Plate Tectonics
Storyboard Text
- In 1912, Alex Wegener proposed his theory that the continents were all once a supercontinent called Pangea, and that they had broke up and spread apart. He thought this because the he found that the continents went together like a puzzle, and there were fossils of the same animals on different, far continents. His theory was called Continental Drift. However, many people did not believe his theory. He later died and was buried in Greenland.
- Some years after Wegener's death, a new idea was proposed that the earth's surface is broken into plates that move. This theory is called Plate Tectonics.
- The data that helped create the theory of plate tectonics was in the 1950's and 1960's. The data was a map of the seafloor which showed a large range of mid-ocean ridges which outlined the continents. The ridges were the outcome of molten lava from the asthenosphere. This lava would cool and make a new crust, spreading the seafloor apart. This crust would eventually subduct millions of years later. This is the process of seafloor spreading.
- There are three different types of plate boundaries. One of them is the convergent boundary. The plates go together, destroying crust and creating mountains and volcanoes.
- Another is the divergent boundary. The plates pull apart and magma comes up to create new crust. Divergent boundaries can create mid-ocean ridges.
- The final boundary is the transform boundary. This occurs when the plates slide past each other and they can create earthquakes.
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