The Theory of Plate Tectonics (How the Earth's crust moves)
The Earth's crust is divided up in to a number of plates, much like a jigsaw. These plates are resting on the liquid rock of the mantle. This liquid rock is constantly moving causing the plates to move. It is moving in response to the fluctuating levels of heat within the Earth's mantle. This process is referred to as convection currents. These plates can collide or separate depending on the movement on the magma.
Colliding plates
One plate is dragged beneath the other
Fold mountains and volcanic mountains can form here
Earthquakes can occur here
Separating plates
Both plates are moving away from each other and magma can seep through the gap
Volcanic islands and mid-ocean ridges can form here
Folding
When two plates collide the land they are carrying compresses and buckles upwards. This forms fold mountains which are some of the highest mountain ranges in the world. These include the Alps, the Andes, the Rockies and the MacGillycuddy's Reeks in Munster. The MacGillycuddy's Reeks were formed 250 million years ago and have been subject to the processes of weathering. This means these mountains are much smaller then the much younger (35 million years ago) Alps, Andes or Rockies.
Earthquakes
Earthquakes occur along plate boundaries when the plates are sliding past each other or converging. Tension builds up between the two plates and when this is released it causes a sudden jump in plate movement. This jump causes shock waves which can be felt on the Earth's surface.
The focus of an earthquake is where it occurs within the crust
The epicentre is where it is felt on the surface
Shock waves are the vibrations which are released by an earthquake
A seismograph measures earthquake activity
The Richter Scale measures the intensity of an earthquake or the magnitude
The Earth's crust is divided up in to a number of plates, much like a jigsaw. These plates are resting on the liquid rock of the mantle. This liquid rock is constantly moving causing the plates to move. It is moving in response to the fluctuating levels of heat within the Earth's mantle. This process is referred to as convection currents. These plates can collide or separate depending on the movement on the magma.
Colliding plates
One plate is dragged beneath the other
Fold mountains and volcanic mountains can form here
Earthquakes can occur here
Separating plates
Both plates are moving away from each other and magma can seep through the gap
Volcanic islands and mid-ocean ridges can form here
Folding
When two plates collide the land they are carrying compresses and buckles upwards. This forms fold mountains which are some of the highest mountain ranges in the world. These include the Alps, the Andes, the Rockies and the MacGillycuddy's Reeks in Munster. The MacGillycuddy's Reeks were formed 250 million years ago and have been subject to the processes of weathering. This means these mountains are much smaller then the much younger (35 million years ago) Alps, Andes or Rockies.
Earthquakes
Earthquakes occur along plate boundaries when the plates are sliding past each other or converging. Tension builds up between the two plates and when this is released it causes a sudden jump in plate movement. This jump causes shock waves which can be felt on the Earth's surface.
The focus of an earthquake is where it occurs within the crust
The epicentre is where it is felt on the surface
Shock waves are the vibrations which are released by an earthquake
A seismograph measures earthquake activity
The Richter Scale measures the intensity of an earthquake or the magnitude