6. Plate Tectonics

Part of

Today we are going to find out some more interesting facts about the plates that make up the Earth's outer layer that are actually moving! They are very large and move exceptionally slowly as we found out yesterday.

When they move like this it is known as Plate Tectonics!

What happens when they bump together - lets find out...

The outer shell of the Earth - the crust or lithosphere - which we heard about on Tuesday - is broken up into these major sections called tectonic plates.

The idea behind plate tectonics is that Earth used to be one large landmass but over many millions of years it separated and now there are large pieces (plates) on the surface of the Earth. The plates are like the skin of the planet. You can think of them like a giant jigsaw puzzle that covers the Earth underneath the ground. They constantly move around. Although constantly moving its actually only centimetres each year. You couldn't sit down and watch it happen. Or can you? This movement causes all kinds of things to happen, such as volcanoes, earthquakes, and tsunamis as they bump into one another.

Watch the video to find out more...


Volcanoes are formed when heavier tectonic plates collide with and slide underneath lighter tectonic plates. Think of it like pushing 2 biscuits together – one of them will usually go over the top of the other.

The lighter tectonic plate that goes on the top then begins to melt into magma as it pushes up. This magma will slowly harden and pile on top of itself, forming a volcano.

We will learn more about this below...


How do we know this is true and how can we actually tell if they have moved?

Look closely at this map showing what is called the Mid Atlantic Ridge - an entire line of ridges caused by the plates moving - you can see the split right down the middle of the ocean floor. This is where magma from the mantle has reached the seafloor erupting as lava and creating this new layer!

Now look at the edges of Africa and South America - do you think they could fit together?

Read the next section to find out more...

List of Tectonic Plates
List of Tectonic Plates (Larger Image)
Atlantic Bathymetry - Mid-Atlantic Ridge
Mid-Atlantic Ridge
Name The Continents Activity
Name The Continents Activity (PDF)
Answers (PDF)

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