The Plate Tectonics Model

• Plate tectonics is the study of the movement of plates and of the land forms that result.
• In 1912 Alfred Wegener put forward the Theory of Continental Drift.
• Alfred Wegener suggested that the continents once formed a single landmass called Pangaea.
• About 200 million years ago Pangaea began to break apart.
• After Pangea began to break apart two Continents formed called Laurasia and Gondwanaland.
• Gradually over millions of years the continents drifted into their present position.
• • The earth's crust is made up of 7 large plates and several smaller ones.
• Plates float on the semi-molten rock of the mantle.
• Convection Currents in the mantle cause the magma to rise, cool, flow sideways and sink.
• As a result of the convection currents plates which float in the mantle are constantly moving.
• The earth's plates constantly moving is known as the Theory of Continental Drift.
• How do we know Continental Drift occurred?

  Fossil evidence, matching coastlines, and geological formations.
• In the Twentieth century an American Geologist Harry Hess studied the sea floor from a submarine.
• Harry Hess proved that new crust is created as plates separate.
• Harry Hess' theory became known as Sea floor spreading.
• The theory of Continental Drift and Seafloor Spreading have been combined to create a new Theory known as Plate Tectonics.
• The Theory of Plate Tectonics recognises that a section of the earth’s crust is referred to as a Plate.
• Two plates meet at a Plate boundary.
• There are 3 different types of Plate Boundaries

  1. Constructive/Divergent Boundaries - plates separate
  2. Destructive/Convergent Boundaries - plates collide
  3. Neutral/Passive Boundaries /Transform Faults - plates slide past each other
• The Theory of Plate Tectonics explains the movement of plates through the process of convection in the Earth's mantle.
• The Theory of Plate Tectonics states that the Earth's lithosphere is divided into several large plates that move and interact with each other, causing earthquakes, volcanic activity, and the formation of mountains.
• The major components of the Theory of Plate Tectonics are the lithosphere, asthenosphere, and the movement of tectonic plates.