Tectonics Flashcards
What is the difference between the crust and the mantle?
Crust- This is the thinnest layer of the Earth
. It is between 8 and 40KM thick. In comparison to the whole Earth’s radius, the crust is very thin, like an egg shell.
. Its thinner under the oceans than it is on land
. It contains rocks and minerals
Mantle- This is the thickest layer of the Earth.
. This is made of solid rock
. It moves in big, slow circles caused by convection currents
What is the difference between Continental and Oceanic Crust?
Continental Crust- Continental Crust is less dense than Oceanic Crust
Continental Crust is under land
Continental Crust is older, lighter and cannot be destroyed
Continental Crust is typically 30-50 KM thick
Oceanic Crust- Oceanic Crust is typically 5-10 KM thick
It is denser and can be sub-ducted
It is constantly being destroyed and replaced at plate boundaries
What is a destructive plate boundary also called?
A destructive plate boundary is sometimes called a convergent or tensional plate margin
What causes a destructive plate boundary?
It occurs when oceanic and continental plates move together.
What happens at a destructive plate boundary?
The oceanic plate is forced under the lighter continental plate. Friction causes melting of the oceanic plate and may trigger earthquakes
Magma rises up through cracks and erupts onto the surface.
What causes Collision Zones?
Collision zones form when two continental plates collide
What happens at a Collision Zone?
Neither plate is forced under the other, and so both are forced up and form fold mountains
What is a Constructive plate boundary also called?
A Constructive plate boundary is sometimes called a divergent plate margin.
What causes a Constructive plate boundary?
It occurs when plates move apart.
What happens at a Constructive Plate boundary?
Volcanoes are formed as magma wells up to fill the gap, and eventually new crust is formed.
What is a Conservative plate boundary also called?
A conservative plate boundary is sometimes called a transform plate margin
What causes Conservative plate boundaries?
They occur where plates slide past each other in opposite directions, or in the same direction but at different speeds
What happens at a Conservative plate boundary?
Friction is eventually overcome and the plates slip past in a sudden movement. The shockwaves created produce an earthquake.
What are convection currents?
Heat rising and falling inside the mantle creates convection currents generated by radioactive decay in the core. The convection currents move the plates.
How do plates move apart?
Where convection currents diverge, plates move away from each other
