Geography Restless Earth (Physical)

What is the crust?
The outer layer of the Earth
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What is a plate?
A section of the Earth's crust
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What is a plate margin?
The boundary where 2 plates meet
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What is the mantle?
The dense, mostly solid layer between the outer core and the crust
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What are convection currents?
The circular currents of heat in the mantle
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What is the core?
The centre of the Earth. It is split into the solid inner and molten outer core
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What are the 2 different types of crust?
Oceanic crust and Continental Crust
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Compare the difference between the Oceanic crust and Continental crust
The oceanic crust is newer (most less that 200 million year old) where as the continental is mainly over 1500 million years old. Oceanic crust is denser and can sink comparedto the continental crust is less dense and connot sink.
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Describe contructive plate margins
Plates move apart. This type of movement mostly happens under the oceans. Crack and fractures form between the plates and magma rises up. It forms lava flows and very shallow shield volcanoes.
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Draw a diagram of a Constructive Plate Boundary
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Describe a destructive plate margin
Plates move together. If one plate is oceanic crust and the other continental crust then the denser oceanic crust sinks under the lighter continental crust (Subduction zone).
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What is the subduction zone
An oceanic trench
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Where are composite cone volcanoes formed?
At destructive plate margins. The oceanic poate sinks there is great pressure and the oceanic crust is destroying and it melts forming magma. The magma rises upwards causing volcanic eruptions and leading to the formation of them
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Describe collision plate margins
When 2 continental plates collide. The plates are pushed up forming fold mountains. Destructive earthquakes can also occur on faults in colliion zones.
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Draw a diagram of a destructive plate margin
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Draw a driagram of a collision plate margin
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Describe a conservative plate margin
When the plates slide past or next to each other. They are moving in a similar (not the same) direction. One plate is moving faster than the other and in a slightly different direction and they tend to get stuck. Causing friction and pressure builds.
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Draw Diagram of a conservative plate margin
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What are fold mountains?
Are large mountain ranges where rock layers have been crumpled as they have been forced together. For example the Alps
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Draw a Diagram of how Fold moutains are formed
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What are the features of fold mountains?
Anticline: Upfold of folded rock. Syncline: Downfold of folded rock. Overfold: Where a fold has been pushed over on one side
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What is an ocean trench?
Are deep sections of the ocean, usually where an oceanic plate is sinking below a continental plate. Form some of the deepest parts of the ocean.
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Draw a diagram of how the ocean trenches are formed
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Why is relief a physical problem in fold mountains?
Mainly high and steep. There are rock outcrops and narrow valleys. This means there is little flat land for farming or building settlements
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Why is climate a problem in fold mountains?
With increasing hight the climate becomes colder, windier and wetter (with more snow). The growing season is short - it's often impossible to grow crops at high levels
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Why are soils a problem in fold mountains?
Mountain soils are typically stony, think and infertile
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Why is accessibility a problem in fold mountains?
Roads and railways are expensive and difficult to build. Travel is disrupted by rock falls, avalanches and bad weather.
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What is a volcano?
Is a cone-shaped mountain formed by surface eruptions from a magma chamber inside the earth
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What is magma called when it's reaches the surface?
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Draw a shield volcano and label the characteristics
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Draw a composite cone volcano and label the characteristics
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What are the differences between the 2 types of volcano?
A sheild volcano is formed at a constructive plate margin and forms when magma rises to fill the gap between the plates. A composite cone volcano forms at a destructive plate margin and magma in the subduction zone is under pressure and may be forced
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State 2 differences between acid and basic lava
Acid lava has a high silica content meaning it's more viscous (than basic lava which form a shield volcanoes) so it travels a shorter distance before cooling
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How are supervolcanoes different?
Eruption is 1000 times bigger. So must dust is ejected into the atmosphere that global cooling occurs.
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What are the primary and secondary effects of a volcano?
Primary: People injured or killed. Buildings and farmland destroyed. Communications disrupted. Secondary: Costs of rebuilding. Tourists might stay away. Ash improves soil fertility.
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What are the positive and negative impacts?
Positive: Fertile soil. Tourist attractions. Natural hot springs Negative: Always destructive. Global dimming. Unpredictable so it's difficult to prepare
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What are the 2 ways in which you can monitor volcanoes?
1- Tiltmeters which check the bulges on volcano slopes 2- satellites which monitor for changes in heat activity
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What is an earthquake?
Is the shaking of the earths crust due to the movement of tectonic plates. These occur at any plate boundary
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Why do earthquakes occur at destructive plate boundaries?
The pressure from the sinking of the subducting plate and its subsequent melting can trigger strong earthquakes as this pressure is periodically releases
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Why do earthquakes occur at conservative plate margins?
The plates slide past each other, the plates tend to stick for periods of time. This causes pressure to build and when released it jerks the plates
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Why do earthquakes occur at constructive plate margins?
The friction and pressure caused by the plates moving apart can trigger earthquakes
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What is the focus point
The point in the earth's crust where the earthquake originates. The shaking is worse on the surface if the focus is shallow.
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What is the epicentre?
The point at the earth's surface directly above the focus
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What are shock waves?
Seismic waves generated by an earthquake that pass through the earth's crust
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What are the 2 ways of measuring an earthquake?
1- The richter scale is used by seismographs to measure an earthquake's magnitude with values plotted n a logarithmic scale 1 to 10 2- The Mercalli Scale measures the impact on people based on human judgement - roman numerals
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What are the primary and secondary effects of an earthquake?
Primary: Collapsing buildings, roads and bridges. People killed/injured Secondary: Fires. Tsunamis. Landslides. Disease
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What are physical factors controlling the effects of an earthquake?
High level of damage: High magnitude on richter scale, shallow focus, sands and clays vibrate more. Low level of damage: Low magnitude (below 5). Deep focus. Hard rock surface
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What are the human factors controlling the effects of an earthquake?
High level of damage: High density of population. Residential area of city. Self-built housing. Low Level of damage: Low desity population. Urban area with open spaces. Earthquake proof buildings
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What are the 3 Ps
Prediction, Protection, Preparation
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How to make a building that will not collapse
-computer controlled weights on the roof to reduce movement -Steel frames(sway) -Fire resistant building materials -Foundations sunk into bedrock (avoiding clay)
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What is a tsunami?
Is a special type of wave where the entire depth of the sea or ocean is set in motion by an earthquake which displaces the water above it and creates a huge wave
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How does a tsunami form?
Caused by earthquakes at sea. Energy from an earthquake vertically jolts the seabed by several metres displacing hundreds of cubic meters of water. Large waves begin to move through the oceans away from the epicentre.
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What happens to a tsunami as is reaches shallow water?
The tsunami slows but increases in height
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Other cards in this set

Card 2


What is a plate?


A section of the Earth's crust

Card 3


What is a plate margin?


Preview of the front of card 3

Card 4


What is the mantle?


Preview of the front of card 4

Card 5


What are convection currents?


Preview of the front of card 5
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