Continental Drift/ Seafloor Spreading

Continental Drift

Continental Drift is the theory that the continents were all connected at on time and have slowly moved to their current location. Scientist know this happened because of four reasons.

1. The continents look like they fit- Pangea is the theory that all of the continents were once connected. When they drifted apart the shapes of the continents looked like they still fit together. This tells scientists that continental drift could have taken place.

2. Fossils- When exploring the theory of continental drift, scientists found the same fossils on two different continents. This was strange because they fossils they found were from an animal that couldn't swim to get to a different continent. This means that continental drift must have happened.

3. Climate- There are signs of tropical plant life on Antarctica and signs of ice burgs in the tropics. You may ask how this is possible. Its because of continental drift. Antarctica was once in a warm area and hot continents were once in a cold area.

4. Landforms- There are also signs of different landforms that were once on one continent that "match up" with other landforms on different continents. The matching landforms can only be explained by continental drift.

Seafloor Spreading

Seafloor spreading is basically the spreading of the seafloor caused by a series of events. First magma from under the ocean comes up to the seafloor. When it touches the water the magma hardens and expands the seafloor. This new land is made at the mid-ocean ridges (a big underwater mountain range) and scientists can date the new land that is made.

An evidence of seafloor spreading is magnetic reversal. The new land is formed and it has a different magnetic field, which proves that seafloor spreading is taking place.

Here is a quick, interesting video on seafloor spreading.
https://www.youtube.com/watch?v=BCzCmldiaWQ

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