2B.1 The coast, and wider littoral zone has distinctive features and landscapes

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  • Created by: Lauraa.jt
  • Created on: 07-05-18 21:33
What 3 things make coasts a dynamic environment
1. boundary zone - land and sea meet + marine and terrestrial processes operate and interact 2. experience extreme events which are rare but cause change e.g. tropical storms, cyclones, tsunami's 3. human development constant change
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What are the 4 sub zones of the littoral zone
Backshore, Foreshore, Nearshore, Offshore
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What happens in the backshore
above high tide level and is only affected by waves during spring tides
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What is a spring tide
an exceptionally high high tide
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What happens in the foreshore
wave processes are confined here between high and low tide marks
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What happens in the nearshore
shallow waters, one of intense human activity e.g. fishing and leisure, also part of the physical system - transfers of sediment by currents close to shore
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What happens in the offshore
waves form
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What are the two main types of coast
1. Rocky (cliffed) 2. Coastal plains (alluvial coasts)
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What are rocky coasts
cliffs vary in height from a few m to 100's of m , formed from rock but hardness varies
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What are coastal plains
land gradually slopes towards the sea across an area of deposited sediment e.g sand dunes and mudflats
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What are the 3 types of contrasting coastlines
cliffed, sandy and estuarine
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What is a cliffed coast like
transition from land to sea is abrupt, low tide the foreshore zone is exposed as a wave cut platform
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Give an example of a cliffed coast
chalk cliffs at Flamborough
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What is a sandy coast like
high tide it is inundated but dunes are not, dune vegetation stabilises the coast and prevents erosion
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Give an example of a sandy coastline
sand dunes in Belgium
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What is an estuarine coast like
extensive mudflows, cut by channels are exposed at low tide but inundated at high tide, closer to the backshore the mud flats are vegetated forming a salt marsh, gradual transition from land to sea
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Give an example of an estuarine coastline
mouths of rivers e.g. Lymington in Hampshire
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How can coasts be classified
1. Formation processes 2. Relative sea level change 3. Tidal range 4. Wave energy
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Classifying coasts - formation processes
1. Primary coasts - dominated by land based processes e.g. deposition from rivers/new coastal land forms from lava flows 2. Secondary coasts - marine erosion or deposition processes
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Classifying coasts - relative sea level change
1. Emergent - rising e.g. tectonic uplift 2. Submergent - flooded by the sea due to rising sea level/subsiding land
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Classifying coasts - tidal range
1. Microtidal 0-2M 2. Mesotidal 2-4M 3. Macrotidal 4M+
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Classifying coasts - wave energy
1. Low energy - sheltered, limited fetch, low wind speeds = small waves 2. High energy - exposed, prevailing winds + long wave fetch = powerful waves
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How much of the UK has rocky cliffs and discuss in terms of relief
1000km and relief is variable
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Give three examples of very high cliffs
1. Hangman's cliffs in Devon = 318m above Bristol Channel 2. Boulby cliff, North Yorkshire = 203 m above North Sea 3. Conachoir on Hirta in the Outer Hebrides = 427m , highest in the UK
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What are the two main types of cliff profiles
1. Marine erosion dominated 2. Sub-aerial process dominated
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What are the characteristics of a marine process dominated cliff profile
Steep face, vegetated, limited cliff base debris as it is quickly broken up by erosion and washed away
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What are the characteristics of a subaerial process dominated cliff profile
curved slope, lower relief and not actively eroded at base, surface run-off and mass movement move sediment downslope but little is carried away by marine erosion
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What type of rock do subaerial processes affect the most
less resistant rock e.g. shale, clay and mudstone
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What are the three subaerial processes
weathering, mass movement, surface run off
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What is weathering
te breakdown of rocks into smaller fragments and new minerals in situ
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What is mass movement
movement of material downslope under the influence of gravity
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What is surface runoff
water flowing down cliff face = erosion
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What three things influence how resistant rock is to erosion
1. How reactive the minerals in rock are to chemical weathering 2. Whether rocks are clastic or crystalline 3. degree to which rocks have cracks, fractures and fissures
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Erosion resistance - number 1
calcite in limestones weathered by solution whereas quartz in sandstone is no subject to chemical weathering
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Erosion resistance - number 2
CLASTIC = sedimentary rocks e.g. sandstones made of cemented sediment particles so are erosive CRYSTALLINE = igneous and metamorphic rocks made of interlocking crystals and are more resistant to erosion
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Erosion resistance - number 3
easily exploited by forces of weathering and erosion
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Name the three minerals that make rocks weak
iron oxide, calcite and quartz
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What is the most weak type of rock
unconsolidated e.g. bouder clay
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What is the coastal recession rate (cm per year) for granite (igneous)
0.1 to 0.3 cm per year
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What is the coastal recession rate (cm per year) for limestone (sedimentary)
1 to 2 cm per year
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What is the coastal recession rate (cm per year) for chalk (sedimentary)
1 to 100 cm per year
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What is the coastal recession rate (cm per year) for sandstone (sedimentary)
10 to 100 cm per year
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What is the coastal recession rate (cm per year) for boulder clay (unconsolidated)
100-1000 cm per year
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What is a coastal plain
an area that is low lying, low relief, contain wetlands and marshes because they are just above sea levels and are poorly drained due to flatness of landscape
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What two ways to coastal plains form and give examples
1. fall in sea level = seabed what was once a shallow continental shelf is exposed e.g. Atlantic coastal plain USA 2. Deposition of sediment from land brought to coast by rivers can cause coastal accretion where coast moves seaward e.g delta
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Many coastal plains are in a state of...and why
dynamic equilibrium due to balancing forces 1. Deposition from river systems inland + deposition of sediment from offshore and longshore sources 2. Erosion by marine action
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Other cards in this set

Card 2

Front

What are the 4 sub zones of the littoral zone

Back

Backshore, Foreshore, Nearshore, Offshore

Card 3

Front

What happens in the backshore

Back

Preview of the front of card 3

Card 4

Front

What is a spring tide

Back

Preview of the front of card 4

Card 5

Front

What happens in the foreshore

Back

Preview of the front of card 5
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