Plate Tectonics: Lesson for Kids

Instructor: Betsy Chesnutt

Betsy teaches college physics, biology, and engineering and has a Ph.D. in Biomedical Engineering

The surface of the Earth is always moving, although very slowly. Plate tectonics explains how the continents have moved over time and what causes many earthquakes and volcanoes. In this lesson, learn even more about plate tectonics!

Let's Look Beneath the Surface

Go outside and put your hand on the ground. Can you feel it moving? Even though the ground may seem motionless to you, it's really not! The surface layer of the Earth is always slowly moving. But how can the surface of the Earth move when it seems to be solid, you ask? To understand what's going on, we need to look beneath the surface.

The outer surface of the Earth that you can see and touch is called the crust, but just under the crust is a very hot region called the mantle. The mantle is SO hot that the rocks inside it have melted and turned into magma!

Because the mantle is mostly liquid, and the crust is solid, the crust floats on top of the mantle in much the same way that a leaf floats on top of a pond. As the liquid magma in the mantle moves, it carries big pieces of the crust, known as plates, with it.

The current shapes of the plates that make up Earth
plates and boundaries between them

Although it happens really slowly, over time the plates move due to the motion of the liquid magma in the mantle. Continents come together and break apart again. Islands rise and fall, and mountain ranges are pushed up when plates run into each other. Plate tectonics is the scientific theory that explains how these plates float on the mantle and move around the earth.

Scientific Proof Supporting Plate Tectonics

Because of plate tectonics, about 300 million years ago, most of the land in the whole world, including the land that makes up the modern day continents, was joined together into one large supercontinent called Pangaea. Over time, the continents moved apart, eventually reaching their current locations. In the future, they will continue to move, sometimes joining together and then splitting apart again!

How do we know this is true? Scientists have found lots of similar fossils in locations that are now very far apart, like South America and Africa. At one time, animals must have been able to freely cross between these continents, so there couldn't have been a big ocean between them like there is today!

Scientists know that many years ago some continents were touching each other because the fossil record shows that animals could move freely between locations that are very far apart today.
fossil evidence of continental drift

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