eqi1 Flashcards
(81 cards)
1
Q
what is the littoral zone?
A
the boundary between land a sea - dynamic zone
2
Q
what are the 4 zones of the littoral zone?
A
1 - backshore - above high tide
2 - foreshore - between high and low tide
3 - near/inshore - between low tide and deep water
4 - offshore - deep water beyond the influence of the waves
3
Q
what affects the backshore?
A
- marine processes from tropical storms - rain brings sediment to the beach
- rain and wind as opposed to marine processes - weathering processes
- human interference
4
Q
what is the foreshore affected by?
A
daily change from high and low tides nd sediment dropping
5
Q
what are the short-term things changing the littoral zone?
A
NATURAL:
- tides
- weather
HUMAN:
- management - beach replenishment
- tourism - trampling sand dunes
- dredging
6
Q
what are the long-term things changing the littoral zone?
A
NATURAL:
- weathering
- seasons
- climate change
HUMAN:
- management - soft/hard engineering
- climate change
7
Q
what are the inputs of the coast?
A
- sediment from sea and currents
- weathering and mass movement occuring on the backshore
- marine inputs (waves and tides)
- terrestrial (e.g. tectonic activity)
- biogenic (shells and marine fossils)
- atmospheric (climate change, wind and rain)
- human activities (dredging, defenses)
8
Q
what are the coastal processes?
A
- deposition
- changes in sea level
- long shore drift
- erosion
9
Q
what are coastal outputs?
A
- different classifications of coasts
- erosional landforms (stacks, stumps)
- depositional landforms (beaches, spits, sand dunes)
10
Q
what are different coastal characteristics?
A
- sediments (shingle, sand, mud)
- relief (height and steepness of coast)
- geology (structure of earth)
- lithology (strength, jointing, bedding)
11
Q
what are sediment cells?
A
a section of coastline that is involved in the complete cycle of sediment transport and deposition
- they are discrete and function seperately
- they are bounded by significant physical disruptions to the coastline
- sediment is sourced, transferred and stored within each cell
12
Q
how many sediment cells in england and wales?
A
11
13
Q
how can coasts be classified?
A
Valentin’s classification of coasts divides coasts into 2 groups:
advancing and receding coasts
14
Q
what are the advancing coasts?
A
- emergence coasts e.g. NW scotland (from sea level fall)
- deposition coasts e.g. SE england (building up of sediment)
14
Q
what are the retreating coasts?
A
- eroding coast (North norfolk)
- submerging coast (cornwall) sea level rise
15
Q
what do we classify coasts on?
A
SHORT-TERM INFLUENCES
- high/low energy (waves)
- primary and secondary coasts (sediment)
- balance between erosion and deposition
- tidal range
LONG-TERM INFLUENCES
- geology
- changes in sea level
16
Q
what is the fetch?
A
the distance over ocean or sea over which wind has blown
17
Q
what is a high fetch?
A
high fetch = high wind = high energy
SW atlantic
18
Q
what is low fetch?
A
low fetch = low wind = low energy
SE england
19
Q
what are the characteristics of high energy coasts?
A
- destructive winds
- storm conditions
- long fetch
- erosion and transportation
- cliffs
- rocky
- wave cut platforms
20
Q
what are the characteristics of low energy coasts?
A
- constructive coasts
- deposition and transport
- lowland coasts
- beaches and spits
21
Q
what are the different coastal ranges?
A
microtidal coasts - 0-2 m
mesotidal coasts - 2-4m
macrotidal coasts - 4m+
22
Q
what is geology?
A
study of its origins and nature of the earth’s crust and rocks which it’s composed
23
Q
what is lithology?
