AQA Geography: Restless Earth Revision Notes

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  • Created on: 06-11-12 22:27
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Geography [TOPIC 2 ­ RESTLESS EARTH (PLATE TECTONICS)]
The outer layer of the earth. Ranges in thickness
Crust
between 6 to 70km.
Filled with magma. Temperatures range from
Mantle
5000°C to 13000°C.
Outer Core Is liquid and largely made up of iron.
Solid and also made up of iron. Temperatures
Inner Core
within the dense core can reach 5,500°C.
Plate A section of the Earth's crust
Plate Margin The boundary where two plates meet.
Convection Current The circular currents of the heat in the mantle.
A mountain with a crater or vent through which lava
Volcano
erupts
Magma Molten rock below or within the earth's crust
Lava Molten rock erupting from a volcano
A collection of magma inside the Earth, below the
Magma Chamber
volcano.
Volcanic Bombs Lumps of molten rock that solidify as they fall
Pyroclastic Flow Hot gases and steam which flows from a volcano
Mudflows caused by the combination of volcanic
Lahars
materials and water.
A volcano capable of producing a volcanic eruption
Super Volcano
greater than 1,000 cubic kilometres
Vibrations caused by the earth's movements at
Earthquake
plate boundaries and at major fault lines
Point at which the rock moves (origin of the
Focus
earthquake)
Seismic Waves Shockwaves which start at the focus
Epicentre Directly above the focus on the earth's surface
Tsunami Tidal waves triggered by underwater earthquakes.
Fold mountains at destructive or collision plate
Fold Mountains
boundaries
Ocean Trenches Lowest place on the surface of the earth

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Geography [TOPIC 2 ­ RESTLESS EARTH (PLATE TECTONICS)]
The Earth is over 4600 million years old
There are two types of crust; oceanic crust and continental crust
Oceanic Crust Continental Crust
Newer ­ less than 200 million years old Older, over 1500 years old
Denser Less dense
Can sink Cannot sink
Can be renewed and destroyed Cannot be renewed or destroyed…read more

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Geography [TOPIC 2 ­ RESTLESS EARTH (PLATE TECTONICS)]…read more

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Geography [TOPIC 2 ­ RESTLESS EARTH (PLATE TECTONICS)]
PLATE BOUNDARIES
There are four different types of plate boundary
Destructive
Collision
Constructive
Conservative
DESTRUCTIVE PLATE BOUNDARIES
Oceanic plates move towards continental plate and is forced
underneath it
The oceanic plate is forced down causing severe earthquakes
Hot liquid rock (magma) rises, violent volcanic eruptions occur
as the friction and heat from the mantle melt rock.
COLLISION PLATE BOUNDARY
If two continental plates meet each other they collide
rather than one sinking beneath the other.…read more

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Geography [TOPIC 2 ­ RESTLESS EARTH (PLATE TECTONICS)]
VOLCANOES
Constructive Plate Boundaries
As the plates move apart, magma rises upward from the mantle to fill the gap. This adds new rock to
the spreading plate. Some of the magma may also be forced out to the surface through a vent. Some
volcanoes grow high enough to become volcanic islands.…read more

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Geography [TOPIC 2 ­ RESTLESS EARTH (PLATE TECTONICS)]
SUPER VOLCANOES
What is a super volcano?
A super volcano is a colossal volcano that erupts at least 1000km3 of material.
They do not look like a volcano as they are not cone shaped. Instead they are large depressions
called calderas (a collapsed magma chamber) often marked by a rim of higher land round the edges.…read more

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Geography [TOPIC 2 ­ RESTLESS EARTH (PLATE TECTONICS)]
Disadvantages
Explosions lead to
o Dangerous gases
o Loss of life
o Loss of homes, animals and crops
o Disease and fires
o Avalanches, mudflows and floods
o Loss of wildlife and vegetation
PREDICTING VOLCANIC ERUPTIONS
Before an eruption magma moves into the area beneath the volcano and collects in the
magma chamber. This movement of magma can produce small earthquakes.
Volcanic emissions may increase before an eruption.…read more

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Geography [TOPIC 2 ­ RESTLESS EARTH (PLATE TECTONICS)]
Case study: Chances Peak, Montserrat, 1995-97 - an LEDC
Montserrat is a small island in the Caribbean which is still a British colony. Many of the residents were
poor living in small villages and practicing
substance farming. Before the eruption the
population was 12000, half of the population
lived in the capital city Plymouth, in the south of
the island.
In July 1995, the Soufrière Hills volcano Chances
Peak erupted for the first time in 350 years.…read more

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Geography [TOPIC 2 ­ RESTLESS EARTH (PLATE TECTONICS)]
An exclusion zone was set up in the volcanic region.
A volcanic observatory was built to monitor the volcano.
New roads and a new airport were built.
Services in the north of the island were expanded.
EARTHQUAKES
Earthquakes are vibrations caused by the earth's movement. They can occur at all four
major plate boundaries but the most severe earthquakes are normally found at
conservative and destructive plate boundaries.…read more

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Geography [TOPIC 2 ­ RESTLESS EARTH (PLATE TECTONICS)]
Where the focus is;
o A shallow focus will cause more damage and deaths as it is nearer the surface,
The magnitude of the earthquake on the Richterscale
Grounds made of sands and clays vibrate more causing more damage.…read more

Comments

daisy


VERY GOOD!!! i only wish that you do the coastal zone aswell :( - i would get a whole matching set ;) thanks x

trying4law

Perfect notes - brilliantly laid out! Such a shame I did completely different case studies...WHY IS MY SCHOOL DOING DIFFERENT THNGS TO EVERYONE ELSE?? but still, thank so much!

Isha112

These notes are awesome! Your notes taught me better than my school did!

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