The Restless Earth Flashcards
Name the layers of Earth from the inner layer to the outer layer.
Inner core, outer core, mantle, crust.
What is the mantle?
The layer around the core, which is semi-molten Rock that moves very slowly.
The crust is divided into lots of slabs called ______. They _____ on the mantle.
The crust is divided into lots of slabs called tectonic plates.They float on the mantle.
Plates are made up of two types of crust named what?
Continental (thicker and less dense), and oceanic (thinner and more dense).
Why do the plates move?
Because the rock in the mantle underneath them is moving.
The places where plates meet are called what?
Boundaries or plate margins.
Name the three types of plate margins.
Destructive , constructive and conservative.
What’s a destructive margin?
Where two plates are moving towards each other.
What happens when an oceanic plate meets a continental plate and they’re moving towards each other?
The oceanic plate is forced down into the mantle and destroyed. This can create volcanoes or ocean trenches.
What is the earths core made out of?
Solid iron and nickel.
What’s a constructive margin?
Where two plates are moving away from each other. Magma (molten rock) rises from the mantle to fill the gap and cools to create new crust.
What’s a conservative margin?
Where two plates are moving sideways past each other, or moving in the same direction but at different speeds. Crust isn’t created or destroyed.
How are fold mountains formed?
When plates collide the sedimentary rocks that have built up between them are folded and forced upwards to form mountains.
What are fold mountains used for?
Farming , hydro-electric power, mining, forestry , tourism.
What’s a composite volcano?
Made up of ash and lava that’s erupted, cooled and hardened into layers. The lava is usually thick and flows slowly. It hardens to form a steep-sided volcano.
What’s a shield volcano?
Made up of only lava. The lava is runny, flows quickly and spreads over a wide area forming a low, flat volcano.
What’s a dome volcano?
Made up of only lava. The lava is thick, flows slowly and hardens quickly, forming a steep-sides volcano.
How can you predict a volcano and what changes happen?
Things like tiny earthquakes, escaping gas, and changes in the shape of the volcano (bulges in the land where magma has built up underneath) can all mean that an eruption is happening soon.
Where do you find supervolcanoes?
They can be found in a handful of places around the world, at destructive plate margins or at very hot places over the mantle (hotspots).
How are supervolcanoes formed?
Magma rises up through cracks in the crust to form a large magma basin below the surface. The pressure of the magma causes a circular bulge on the surface.
How do supervolcanoes erupt?
The bulge cracks, creating vents for lava to escape through. The lava erupts out causing earthquakes.
What happens after a supervolcano has erupted?
As the magma basin empties the bulge is no longer supported so it collapses causing more magma to spew out. It leaves a big crater behind called a caldera where the bulge collapsed.
What will happen if a supervolcano erupts?
An eruption will throw out thousands of cubic kilometres of rock, ash and lava (much more than normal) , a cloud of superheated gas will flow at high speed burning everything, ash will block out almost all day light , and bury fields and buildings
What causes an earthquake?
Earthquakes are caused by tension that builds when plates are stuck together and when they eventually become unstuck it causes shock waves (vibrations)
