2 Alfred WegenerEvidenceHypothesis – continental driftEarth’s continents were once joinedSuper Continent called PangaeaFossilsClimategeology
3 FossilsClimateGeologyMesosaurus – found on the west coast of Africa and the east coast of South AmericaIce scratches on South AmericaTropical plant fossil in GreenlandRocks that make up the continentsNorth America lines up with Scotland
4 TheorySea Floor EvidenceEvidence and explanations lead to the Theory of Plate TectonicsSea Floor SpreadingAge of the Sea FloorTrenches
5 Sea Floor SpreadingAge of the Sea floorRidges form on the sea floorAs the plates move apart molten rock pushes upCalled spreading centersMid-Atlantic RidgeThe rocks are older the further you move away from the spreading centers
6 Ocean TrenchesSize of earthDeep canyons on the ocean floorDense crust is sinking into the asthenosphereEarth isn’t changing size because at the same rate that new crust is forming (at spreading centers), old crust is being destroyed (at trenches)
7 How does it happen? Convection Currents Hot molten rock rises Cooled rock sinksMoves the tectonic plates like a conveyer belt
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