Plate Tectonics

Continenetal Drift and the Theory of Plate Tectonics
1. The Jigsaw Theory (by Wegener): At some point all the continents were joined together in what is known as Pangea
2. The Mountain Theory (Wegener): On different continents there are the same mountain ranges (i.e. rock type and appearances) - Appalachian and Atlas Mountains
3. Fossil Type Theory (Wegener): Similar fossil types are found in different continents where there is no way that they could have travelled that distance or be found on that continent naturally
4. Paleomagentism: measures small variations in the Earths magnetic field and sea floor spreading. As magma rises it splits the polarising the rocks
Why are the plates moving?
1. Convection currents
2. Heat rises & cooler things fall - when magma becomes hotter and less dense it rises, reaching the crust to then cool and fall
3. The whole earth is pushing into the core, therefore the centre of the E is under the most pressure which makes it the hottest part of the earth
Theories of Convection Currents
1. 1. Plates floating on top of the convection current moving the plates
2. Ridge Push and Slab Pull
  1. a. When magma rises it solidifies and forms a ridge, it pushes the plate because of the ridge being formed
  2. b. There are other sections where bits of plate are sinking back into the mantle, as that plate is sinking it is pulling the rest of the plate down causing the rest of the plate to move

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	Erstellt von Caitlin McFadyen vor mehr als 8 Jahre