A
description of the physical characteristics and formation of rock
- strata
- angle of dip
- joints
- folds
- faults
- bedding planes
24
what is geomorphology?
study of landforms - evolution and processes involved in formation of earth
25
what are igneous rocks?
formed from the solidification of molten material mostly crystaline and very resistant to erosion
- magma cooling above ground = basalt
- magma cooling below ground = granite
in the cooling process joints are formed that are more susceptible to weathering
26
what are sedimentary rocks?
formed in the accumulation and cementation of sediments at earth's surface and in water
- bedding planes separate each layer
- less resitant to marine erosion
27
what are metamorphic rocks?
sedimentary and igneous rocks that are modified by heat, pressure and chemical processes
- most resistant to coastal erosion as they don't have bedding planes
28
what are tides?
created by the gravatational pull of the sun and moon
4 tides every 24 hours (or so)
29
30
what are spring tides?
spring tides are when the sun, moon and earth are in line with one another (in any order)
- they result in tides that are much higher (high) than usual or lower (low) then usual
they have the greatest tidal range
31
what is the impact of tidal ranges?
low tidal range = narrow beach prone to higher erosion
high tidal range = wide zone of attack resulting in formation of wide wave cut platforms in many places
32
what are neap tides?
the sun and moon are at a 90 degree angle to the earth
- they have a small tidal range
33
what is the north sea storm surge case study?
- killed 2,500 people
- damage ~£1.2 bn
- wides of over 140m/hr and gale force winds drove the storm waves and a storm surge of 5.8m
- 18,000 people evacuated
- 800,000 homes protected due to flood management
34
what is the tacloban 2013 storm surge case study?
- winds up to 315 km/hr
- 6200 killed
- 28,000 people injured
- storm surge reached up to 7m
- 14.1million affected
- 4.1 million displaced
35
what are bedding planes?
layers of sediment that represent surfaces of exposure that occured between depositional events
36
how does cliff structure create distinctive features?
toppling failure - joings opened by weathering release slas dipping forward
bedding plane slip - rock slabs slide down the cliff along bedding planes to form a steep cliff
37
what is competent rock?
strata is >30cm thick and rock is strong
38
what is incompetent rock?
strata is <30cm thick and rock is weak
- rocks readily slip over another especially when wet
39
what impact does low angle of dip, lots of master joints and being steep have on cliffs?
- vulnerable to toppling failure
39
what impact does horizontal bedding planes and marine erosion on cliffs?
- stable cliff and steep
- wave cut platform
40
what impact does seaward dip, collapse on bedding planes have on cliffs?
low cliff profile
steep seaward dipping cliffs
angle of cliff will resemble that of the tilt
40
what impact does landward dip of strata have on cliffs?
steep and stable cliffs are produced with reduced rock fall
41
what impact does landward dip of strata but very jointed have on cliffs?
mass movement along joints that acts as sliding planes
42
what are discordant coastlines?
where the bands of different rock run at right angles to the coast
- differential erosion
43
what are the characteristics of discordant coastlines?
- headlands
- bays
- caves
- arches
- stacks
- stumps
44
what are concordant coastlines?
where bands of rock run parallel to the coastline
- distinctive landforms e.g. cove `
45
what are dalmatian coastlines?
a concordant coast - the folding of limestone landscape into synclines and anticlines
- sea level then rises, flooding the synclines resulting in elongated island running parallel to the coast
46
what are haff coastlines?
concordant coast - a spit runs parallel to a coastline and has a lagoon behind it
46
how does geology affect the coastal landforms on dorset coast?
- many headlands e.g. pevril point along east coast
- cliffs due to coastal erosion and arches, stacks and stumps e.g. old harry
- along the south coast is a concordant coastline with no features
47
how does lithology created distinctive coastal features on dorset coast?
geological formations are composed of limestone and clay and chalk
- durdle door shows the rates of differential erosion - the front is wider and is limestone and behind is clay and sandstone
47
how does limestone resist erosion?
limestone resists erosion better than the surrounding rocks in lulworth cove because it is a harder sedimentary rock
48
how does clay resist erosion?
clay is a much softer rock and is eroded easier
- it is prone to slumping which can be seen by the aggressive erosion behaing the limestone which created an area of low energy
49
what are sand dunes?
plant succession on sand is called a psammosere
50
what is plant succession?
series of plants that develop as the enrivonment changes
51
what are xerophytes?
plants that can tolerate very dry conditions
e.g. sand dunes
52
what are salt marshes?
plant succession in saline conditions is called a halosere
53
what are halophytes?
plants that can tolerate very salty conditions
54
what are the characteristics of embryo dunes?
- PH = 8
- dynamic
- yellow colour
- 1% humus
- 0-50 yrs old
prickly saltwort pioneers
55
how do embryo dunes form?
