Chapter 1 The Earth Flashcards
Mantle
Beneath the crust is a layer of hot, soft rock called the mantle
Crust
The crust is the earth’s outer skin and consists of solid rock
Core
The core (inner and outer) is at the centre of the earth. It is made of iron and nickel
Magma
The molten or semi molten material that makes up the earths mantle
Plate tectonics
The theory that earths crust is broken into a number of constantly moving plates is called plate tectonics
Plate boundaries
The plates appear to move at different speeds and in different directions. Even so, the whole jigsaw puzzle of plates is linked together
Destructive boundaries
When two plates collide, they build up huge pressure. The heavier plate is forced downwards into the mantle where it melts. Since some crust is destroyed this is called a destructive boundary.
Constructive boundaries
When plates pull apart, molten magma rises from the mantle, where it cools and new crust is formed. As a result this is called a constructive boundary.
Convection Currents
The very hot core heats the magma in the mantle. This sets up Convection Currents in the mantle. Molten magma moves upwards from the core to the crust. Here it cools and sinks back down towards the core, so that the cycle can start all over again
Pangaea
The continents began as one large landmass, called Pangaea. It gradually began to break up. The individual sections started to drift apart, carried along on the moving plates.
Continental Drift
The process with Pangaea is called Continental Drift. It still continues today, for example Europe is slowly moving away from North America, while India continues to push northwards into Asia.
Mid-ocean Ridge
A Mid-ocean Ridge is an underwater mountain range. It is formed where two plates separate.
Crater
The top of a volcano
Vent
Volcanic mountains are formed when molten magma emerges or erupts through a hole in the crust called a vent.
Magma reservoir
Magma Reservoir is and underground pool of liquid rock found beneath the surface of the earth.
Active
The volcano is still euruption at regular intervals,e.g. Mount Etna, Mount Vesuvius and Mount St Helens.
Dormant
The volcano has been quite for hundreds of years but may erupt again
Extinct
The volcano has not erupted in recorded times (thousands of years).
Earthquake
An earthquake is a sudden movement or trembling of the earths crust.
Fault line
The plates move along the fault line
Tremor
The tremors spread out from the focus
Focus
The focus is the point deep in the earths crust where the earthquake begins
Epicentre
The epicentre is the point on the surface directly above the focus. It is the place where tremors are strongest.
Aftershock
An aftershock is a smaller earthquake that occurs after a previous large earthquake, in the same area of the main shock. If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a foreshock.
