Unit 4 plate tectonics

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3.1.1 State the case study for a fault line
Sans Andreas fault
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When did it start to form?
15-20 million years ago (ref 2 )
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Where is it located?
California
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What type of plate boundary?
Conservative
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Which 2 plates are involved?
Pacific plate and the North American plate. Fig 1
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Which direction are the plates moving?
The same direction
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What does this do?
Causes the 2 plates to grind up against each other, resulting in compression and friction to 'build up'.
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The pressure continues to build up until...
it is overcome with a release of seismic energy in the form of an earthquake
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How long and deep is the fault and where is it located?
800 miles long and 10 m deep, located at the contact zone between the two plates
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How does the fault help to create a distinctive landscape?
long straight escarpments, narrow ridges, long banks and dips along the jagged rock and covers a great expanse of land (ref 2 )
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Furthermore....
"many stream channels characteristically jog sharply to the right when they cross the fault" (ref 2)
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3.1.2 state the case study for ground displacement
Haiti 2010
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What island is Haiti located on?
Hispaniola
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How do you spell Hispaniola?
H-i-s-p-a-n-i-o-l-a
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What type of plate boundary?
Conservative
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What 2 plates are involved?
North American plate and the Caribbean plate
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How many mm a year is the the Caribbean plate moving by?
7 (ref 2)
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The two plates slide past each other along the ....
Enriquillo-plantain Garden fault
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As with the Sans Andreas fault what builds?
pressure
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Who many years worth?
250 years (ref 6)
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Which was released in what?
an earthquake of magnitude 7 (ref 6)
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As a result of this seismic activity what took place?
Ground displacement
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It is though in a time scale of ....
less than 1 minute
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How did this displacement create a distinctive landscape?
number of buildings destroyed but also the fissures which showed the horizontal displacement in areas such as Port-au-Prince .
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How many cm was coastal uplift?
60cm
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In areas such as ..
Leogane
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Seismic progresses often cause landforms to be formed from a change in ...
topography or a deformation of land
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Which out of the 2 is more distinctive?
Sans Andreas fault
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Why?
1. The majority of the landscape formed after the earthquake will be changed as the country rebuilds 2. San Andreas started formation 15-20 million years ago so is a more permanent feature 3. San Andreas is also larger
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In the formation of batholiths no plate boundaries are involved, this is because...
it is an intrusive landform (figure 2)
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How was the Isle of Arran created?
by the intrusion of a large granite batholith that domed the sedimentary sandstone surface about 60 million years ago as Greenland separated from Scotland during the creation of the Atlantic Ocean (ref 1).
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Due to erosion and weathering processes the top of the....
granite batholith, which peaks at the height of 874m on Goat Fell (ref 1), is exposed.
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What is the height of Goat Fell?
874m
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State another feature of this landscape.
Series of dykes 2-3 m wide which look like natural rock groynes at the beach at Kildonan (ref 1)
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State the final feature of this landscape.
Exposed sill at Drumadoon (fig 2)which forms a cliff 50m high (ref 1)
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State the case study.
Mount Pinatubo
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Where is Mount Pinatubo located?
On the intersection between the Eurasian and Philippine plate
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At what kind of plate boundary?
Destructive
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Why are the sides of this volcano steeper?
Due to the type of lava that it emits at eruption
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As a consequence of the rock type, the type of lava produced is often...
andesitic or rhyolitic
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Both of these types of lava have...
a higher silica content than basaltic lava
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What does this cause the lava to be like?
more viscous - so when the volcano erupt the lava flows slowly and cools quickly
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Another distinctive feature of this type of volcano...
is the material making up their structure- alternative layers of ash and lava from previous eruptions (fig 3)
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How many eruptions has Mount Pinatubo had?
6 major explosions depositing significant amounts of material on the volcanoes sides
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Why are composite volcanoes distinctive landscape features?
provide a focal point, especially large and old volcanoes such as Mt Pinatubo which has been forming for the last million years
