Plate tectonics
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Plate Tectonics. By Lydia Pillinger. Plate tectonics. The Earth's surface is made up of a series of large plates. These plates are in constant motion travelling at a few centimetres per year. The ocean floors are continually moving, spreading from the centre and sinking at the edges.

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Plate Tectonics

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Plate tectonics

Plate Tectonics

By Lydia Pillinger


Plate tectonics1

Plate tectonics

  • The Earth's surface is made up of a series of large plates.

  • These plates are in constant motion travelling at a few centimetres per year.

  • The ocean floors are continually moving, spreading from the centre and sinking at the edges.

  • convection currents beneath the plates move the plates in different directions.

  • The source of heat driving the convection currents is radioactive decay which is happening deep in the Earth.


The theory

The theory

  • The theory states that Earth's outermost layer, the lithosphere, is broken into 7 large, rigid pieces called plates: the African, North American, South American, Eurasian, Australian, Antarctic, and Pacific plates.

  • The plates move in different directions.

  • This means they can sometimes crash in to each other.

  • Where they meet is called a plate boundary.


Theory

Theory…

  • Plate tectonics is the theory thatEarth's outer layer is made up of plates, which have moved throughout Earth's history. In the past 25 years, scientists have developed a theory -- called plate tectonics -- that explains the locations of volcanoes and their relationship to other large-scale geologic features. The theory explains the how and why behind mountains, volcanoes, and earthquakes, as well as how, long ago, similar animals could have lived at the same time on what are now widely separated continents. Exactly what drives plate tectonics is not known.

  • One theory is that convection within the Earth's mantle pushes the plates, in much the same way that air heated by your body rises upward and is deflected sideways when it reaches the ceiling.


Types of plate boundaries

Types of plate boundaries

  • Convergent boundaries- crashing

  • Divergent boundaries- pulling apart

  • Transform boundaries- sidesweeping


How volcanoes come about

How volcanoes come about

  • How do volcanoes occur?

    When the earths plates pull apart causing magma to rise to surface. They can also occur when one plate dives beneath another, this also causes magma to rise to the surface. This is known as the subduction zone

Where do volcanoes occur?

They usually occur on the edges of the plates, near where earthquakes occur. Volcanoes occur around the edge of the pacific ocean called the ring of fire.


Different types of volcanoes

Different types of volcanoes

  • Shield- sloping form

  • Composite- sides are steep

  • Cinder cones- gentle moderate slopes


Earthquakes

Earthquakes

  • Sudden movements of the earths crust

  • Happens when the tectonic plates is subdued, pushed under or broken in half.

  • When this occurs energy is released shaking the ground


Measuring earthquakes

Measuring earthquakes

  • We measure earthquakes using the Richter scale


Epicentre of an earthquake

Epicentre of an earthquake

  • The earthquake epicenter is the point on the earth's surface directly above the focus. This is where the shaking is concentrated and usually the most damage is done.

  • Geologists use seismic wave charts to determine the earthquake epicenter


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