How do plate tectonics shape our world Flashcards
What are the two crusts?
Oceanic crust-dense and 5-10km thick beneath the oceans
Continental crust- less dense and up to 70km thick under the continents
What is the earth’s structure in order of closest to furthest
Crust
Mantle
Outer core
Inner core
What is the mantle
Hot,dense, molten rock-2900 km thick
The top layer and crust make up the rigid tectonic plates of the lithosphere
Temperature and density increases towards the centre
What is the outer core?
Semi liquid metallic rock-2250km thick
What is the inner core
Solid metallic rock- 1200km
Temperatures can reach 6000degrees
Fact
Tectonic plates slide by each other at conservative boundaries separate at constructive boundaries and collide at destructive boundaries
the conservative boundary?
Two plates slide past each other at different rates
Friction between the plates build stresses and trigger shallow focus earthquakes when they slip
There are no volcanoes because there is no magma
WHat is a Constructive plate boundary
Where two plates move apart creating a new oceanic plate
As it breaks the crust it causes mild, shallow focus earthwuakes
Magma is very hot and fluid which results in shield volcanoes
What is a Destructive plate boundary
Where two plates move towards each other
destroying the oceanic plate
The oceanic plate is subducted beneath the less dense continental plate
Friction causes strong deep focus earthquakes
This creates gas rich magma resulting in steep sided composite volcanoes
What is a hotspot
Places where magma rises in the mantle may form a shield volcanoe
Collision boundaries
Where two continental plates meet there is no subduction so no magma to form volcanoes howveer they create mountains and powerrful shallow focus earthquakes can be triggered
What are convection currents
Flows of heat rising from the earths core spreading cooling and sinking again
