Plate Techtonics Flashcards
4 layers do the earth
Inner core
Outer core
The mantle
The crust
Inner core
Centre of the earth and hottest part Inner core is SOLID Made of iron and nickel Temperature of 5500° Immense heat energy, like engine room of the earth
Outer core
Layer surrounding inner core
LIQUID layer
Made of iron and nickel
Extremely hot, temperature around 5500°
The mantle
Widest section of the earth
Diameter approx. 2900km
Made of SEMI-MOLTEN ROCK called MAGMA
Upper parts = hard. Lower parts = soft and beginning to melt
The crust
Outer layer of earth
Thin layer between 0 - 100km thick
SOLID rock layer - where we live
2 types - continental = carries land
- oceanic = carries waterWhat is a plate boundary?
The point where 2 plates meet
What happens at a constructive boundary?
2 plates move apart
Plates are pushed apart by convection currents that rise up from within the mantle
Magma rising up in the gap + breaks through to form new crust
Mostly found underwater
Constructive boundary example
Mid Atlantic Ridge
North American plate and Eurasian plate
What happens at a destructive boundary?
Found where a continental plate meets an oceanic plate.
When they meet the OCEANIC PLATE is FORCED UNDER the CONTINENTAL PLATE because it’s more dense ( heavier ).
The friction caused can lead to severe earthquakes.
When the oceanic plate sinks into the lower crust and mantle it melts and forms magma.
The magma will be forced up through cracks in the crust by pressure and creates a volcano and these can be explosive.
SUBDUCTION ZONES ( OCEAN TRENCHES ) are found here
Destructive example
Oceanic crust - Nazca plate ( near Pacific Ocean )
Continental plate - South American plate
What happens at a Conservative boundary?
Plates more horizontally past each other.
This means no crust is created or destroyed.
Frequent earthquakes can happen here.
Conservative boundary example
SAN Andreas Fault In California.
Pacific plate moving northwestward by 6cm per year.
North American plate moving northwestward by 1cm per year.
What happens at a collision boundary?
Occurs when 2 plates of the same type push (collide) into/against each other.
They are the same type and therefore the same density.
Means one won’t sink below the other.
As a result they BUCKLE-UPWARDS and form fold mountains.
There are frequent earthquakes here.
Collision boundary example
The Himalayas Indian plate (continental crust) Eurasian plate (continental crust)
Continental drift
250 million years ago, most of the worlds land mass was joined together forming a super continent - PANGAEA.
In 1912 Alfred Wegener (German meteorologist) proposed the earth’s land masses were slowly moving apart - a theory he called CONTINENTAL DRIFT