1) obstacles such as driftwood can trap sediment being blown up the beach through the process of saltation
2) pioneer plants will colonise in build up of sediment
56
what is the environment for embryo dunes?
- high water mark
- on shore winds
- seaweed deposits humus
- transient dunes
- sand alkaline
- poor water retention
57
what are the plant adaptations for embryo dunes?
- waxy leaves to retain moisture and withstand winds (sandwort)
- low habit to avoid winds (saltwort)
- deep roots to obtain little moisture
- high salt tolerance ( sea rocket)
58
what are the characteristics of a yellow dune?
- PH=7.5
- dynamic
- 2.5% humus
- yellow colour
- 50-100 yrs
- marram grass
59
what is the formation of yellow dunes?
1) unique rhizome root system of marram grass able to withstand the lack of water and salty conditions, stabalises the sediment and allows more sand to be trapped
2) height of dune increases as more sand is trapped
60
what environment do yellow dune need?
- soil is slightly less alkaline
- above the level of high tides
- some humus forming
- reduced wind speeds
61
what plants are in yellow plants?
the dominant plants are marram grass
- salt tolerance
- thrives buried in sand
- long tap roots
- underground rhizomes stabalise the ground
62
what are the characteristics of grey dunes?
- 250+ yrs
- PH =6
- fixed
- brown colour
- woodland
- 40% humus
63
how do grey dunes form?
1) shelter conditions behind yellow dunes are more favourable for a greater range of species
2) greater vegetation cover results in more decomposing matter that increase the humis and increases the acidity = more plants can survive this way
3) greater water retention
4) root systems fix the dunes in place
63
what environment is needed for grey dunes?
- lower PH
- sand not accumulating
- little mobile sand
- closed vegetation community
64
what plants are in the grey dunes?
- higher species diversity
- mainly perennials
- marram becomes sparse
- surface lichens give grey appearance
65
what environment is needed for dune slacks?
- acidic soil
- relief intersects the water table
- high water table
65
what plants are in the dune slacks?
moisture loving plants commonly found in many fresh water wetlands:
- rushes
- phragmites reeds
- bog cotton
66
what environment is needed for dune heath?
- well sheltered from winds
- maritime influence is minimal
- acidic soil
- organic matter in soil
67
what are the plants in the dune heath?
human interference means that true mixed woodland climax veg is rarely seen most dune systems develop into:
- heathland
- woody perennials
- scattered trees
68
why does flocculation occur?
as fresh water mixes with salt water for example where a river meets the sea, and is the process by which tiny particles in suspension like clay or silt coagulate with the salt in the water by chemical reaction and become heavy and are deposited
68
what is a salt marsh?
plant succession in saline conditions is called a halosere
69
how does flocculation play a key role in the formation and stabalisation of mud flats and salt marshes?
- particle aggregation = as the clumps become heavier, they settle more readily
- mudflat formation = the aggregated sediments help build up and stabilise mudflats
- floccualtion influences the transport and distribution of sediments
70
what are the pioneer plants found at low tides?
- salicornia
- spartina
71
what factors affect salt marsh development?
- weather: storms can erode the marsh
- river regime: changefs in currents and volume can affect erosion
- sediment supply: supply changes can enhance or diminish the available silt
- human action: commercial, industrial and recreational activity can damage marsh
- sea level: rises can upset equilibrium and destroy the marshes
- climate: affects species types, growth rates and sea levels
- wave type: changes in direction, nature and size can affect marsh stability
72
what are direct human threats to salt marshes?
- industrial pollution: may harm many marsh species - oil pollution = decline of spartina
- agricultural pollution: led to eutrophication and the disruption of marine and marsh ecosystems
- dredging: removes sediment which may reduce mudflat accumulation
- commercial and recreational shipping and water sports activities can erode marshes
- grazing: can cause trampling of species and alterations to species diversity by selective eating
73
what are natural threats to salt marshes?
- sea levels may rise too quickly for the marshes to adjust. increased of storms leads to increased flooding
- storms create greater wave energy and more potential erosion and may lead to a loss of sediment supply
- changing temperatures and rainfall patterns may affect the tolerance of marsh species
