Earthquakes, Volcanoes, and Mountain Building. Tectonic Plate Boundaries Convergent: Tectonic plates collide Divergent: Tectonic plates move away from.
Post on 21-Jan-2016
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Earthquakes, Volcanoes, and Mountain Building
Tectonic Plate Boundaries
• Convergent: Tectonic plates collide
• Divergent: Tectonic plates move away from one another
• Transform: Tectonic plates slide past each other horizontally
Mountain Building• Mountains are
landmasses that rise well above Earth’s surface.
• Mountains form at convergent boundaries. – Two continental
plates of equal densities collide and push up the land• Earth’s crust folds
and breaks as a result
Earthquakes• Earthquakes are
the shaking movement of Earth’s surface.
• Earthquakes occur at transform boundaries. – The boundaries of
two plates move against each other
– Pressure is built up, causing a violent shift• This movement
causes an earthquake.
Volcanoes• Volcanoes are mountains that form
when magma is forced to Earth’s surface
• Volcanoes form at convergent boundaries, divergent boundaries, and hot spots.
Volcanoes at Convergent Boundaries
• When two plates collide, the denser one subducts beneath the less dense one.– The denser plate
that goes under melts and forms magma• This magma can be
forced through vents to form volcanic mountains.
Volcanoes at Convergent Boundaries
Example: Mount Etna, Ring of Fire volcanoes
Volcanoes at Divergent Boundaries• Two plates beneath the ocean can
move apart– A vent is exposed and magma slowly
rises to the surface• New oceanic lithosphere is formed
• This process is called sea-floor spreading
Volcanoes at Divergent Boundaries
Example: Iceland’s volcanic islands
Volcanoes at Hot Spots • A hot spot is a
place beneath the earth where very hot magma exists.–When a plate
moves over a hot spot in the mantle, a vent can be exposed• Fountains of
magma punch through the crust
Volcanoes at Hot Spots
Example: The Hawaiian Islands
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