The Plate Tectonics Flashcards
What are the 6 layers of the Earth?
- Inner core
- Outer core
- Mantle
- Asthenosphere
- Lithosphere
- Crust
What is the inner core?
- Solid ball of iron/nickel
- Very hot due to pressure and radioactive decay (contains elements such as uranium that give off heat as they decompose)
- It is responsible for Earth’s internal energy and spreads throughout the Earth.
What is the outer core?
A semi-molten layer of iron/nickel surrounding the outer core.
What is the mantle?
- (mainly) solid rock high in silicon
(Above the outer core, below the asthenosphere)
What is the asthenosphere?
A semi-molten layer that constantly moves due to convection currents.
(Above the mantle, below the lithosphere)
What is the lithosphere?
- Broken up into plates
- Majority of the lithosphere is in the mantle
What is the crust?
The thin top of the lithosphere
Oceanic crust is ____ dense than the continental crust.
more
Continental crust is ____ dense than the oceanic crust.
less
What are the two types of crust?
- Oceanic
- Continental
What causes tectonic plates to move?
Convection currents
What causes convection currents?
Less dense magma rises, cools, then sinks
What are plate boundaries/margins?
Edges of where plates meet
What is a divergent plate boundary?
Plates move AWAY from each other
What happens to an oceanic and continental plate on a destructive plate boundary?
- Denser oceanic plate subducts below
the continental. - The plate subducting leaves a deep
ocean trench. - Fold mountains occur when sediment
is pushed upwards during subduction. - The oceanic crust is melted as it
subducts into the asthenosphere. - The extra magma created causes
pressure to build up. - Pressurised magma forces through
weak areas in the continental plate - Explosive, high pressure volcanoes
erupt through the continental plate,
(composite volcanoes)
What happens to 2 oceanic plates on a destructive plate boundary?
- Heavier plate subducts leaving an
ocean trench. Fold mountains will also
occur. - Built up pressure causes underwater
volcanoes bursting through oceanic
plate. - Lava cools and creates new land called
island arcs
What happens to two continental plates on a destructive plate boundary?
- Both plates are not as dense as
oceanic so lots of pressure builds. - Ancient oceanic crust is subducted
slightly, but there is no subduction of
continental crust. - Pile up of continental crust on top of
lithosphere due to pressure between
plates. - Fold mountains formed from piles of
continental crust
What happens to two oceanic plates on a constructive plate boundary?
- Magma rises in between the gap left
by the two plates separating, forming
new land when it cools. - Less explosive underwater volcanoes
formed as magma rises. - New land forming on the ocean floor by
lava filling the gaps (sea
floor spreading).
What happens to two continental plates on a constructive plate boundary?
- Any land in the middle of the separation
is forced apart, causing a rift valley. - Volcanoes form where the magma
rises. - Eventually the gap will most likely fill
with water and separate completely
from the main island.
What is ridge push?
- The slope created when plates move apart, with gravity acting upon it as it is at a higher elevation.
- Gravity pushes the plates further away, widening the gap
What is slap pull?
When a plate subducts, the plate sinking into the mantle pulls the rest of the plate (slab) with it, causing further subduction
What happens at a convergent plate boundary?
Plates move towards eachother (denser plate will subduct)
What happens at a transform plate boundary?
Plates slide past eachother
Name the three types of plate boundaries:
Divergent
Convergent
Transform
