2B.2 Geological structure influences the development of coastal landscapes at a variety of scales

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  • Created by: Lauraa.jt
  • Created on: 08-05-18 12:16
What three dimensions make up geological structure
strata, deformation and faulting
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What is strata
layers of rock and how they relate
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What is deformation
degree that rock units have been tilted or folded by tectonic activity
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What is faulting
fractures that have moved rocks from their origional position
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What are the two types of coasts that are produced by geological structure
concordant and discordant
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What are concordant coasts known as
Pacific coasts
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What are discordant coasts known as
Atlantic coasts
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What is a concordant coast
rock strata runs parallel to coast
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What is a discordant coast
different rock strata intersect the coast at an angle so geology varies
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What are discordant coasts dominated by and state the resistance of both features
1. Headlands - more resistant 2. Bays - less resistant
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Which is eroded more, a headland or bay? and how does this shape the coast
headland and this 'smooths' the coast by reducing the difference between headlands and bays
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Why does the smoothing of the coast occur
the effect that such coasts have on wave crests
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How do headlands and bays effect waves in deep water
wave crests are parallel
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How do headlands and bays effect waves in shallow water
slow down and height increases
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How do headlands and bays effect waves in bays
wave crests curve to fill the bay and wave height decreases
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How do headlands and bays effect straight wave crests
they refract, become curved and spread out in bays and concentrate on headlands
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What is the overall effect of wave refraction
concentrate powerful waves at headlands (greater erosion) and create lower, diverging wave crests in bays (less erosion)
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Name an example of a concordant coast in the UK and abroad
around Lulworth Cove, Dorset and the coast of Dalmatia, Croatia in the Adriatic Sea
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The coast of Dalmatia was drowned during the.....
holocene
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What is the holocene
the geographical epoch that began 12,000 years ago causing sea levels to rise
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What is the geology of Dalmatia
limestone
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How has Dalmatia been effected by tectonic activity
folded into a series of anticlines and synclines parallel to the coast , the upstanding anticlines and lower syncline basins drowned by rising sea levels to create a concordant coast of long, narrow islands arranged offshore
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Give an example of another type of concordant coast
Haff coast
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Where are haff coasts found
southern fringes of the Baltic Sea
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What are haff coasts
long sediment ridges topped by sand dunes run parallel to the coast just offshore, creating lagoons (haffs) between the ridges and the shore
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What are the two dominant characterisitcs of cliff profiles
1. the resistance erosion of the rock 2. the dip of rock strata in relation to coast
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What does dip mean
the angle of the rock strata in relation to the horizontal and is a tectonic feature as when sedimentary rocks formed in horizontal layers can be tilted by plate tectonic movement
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Explain horizontal dip
vertical or near vertical profile with notches reflecting strata that are more easily eroded
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Explain seaward dip, high angle
sloping, low angle profile with one rock layer facing the sea; vulnerable to rock slides down the dip slope
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Explain seaward dip, low angle
profile may exceed 90 degree producing areas of overhanging rock; very vulnerable to rock falls
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Explain landward dip
steep profiles of 70-80 degree producing a very stable cliff with reduced rock falls
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Alongside dip of strata, what other 3 features influence cliff profiles and rates of erosion
Faults, joints and fissures
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What are faults
major weaknesses within rock layers, either side of a fault line, rocks are heavily broken and fractures and weaknesses are exploited by marine erosion
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What are joints
regular patters, dividing up rock strata into blocks with a regular shape
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What are fissures
smaller cracks in rocks, few cm or mm long, easily exploited
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What are micro features in rocks and what are they controlled by
caves and wave cut notches controlled by location of faults/strata and have high density of joints and fissures
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Why does folding occur
crustal compression
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When horizontal strata are 'squeezed' what happens
folded into a series of anticlines and synclines
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What are the two types of folds
anticlines (convex up A shapes) and synclines (concave down U shaped)
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Do the two types of fold occur together or separate
together
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Other cards in this set

Card 2

Front

What is strata

Back

layers of rock and how they relate

Card 3

Front

What is deformation

Back

Preview of the front of card 3

Card 4

Front

What is faulting

Back

Preview of the front of card 4

Card 5

Front

What are the two types of coasts that are produced by geological structure

Back

Preview of the front of card 5
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