
Q

What are rocky coastlines

A

reas of high relief

resistant rock areas- resistant to erosive power of sea, wind, rain

high energy environments

rock types: igneous, sedimentary and metamorphic rocks- granite, slate, limestone

erosion is greater than deposition

destructive waves

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8
Q

What is weathering

A

chemical, bilogical, mechanical breadown of rocks into smaller fragments in situ

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9
Q

What is mass movement

A

landslides, slumps, rockfalls all of which move material downslope under the influence of gravity

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10
Q

What is surface runoff

A

water, usually during heavy rain, flowing down cliff face and causing erosion

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11
Q

What is the littoral zone

A

-boundary between land and sea

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12
Q

Why does the littoral zone vary

A

due to:
short-term factors- daily tides, seasonal storms, individual waves

long-term factors- changes to sea levels, climate change

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13
Q

Name the 3 coastal landscapes the littoral zone forms

A

rocky, cliffed coastline
sandy coastline
estuarine coastline

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14
Q

What are sandy coastlines

A

areas of low relief with sand dunes and beaches, that are much flatter

form in areas with:

less resistant geology
a low energy environment
where deposition > erosion
constructive waves

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15
Q

What are estuarine coastlines

A

areas of low relief with salt marshes and mudflats (estuaries)

form:

in river mouths
where deposition > erosion
in a low energy environment
usually in areas of less resistant rock

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16
Q

What is coastal accretion

A

deposition of sediment at the coast and the seaward growth of coastline- creating new land

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17
Q

What is dynamic equilibrium

A

balanced state of a system when inputs and outputs balance over time

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18
Q

How are coastal plains maintained in a state of dynamic equilibrium in many locations

A

deposition of sediment from river systems inland and from offshore and longshore sources

erosion by marine action

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19
Q

What is a cliff profile

A

height and angle of a cliff face as well as its features

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20
Q

Name the inputs in the coastal system

A

inputs

marine- waves, tides
atmospheric- weather/ climate
land-rock type, structure
people- human activity, coastal management

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21
Q

Breakdown the coastal system

A

-inputs -> processes -> outputs

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22
Q

Name the processes in the coastal system

A

weathering
mass movement
erosion
transport
deposition

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23
Q

Name the outputs in the coastal system

A

erosional landforms
depositional landforms
different types of coasts

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24
Q

Name the 2 ways coasts can be classified

A

longer-term criteria:

geology
sea level change
short-term criteria:

level of energy
advancing/ retreating

25
Q

How can coasts be classified by their geology

A

lithology (rock type) and structure of rocks

-used to determine if coast rocky, sandy or estuarine and concordant / discordant

26
Q

How can coasts be classified because of sea level change

A

used to classify coasts as emergent/ submergent

can be caused by:
tectonic processes- lift/ subside land- effects sea levels
climate change- sea levels rise and fall

27
Q

How can coasts be classified because of energy inputs

A

receive energy inputs form waves, tides, currents, rivers, atmospheric processes, gravity tectonics

classify coasts as high/ low energy

28
Q

How can coasts be classified because of advancing/ retreating

A

classified as advancing/ retreating due to long-term processes (emergent/submergent) and short term (outbuilding/eroding)

29
Q

What are the 2 main cliff profile types

A

marine erosion dominated (steep face)
- sub-aerial process dominated (curved slope profile)

30
Q

What factors can determine a rocks resistance to erosion and weathering

A

How reactive minerals in the rock are when exposed to chemical weathering- e.g. calcite (found in limestone) can be weathered by solution, whereas quartz (found in sandstone) is not subject to chemical weathering

if rocks are clastic/ crystalline- igneous rocks are crystalline and are more resistant, sedimentary rocks are clastic (made of cemented sediment particles

if rocks have cracks, fractures and fissures, which are weaknesses exploited by the forces of weathering and erosion

31
Q

What are primary coasts?

A

Coastlines dominated by land-based processes such as deposition

32
Q

What are secondary coasts?

A

Coastlines dominated by marine erosion or deposition processes

33
Q

What is the difference between emergent and submergent coasts?

A

Emergent - coasts rising relative to sea level (e.g. due to tectonic uplift)
Submergent - coasts being flooded by the sea (due to rising sea levels or subsiding land)

34
Q

What is dynamic equilibrium

A

balanced state of a system when inputs & outputs balance over time

-this is due to balancing forces of:
-deposition of sediment from river
-erosion by marine action at coast

35
Q

What are the 3 key elements to geological structure and what do they mean?

A

Strata - the different layers of rock within an area and how they relate to each other

Deformation - degree to which rock units have been deformed by tectonic activity

Faulting - presence of major fractures that have moved rocks from their original positions

36
Q

What are concordant and discordant coastlines?

