Look closely at the images below of South America and Africa. Watch the animation to see how the images would fit together.
Look closely at the images below of South America and Africa. Watch the animation to see how the images would fit together.
In the early 1900s, a scientist named Alfred Wegener noticed how the continents seemed to fit together and developed the Theory of Continental Drift. Continental drift is the theory that continents can drift apart from one other and have done so in the past. Wegner's theory also explained why fossils of the same plant and animal species are found on both sides of the Atlantic Ocean. In addition, similar types of rock and evidence of the same ancient climatic conditions are found on several continents.
Wegner hypothesized that all the separate continents of today were once joined in a single landmass that he called Pangaea.
The theory of plate tectonics states that Earth's lithosphere is divided into tectonic plates that move around on top of the asthenosphere.
What causes the plates to move? Scientists are not sure but have possible answers, which all involve the plates being affected by heat and gravity. There are three possible driving forces of plate tectonics:
The diagram below shows the three possible driving forces of plate tectonics.
Click on each driving force for a description.
Source: adapted from: Possible Driving Forces of Plate Tectonics, Columbia University