plate tectonics & continental drift

by: nathalie lara

the theory...

As Alfred Wegner stated, around the year 1915, all the continents in the world were all once one. The conjoined countries were called Pangea. Although Wegner claimed this was true in the early 1915, he didn't have much proof so it was not proved the the late 1900s. After Wegner had died.

After they found out it was true they began to fined out more things about the earth, like plate tectonics. Plate tectonics are ways that the crust is in a slow constant movement.

The types of plate tectonics

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tranform

This is the San Andrés fault in California. This tranform boundry is one of the only one that we can walk up to and see it closely. Tranform plate boundaries are when 2 plate tectonics are moving slowly past each other.
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divergent

This is an image of the treat African Rift Valley. Divergent plate boundaries are when two plate boundaries are slowly moving away from me each other.

convergent

There are 3 types of convergent plate boundaries.

Convergent- ocean to ocean is when 2 plates come together and crust is destroyed. The density of the plates determine which will sink. an example of that would be the Aleutians island in Japan.

convergent - ocean to continent is when ocean sinks under continent. These usually creat coastal volcanic mountain ranges. An example of this would be The cascades mountain ranges in Washington state.

The last type of convergent boundary is:

convergent- continent to continent is when 2 continents meet and fold together to creat mountains. In this process crust is neither created or destroyed. An example of this would be the Himalayas mountains in Asia.