A

Concordant - rock strata run parallel to the coastline

Discordant - different rock strata intersect the coast at an angle

37
Q

How are headlands and bays formed at discordant coastlines?

A

Softer rock eroded faster - creating bays
Wave refraction means lateral erosion occurs at headlands (cave arch stack stump), while wave energy in bays is much lower and erosion is reduced

38
Q

How do coves form on concordant coastlines?

A

More resistant rock broken through by marine erosion, and the softer rock behind is then rapidly eroded to form wide coves. At the back of the coves is more resistant rock which prevents erosion further inland

39
Q

What is a Dalmatian coastline?

Coastline made up of anticlines and synclines that has been drowned by rising sea levels, creating concordant coastline of long narrow islands arranged in long lines offshore

A

What is a Haff coastline?

A concordant coastline where long sediment ridges topped by sand dunes run parallel to the coast offshore, creating lagoons between ridges and shore

40
Q

What 2 geological factors affect cliff profiles?

A

the resistance to erosion of the rock
the dip of rock strata in relation to the coastline

41
Q

What is dip, and why is it important in determining cliff profiles?

A

Dip is the angle of rock strata in relation to the horizontal.
It is important as determines the stability of the cliff

42
Q

What are joints?

A

Joints divide rock strata up into blocks with a regular shape

43
Q

What are fissures?

A

Much smaller cracks in rocks, often only a few centimetres or millimteres long

44
Q

How does folding occur and how does it create anticlines and synclines?

A

Folding occurs due to crustal compression - when horizontal strata are ‘squeezed’ they can be folded into a series of anticlines and synclines.
Anticlines - A shaped (convex up)
Synclines - U shaped (concave down)

45
Q

What are faults?

A

Major fractures in rocks produced by tectonic forces and involving the displacement of rocks on either side of the fault line

46
Q

What is unconsolidated sediment?

A

Material such as sand, gravel, clay and silt that has not been compacted and cemented to become sedimentary rock, so is loose and easily eroded

47
Q

What is igneous rock (give examples) and what is it’s erosion rate?

A

Igneous rock is formed from the cooling and solidification of magma - e.g. granite or basalt
VERY SLOW rate of erosion (< 1mm a year) - as they are crystalline and have few joints

48
Q

What is metamorphic rock (give examples) and what is it’s erosion rate?

A

Metamorphic rocks are rocks that have become changed by intense heat or pressure while forming. e.g. slate, marble
SLOW erosion rate (1mm to 10 cm per year) - some are crystalline, others are folded and heavily fractured

49
Q

What is sedimentary rock (give examples) and what is it’s erosion rate?

A

Sedimentary rocks are formed from pre-existing rocks or pieces of once-living organisms. e.g. sandstone, limestone
MODERATE TO FAST erosion rate (10cm to several metres) - often clastic, and have many bedding planes and fractures

50
Q

What is the difference between impermeable and permeable rocks?

A

Permeable - allow water to flow through them
Impermeable - do not allow groundwater flow

51
Q

What is pore water pressure?

A

The pressure water experiences at a particular point below the water table due to the weight of water above

52
Q

How does vegetation stabilise sediment?

A

Roots of plants bind sediment particles together making them harder to erode
When submerged, plants growing in sediment providing a protective layer (surface of sediment not exposed to moving water)
Plants reduce wind speed to reduce wind erosion because of friction with vegetation

53
Q

What is the difference between halophytes and xerophytes?

A

Halophytes - tolerate salty conditions
Xerophytes - can tolerate very dry conditions

54
Q

What is a psammosere and a halosere?

A

Psammosere - sand dune ecosystem
Halosere - salt marsh ecosystem

55
Q

What are the stages in sand dune succession?

A

embryo dunes
fore dunes
yellow dunes
fixed dunes (grey)
heath/woodland

56
Q

What are the roles of embryo dune pioneer plants?

A

stabilise mobile sand with their root systems
reduce wind speeds at the sand surface, allowing more sand to be deposited
add dead organic matter to the sand, beginning the process of soil formation

57
Q

Why are sand dunes a dynamic environment?

A

periods of wind erosion can create low areas within dune systems called dune slacks
embryo and fore dunes are prone to wind and wave erosion, particularly during major storms, but the dune front will stabilise as long as the supply of sediment to the coast resumes

58
Q

Why are estuaries ideal for the development of salt marshes?

A

sheltered from strong waves so sediment can be deposited
rivers transport a supply of sediment to river mouth, which may be added to by sediment flowing into an estuary at high tide

59
Q

Q
What are the stages in salt marsh succession?

A

Algal stage - algae grows on and within bare mud, binding it together
Pioneer stage - roots begin to stabilise mud
Establishment stage - continuous carpet of vegetation established
Stabilisation - area of salt marsh rarely submerged
Climax vegetation - developed soil profile, only submerged once or twice each year

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