Hhh Flashcards
What is the mantle
Semi molten rock that moves very slowly
How big is the earths crust
It is very thin, 20km
What is the crust divided into
Slabs called tectonic plates
What two types of crust are tectonic plates mad of
Continental and oceanic
What is continental crust like
Thicker and less dense
What is oceanic crust like
Thinner and more dense
Why do the plates move
The mantle underneath them is moving
What ia the place where a plate meets called
Boundaries or plate boundaries
What are destructive margins
Where two plates are moving towards each other
Where is an example of a destructive margin
East coast of japan
Explain what happens a destructive margin when a continental plate meets a oceanic plate
The denser oceanic plate is forced down into the mantle and destroyed. This often creates volcanoes and ocean trenches (very deep sections of the ocean floor where the oceanic plate goes down)
Explain what happens at a destructive plate margin when 2 continental plates meet
They smash together but no crust is destroyed
What are constructive margins
Where 2 playes meet moving away from each other. Magma rises from the mantle to fill the gap and cools creating new crust
What is an example of a constructive margins
The mid-atlantic ridge
What are conservative margins
Where 2 plates are moving sideways past each other or are moving in the same direction but at different speeds. Crust isnt created or destroyed
Where is an example of a conservative margin
Along the west coast of usa
How are mountains formed
When techtonic plates collide the sedimentary rocks that have built up between them are folded and forced upwards to form mountains
Where are fold mountains found
At destructive plate margins and places where there used to be destructive margins
Where are some fold mountain
West coast of north america
Why do you get fold mountains
Because a continental plate collides with an oceanic plate or when 2 continental plates collide
How were the andes formed
When a continental plate collided with an oceanic plate
How were the himalayas forme d
When 2 continental plates colide
What are fold mountains like
Very high mountains which are rocky with steep slopes, often with snow and glaciers in the highest bits and lakes in the valleys between the mountains
Why are fold mountains used for farming
They aren’t good for growing crops so they’re used to graze animals. Lower slopes are used to grow crops. Steep slopes are sometimes terraced to make growing crops easier
Why are fold mountains used for hydroelectric power
The steep sided mountains and high lakes make fold mountains ideal for generating power
Why are fold mountains used for mining
They are a major source of metal ores. The steep slopes make access to the mines difficult so zig zag roads have been craved pit on the sides of mountains to reach them
How are the mines in the fold mountains made accessible
The steep slopes make access to the mines difficult so zig zag roads have been craved pit on the sides of mountains to reach them
How are fold mountains used for forestry
Theu are a good environment to grow some tyoes of tree. They’re grown on the steep valley slopes and are used for things like fuel, building materials and to make paper and furniture
How are fold mountains used for tourism
They have spectacular scenery which attracts tourists. In winter people visit for skiing, snowboarding and ice climbing. In summer walkers come to enjoy the scenery. Tunnels have been drilled through some fold mountains to makr straight fast roads. This improves communications for tourists and people who live in the area as its quicker to get to places.
How are volcanoes formed at destructive plate margins
The oceanic plate moves down under the continental plate because its more dense into the mantle where it is melted and destroyed
A pool of magma forms
The magma rises through cracks in the crust called vents
The magma erupts onto the surface( where it is called lava) forming a volcano
