After reading this lesson, you’ll learn what things scientists observe in the natural world that lead them to believe that plate tectonics is the way our continents were formed.
What Is Plate Tectonics?
Take a moment and look at a world map. Doesn’t it look as if the continents are puzzle pieces that fit together? For instance, doesn’t it look as if South America, Brazil, in particular, fits into the eastern border of Africa?
Fossils and Rocks
Second, when looking at the fossils found on the edges of the continents, scientists find that similar fossils are found on separate continents which points to the idea that these continents were once connected to each other as one giant continent called Pangea. The continents are now separated because the plates have moved over the years.For example, fossils of Cynognathus are found in South America as well as in Africa. The location where this fossil is found follows a path from the one continent to the other. The same is true of the fossils for Lystrosaurus.
This fossil can be found in Africa, India, and Antarctica.Scientists have also found that similar rocks are found in different continents and if you move the continents around so that the puzzle pieces seem to fit, then the rocks also match up. For example, the rock types found on the western coast of South America match up with the rock types found on the matching eastern cost of Africa.
Third, as mentioned before, the continents look like as if they are puzzle pieces that fit together.
South America matches up with Africa. India bends down to match up with Africa, and Antarctica fits in nicely under India and next to Africa. The western side of Antarctica tucks in nicely to the eastern side of Australia.As the plates move, of course, so will the continents.
Following the plate tectonic theory, the continents on the plates are still moving today, albeit very slowly. Imagine the world fast forwarding a few thousand or even a few million years, and you’ll see the continents have moved. Scientists won’t know exactly where the continents will end up, but they do know that the continents are moving slowly
Let’s review.The theory of plate tectonics says the continents are moving because the plates on which the continents are on are moving slowly over the molten mantle of the Earth.
Scientists believe in the plate tectonics theory because of the following pieces of evidence.
- First, the age of the crust is youngest at the plate boundaries where older rock is pushed up and the youngest rock stays on the bottom.
- Second, fossils of the same organism are found on different continents which points to the possibility that the continents were once connected before the movement of the plates moved the continents apart. Similarly, rock types match up at continent edges.
- Third, the continental shapes themselves look as if they are puzzle pieces that fit together.