Chapter 2: The Earths Surface Flashcards
The structure of the earth
Crust
Mantle
Outer core
Inner core
A plate with land on top
Continental plates
A place with oceans on top
Oceanic plate
The line where two plates meet
Plate boundary
Convection Currents
- When mantle is heated in the mantle, it rises towards the crust
- As it rises it cools and moves sideways. This causes friction between the magma and the crust and pulls the plate.
- The magma cools and sinks back down into the mantle
- This process is constantly repeated
Who came up with plate tectonics
Alfred Wegener
The huge land mass 225 million years ago
Pangaea
Whats the terms for plates colliding
Convergent plates
Whats the term for plates that seperate
Diverging plates
Whats the term for sliding plates
Transform plates
Mid ocean ridge
Causes by diverging plates in the ocean allowing magma to cool and harden forming a ridge of rock
Volcanic islands
Causes by diverging plates allowing magma to pass through and harden forming an island.
Volcanic mountains
Magma can rise up from a magma chamber in the Earths crust through a vent. Lava, hot ash and rocks are thrown into the air. As more eruptions occur layers of material build up and a cone-shaped mountain is formed
An example of an active volcano
Mount St Helens in the USA
Example of a dormant volcano
Misti in Peru
Examples of an extinct volcano
Croghan hill in Co. Offaly
Positive effcts of a volcano
- Good for agriculture, fertile land
- Tourist attraction
- Geothermal energy
Negative effects
- Sulfur dioxide, poison people, and acid rain.
- Loss of human life
- When volcanic materials mix with water it forms a river of mud called a lahar. It destroys towns and villages
Instrument for measuring earthquakes
The Richter Scale, it ranges from 1-10. Each unit is 10 times stronger than the one before.
Damage caused by earthquakes
Loss of life
Buildings damaged
Electricty lines damaged may causes fires
Damage to sewers may causes disease
Bridges, roads and railways damaged, often making it difficult to get help.
Landslides and avalanches can be triggered
Earthquake in the sea creates a tsunami.
How to reduce the damage causes by earthquakes
Build earthquake-resistent buildings
Conduct earthquake and tsunami drills
Put early-warning systems
Fold mountain formation
When a heavier plate and a lighter plate are pushed against eachother and collide, the heavier plate sinks into the magma and the lighter plate then is forced upwards, causing a fold mountain to form.
The magma formed from the heavier plate melting into the mantle can move to the surface, forming volcanoes.
