GEOGRAHPY RESTLESS EARTH
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What is a 'plate'?
A section of the earth's crust
What is a plate margin?
The boundary where two plates meet
What is the earth's crust?
The outer layer of the earth
What is the mantle?
The dense mostly solid layer between the outer core and the crust
What is convection current?
The circular currents of heat in the mantle
Is oceanic crust or Continental crust thicker?
Continental crust is thicker. The thickest point is around 65km thick.
If two margins are pulling apart is that constructive or destructive?
That is a constructive margin.
If two margins are pushing together is that a constructive or a destructive margin?
Name the six major tectonic plates on the earth
- Pacific plate
- North American plate
- South American plate
- African plate
- Eurasian plate
- Indo-Australian plate
What are sub-marine explosions?
Volcanic eruptions that occur under the sea and will eventually build up to form islands eg Iceland
What is a conservative plate margin?
- Two plates being forced to slide past each other.
- Earthquakes occur where the plates 'stick' and friction is built up until it is suddenly released
What are fold mountains?
Large mountain ranges where rock layers have been crumpled as they have been forced together
What are ocean trenches?
Deep sections of the ocean, usually where an oceanic plate is sinking below the continental plate
What is the MEDC case study for fold mountains?
The alps, which form a natural boundary between Italy and neighbouring countries (such as France)
What is transhumance?
The act of taking livestock to higher pastures during the summer months (happens on the alps)
Where can a destructive plate boundary be found?
Where a continental plate meets an oceanic plate
Give an example of a conservative plate boundary
The San Andreas Fault in California
Give an example of a constructive plate boundary
The mid Atlantic ridge between the North American and Eurasian plates
How have the Himalayas been formed?
By the Indo-Australian plate colliding with the Eurasian plate.
What is the case study for fold mountains in an LEDC?
- The Himalayas
- (as the specification says only one example is needed this one is the best one to use and should be used.)
How many people live on the Himalayas?
At least 29 million (the mountains cover over 90% of Nepal)
In which fold mountains can Mount Everest be found?
The Himalayas. The mountain itself is in Nepal, and the longest staying tourists travel there for Everest
What percentage of Nepalese work is farming?
What are subsistence farmers?
Farmers who only grow enough to feed themselves and their family
What things are needed in order to generate Hydroelectric power?
- Heavy rainfall
- A constant supply of water
- A dam
What is magma?
Molten rock, gases and water held within a volcano
What is lava?
Magma that has been emitted from a volcano and the superheated steam and gases have escaped
What is a dike?
The vertical intrusion within a volcano other than the main vent
What is a sill?
The horizontal intrusion of magma within a volcano
Name four gases are released when a volcano explodes
- Carbon dioxide
- Sulphur dioxide
- Hydrogen chloride
- (These are just a few)
What is a volcanic vent?
An opening allowing the passage of air
What is an ash cloud?
The powdery residue top left after burning
What is a volcano's flank?
The side of the volcano
What is a volcanic crater?
The mouth of a volcano
What is a volcanic summit?
The volcano's highest point
What is a volcanic throat?
The entrance of a volcano
Are shield volcanoes found at constructive or destructive plate margins?
Constructive (they rise up as the plates are pulled apart)
Are composure cone volcanoes found at constructive or destructive plate margins?
Destructive (these volcanoes are a lot taller as the plates are pushing together)
What are the characteristics of a composite cone volcano?
- Talk cone
- Narrow base
- Steep sides
- Irregular dormant periods
Give an example of a composite cone volcano
What are the characteristics of a shield volcano?
- Wide base
- Gentle slopes
- Made of lava only
- Frequent eruptions
Give an example of a shield volcano
Hekla in Iceland
Is it composite or shield volcanoes that have more violent explosions?
Composite volcanoes have more violent explosions
What factors effect the impact of a volcanic eruption?
- Population in nearby area
- How prepared people are for an eruption
- How aware people are that an explosion will happen
- Type of magma
- LEDC or MEDC
What is the case study for a volcanic eruption?
Mount Nyiragongo in the Democratic republic of Congo
When did mount Nyiragongo explode?
January 17th 2002
How many villages were destroyed when mount Nyiragongo exploded?
Where are the majority of ocean wenches found?
Around the sides of the Pacific Ocean
What physical factors make it difficult for people to live on fold mountains?
- Climate - the higher you go the colder and wetter it gets (more snow as well)
- Accessibly - no transport such as roads or railway, dangerous to travel because of frequent rock fall
- Relief - the land is high and steep, little flat land for farming or building settlements
- Soil - typically stony, thin and infertile
What powers the movement of tectonic plates?
Heat from within the core of the earth
What are super volcanoes?
Super volcanoes are much larger volcanoes which would have devastating global consequences if one were to erupt. The location of all super volcanoes is unknown.
What do super-volcanoes cause?
- Depression of rock
- Rising magma contain gases which build up (causing land to be pushed up)
What do tiltmeters do?
Identify small, subtle changes in landscape
What do GPS systems do?
Use satellites to detect movement as little as 1mm
How can photography be used to monitor volcanoes?
Cameras can be places on the edge of craters and photograph at regular intervals to see changes
What do seismograms do?
Pick up movement in the ground
What is an example of a super volcano?
- Yellowstone, USA
- Which last erupted 630,000 years ago
What is a caldera?
The depression of the super volcano making the collapsed magma chamber
What are fissures?
Extended openings along a line of weakness that allow magma to escape
What is geothermal water?
Water that has been heated beneath the ground that comes to the surface in a variety of ways (such as steam)
What is a geyser?
A geothermal fissure in which water erupts into the air under pressure
In which hemisphere are super volcanos generally found in?
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