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Why is intrusive volcanic activity less significant than extrusive?
As without the contribution of other processes ie weathering ad erosion we would not be able to see bathoiths etc in the landscape
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Why else?
Extrusive volcanic larger and at a greater scale – more distinctive as more noticeable. Greater impact on the landscape.
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What are the 2 current hotpsots theories ?
Wilson (1963) and Foulger (2003)
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What is Wilson (1963), theory?
claimed that hotspots were stable plumes within the mantle, which the lithosphereic plate passed over
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What is Foulger (2003), theory?
postulated that hotspots were in fact weaknesses- a form of scaring , left over by marginal processes which cannot be seen today such processes resulted in “stretching and thinning” (ref 3), as the plate is pulled down at subduction zones.
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At hotspots a range of distinctive landforms can result, which help to ...
create an overall landscape which is distinctive.
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When intra-plate hotspots occur in oceanic plates, what can be formed?
submarine volcanoes
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What is a submarine volcano that never breaches the surface called?
seamount (figure 5),
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As a result it...
retains its peak like structure/shape
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Give an example of such a landscape feature
Loihi which is a seamount 30km off the coast of Hawaii
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If a seamount does breach sea level it is classified as, what?
a guyot (figure 5)
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As a consequence of what guyots have a distinctive shape?
erosion
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What does this demonstrate?
that to a large extent volcanic activity shapes the surrounding landscape
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Where can both forms of submarine volcanoes can be found?
in the Hawaii Island chain.
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At the Hawaiian island chain, shield volcanoes such as ...
Mauna Loa are formed (figure 6)
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What creates a gently sloping shape to the volcano?
The low viscosity of the basaltic lava
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Why?
as following extrusion from the Earth’s crust the lava will flow quickly covering a large surface area before cooling.
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The shape of the volcano helps create a distinctive landscape feature as ....
it has gentle sides and low land height- proving to be something that is easy to recognise
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What is a fissure eruption?
“a fracture or crack at the surface (of the volcano) from which lava erupts” (ref 2)
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Give an example
is Kilaue, Hawaii, which has had frequent fissure eruptions since 1983 (ref 2
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This is an example of volcanic activity can create a distinctive landscape feature, which ....
combined with the impressive shield volcanoes, can create a vast impact on the landscape.
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Shield volcanoes can also release proclastic flow, what is proclastic flow?
a “high density mix of hot lava block, pumice ash and volcanic gases “(ref 2).
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What can these effects flows have?
devastating effects on vegetation and natural landscape features, creating a unique and distinctive charred landscape.
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In summary hotspots can lead to the formation of a variety of landscape features such as
submarine volcanoes (Seamounts and Guyots). Island chains (Hawaiian) and shield volcanoes
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Each of these contribute to the overall distinctive landscape or
are in fact one in their own right (Hawaii).
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Why is it possible to say that to a large extent hotspots activity (volcanic extrusive) creates a distinctive landscape?
Because it creates a unique and responsible landscape that is known .
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To what extent does volcanic and seismic activity result in a variety of distinctive landscapes?
It can be said that to a large extent
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Through the examination of case studies, it can be concluded that ...
in the main extrusive volcanic activity produces a wider range of landscapes which are distinctive such as Mount Pinatubo.
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What causes this variety?
This variety is as a result of the differing plate boundaries, a result of convection currents and plate type (oceanic or continental)
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). Intrusive volcanic activity can be said to be less significant as ...
without other process such as erosion and weathering many of these feature such as Goat Fell (Isle of Arran) would not be exposed/seen or would not have the characteristic’ jagged edge’.
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Finally landforms created by seismic activity are distinctive, though
more established formations such as San Andreas Fault could be considered more so, as they have existed for a vast period of time and will continue to remain and grown.
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The same cannot be said for the ground displacement in Haiti as....
of the landscape that was created as a result of the seismic activity (earthquake) will have been cleared and rebuilding would have occurred. However changes in topography and uplift in coastal areas will remain, creating a distinctive landscape.
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Other cards in this set

Card 2

Front

When did it start to form?

Back

15-20 million years ago (ref 2 )

Card 3

Front

Where is it located?

Back

Preview of the front of card 3

Card 4

Front

What type of plate boundary?

Back

Preview of the front of card 4

Card 5

Front

Which 2 plates are involved?

Back

Preview of the front of card 5
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