Physical Geography

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Properties of continental crust
thick and less dense
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Properties of oceanic crust
thinner and more dense
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What is a destructive margin?
plates moving towards each other, oceanic and continental plate meet, oceanic is forced down and destroyed - creates volcanoes and oceanic trenches. Or where the plates meet and smash together, but none is destroyed.
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What is a constructive margin?
two plates moving away from each other, magma rises, cools and creates new crust (sea floor spreading)
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What is a conservative margin?
plates moving past each other at different speeds
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How are fold mountains created?
when plates collide at destructive plate margins, sedimentary rock forced upwards. Or when continental plates collide.
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Describe how a volcano is formed
at desructive margins. oceanic plate moves down into mantle, destroyed, pool of magma forms, magma rises through vents in the crust, erupts onto surface
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Describe a composite volcano
made from ash and lava that's erupted, lava thick and flows slowly, hardens quickly - steep sided.
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Describe a shield volcano
made up of lava, lava runny, flows quickly, low, flat shape.
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Describe a dome volcano
made up of lava, lava thick, flows slowly, steep sided
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describe how a supervolcano is formed
magma rises up through cracks to form a large magma basin below the surface, bulge cracks, creating vents for lava to escape through - erupts causing earthquakes and ash, collapses, after eruption, caldera is left.
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describe the characteristics of a supervolcano
flat, cover a large area, have a caldera
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describe how a earthquake occurs at a destructive margin
tension builds up when one plate gets stuck as it's moving down past the other into the mantle
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describe how a earthquake occurs at a constructive margin
tension builds along cracks within the plates as they move away from each other
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describe how a earthquake occurs at a conservative margin
tension builds up when the plates get stuck gliding past each other
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describe the Richter Scale
measures the amount of energy released from an earthquake (magnitude which is measured by a seismometer).
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what does 'logarithmic' mean in terms of the Richter Scale
if an earthquake has a magnitude of 5 it means it's 10 times more powerful than a earthquake with a magnitude of 4. (1-9+)
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describe the Mercalli scale
measures the effects of an earthquake (1-12)
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what does the long profile of a river show you?
how the gradient changes over different courses
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what does the cross profile show you?
what a cross-section of the river looks like
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describe the upper course of the river
steep, v-shaped valley, steep sides, narrow, shallow channel
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describe the middle course of a river
medium gradient, gently sloping valley sides, wider, deeper channel
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describe the lower course of a river
gentle gradient, very wide, almost flat valley, very wide, deep channel
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what is vertical erosion?
the water deepens the river valley making it v-shaped - dominant on the upper course of the river
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what is lateral erosion?
widens river valley - dominant in middle and lower courses
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name the four processes of erosion
hydraulic action, abrasion, attrition, solution
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name the four processes of transportation
traction, saltation, suspension, solution
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describe a few reasons why rivers slow down and deposit material
the volume of water falls, the amount of eroded material increases, water is shallower, the river reaches it's mouth
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describe meanders
current is faster on the outside of the bend, because channel is deeper, so more erosion happens on the outside of the bend, forming river cliffs. current slower in inside bend because channel is shallower, material deposited forming slip-off slopes.
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describe how ox-bow lakes are formed
in a meander, erosion causes outside bends to get closer, until there's a small bit of land left between bends which is called a 'neck', river breaks through and river flows through shortest course, deposition eventually cuts off meander forming lake
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describe the creation of a waterfall and gorge
river flows over area of hard rock followed by soft rock, which gets eroded, creating a 'step', steep drop formed, hard rock undercut by erosion, collapses. loose rocks swirl around at foot of waterfall and erode, waterfall retreats leaving gorge.
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what is a flood plain?
the wide valley floor on either side of a river which gets flooded, this slows downs river and material is deposited making flood plain higher
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what is a levee?
natural embankments along the edges of a river channel, during a flood, material deposited on flood plain, build up of deposited material
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what are the four main physical factors for river flooding?
prolonged rainfall, heavy rainfall, snowmelt, relief
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give two human factors which cause river flooding
deforestation, building construction (impermeable materials)
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describe dams and reservoirs and the +'s -'s of using them to prevent flooding
dams are built across rivers, reservoir is formed behind. +'s - stores rainwater, drinking water, HEP. -'s - expensive, flood settlements
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describe flood warnings and the +'s -'s of using them to prevent flooding
warnings are given through the media to the public, +'s impact of flooding reduced, evacuation -'s - doesn't stop the flood from happening, hard to get insurance, people may not find out
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describe the difference between hard engineering and soft engineering
hard - man-made to control flow of rivers soft - schemes using knowledge to reduce effects of flooding
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explain how the UK could manage demand for water
transfer water from areas of surplus
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what issues could water transfer cause?
expensive, affect wildlife, political issues
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explain how people could reduce the amount of water usage
taking showers instead of baths, water meters
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Other cards in this set

Card 2

Front

Properties of oceanic crust

Back

thinner and more dense

Card 3

Front

What is a destructive margin?

Back

Preview of the front of card 3

Card 4

Front

What is a constructive margin?

Back

Preview of the front of card 4

Card 5

Front

What is a conservative margin?

Back

Preview of the front of card 5
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