C2a: The Structure of the Earth

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Describe the structure of the Earth
A sphere with a thin rocky crust, a mantle and an iron core
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How does the movement of tectonic plates result in volcanic activity and earthquakes?
Earthquakes&volcanic eruptions happen at the boundaries between plates,& the crust may ‘crumple’ to form mountain ranges. Magma (molten rock) is less dense than the crust. It can rise to the surface through weaknesses in the crust, forming a volcano.
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What happens where tectonic plates meet?
the Earth's crust becomes unstable as the plates push against each other, or ride under or over each other.
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What is the movement of tectonic plates?
Very slow (about 2.5cm per year)
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What were timescales involved in?
The movement of continents
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What do Earth scientist's accept?
The theory of plate tectonics
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How many theories have been put forward to explain the nature of the Earth's surface?
Many
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What is the size of the crystals in a igneous rock related to?
The rate of cooling of molten rock because Igneous rocks are made when molten rock cools down and solidifies. The slower the molten rock cools, the larger the crystals become.
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What is magma?
Molten rock beneath the surface of the Earth
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What is lava?
Molten rock at the Earth's surface
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Name two types of lava that volcanoes may erupt.
1. runny lava 2. thick lava - violently and catastrophically
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Why do some people chose to live near volcanoes?
Because volcanic soil is very fertile. It contains minerals needed by plants for healthy growth.
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What is the lithosphere?
The relatively cold rigid outer part of the Earth that includes the crust and part of the mantle
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What is the lithosphere made of?
Tectonic plates that are less dense than the mantle below.
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What are the two problems associated with studying the structure of the Earth?
The crust is too thick to drill through and the need to use seismic waves produced by earthquakes or man-made explosions.
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Why is the theory of plate tectonics now widely accepted?
Because it explains a wide range of evidence, and it has been tested and discussed by a wide range of scientists.
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Describe the mantle.
It is the zone between the crust and the core which is cold and rigid just below the crust, and hot and non-rigid at greater depths and therefore able to move
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Card 2

Front

How does the movement of tectonic plates result in volcanic activity and earthquakes?

Back

Earthquakes&volcanic eruptions happen at the boundaries between plates,& the crust may ‘crumple’ to form mountain ranges. Magma (molten rock) is less dense than the crust. It can rise to the surface through weaknesses in the crust, forming a volcano.

Card 3

Front

What happens where tectonic plates meet?

Back

Preview of the front of card 3

Card 4

Front

What is the movement of tectonic plates?

Back

Preview of the front of card 4

Card 5

Front

What were timescales involved in?

Back

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