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This is planet Earth. The surface of Earth may look like its all in one piece but it's
not. It's actually made up of several pieces called plates. Let me explain.Okay so if you
cut the Earth in half this is what it would look like. The Earth is made up of four main
layers like a big round cake. The inner layer is called the inner core which is a hard ball
of hot metals. Around the inner core there's the outer core which is made up of very hot
liquid metals. Then there's the mantle which is made up of really hot melted rock, called
magma. Sometimes, magma will come to the surface as lava in volcanoes. The fourth layer is
called the crust. Like the crust of a piece of toast, the crust of the Earth is the hardest
and outermost layer of the Earth. We live on the crust. The crust is not a perfect ball.
It is broken up into many pieces called plates. These plates fit together like puzzle pieces
around the Earth. Now if you look at the map you can see where the plate boundaries are.
These plates are called Tectonic Plates and these Tectonic Plates can move. This is the
world today and this is what Scientists think the world looked like 300 million years ago.
This land mass is called Pangea. Over time the plates moved slowly apart. They moved
at about the speed that your fingernails grow so it took a very long time for them to get
to their present positions. Remember the Mantle from earlier? Well, the mantle is the layer
of Earth right below the Crust and it is made of hot melted rock. This melted rock moves
around the mantle and since it's right below the crust; when the mantle moves, the Tectonic
Plates of the crust moves as well. The plates move in three ways. They converge, that means
come together. When this happens one plate subducts, or goes under, another plate and
it melts back into the mantle. This happens very slowly, again about as slow as your fingernails
grow. And it happens mostly in oceans so you don't have to worry about any land being subducted
any time soon. When two continental or land plates collide they form mountains. This is
how the Himalayan Mountain Range was formed in India. The tallest mountain in the world
formed when two plates crashed together and crumpled up. Sorta like how a car crumples
when it hits something big. The second way that plates interact is it divergent boundaries.
This is where plates diverge, or move apart. And this is also how oceans form. As Pangea
began to break up and the Americas began to move farther away from Africa the Atlantic
Ocean formed in between the continents as the plates diverged. In the middle of the
Atlantic Ocean you can see the Mid-Atlantic Ridge. This is where the North American and
Eurasian Plates meet and this is where they are being moved apart. Here, new ocean crust
id formed which pushes the Americas and Europe about one inch farther apart every year. The
third way that plates can interact is at Transform faults. A transform boundary is when two plates
are not moving together, converging, and they're not moving apart, diverging. Instead these
plates simply slide next to each other. This is happening in California right now along
the San Andreas Fault line. This is why there are so many earthquakes in California. When
the two plates rub together, they shake the ground and make earthquakes. Okay, so let's
review. The Earth is made up of layers and the top layer is called the crust. The crust
is broken down into Tectonic Plates which very slowly move around the Earth because
of movement in the mantle, which is the hot layer of melted rock under the crust. The
plates move together at convergent boundaries, they move apart at divergent boundaries and
they slide past each other at transform boundaries. The movement of the plates is extremely slow
and there is very little change every year. But over millions and billions of years, you
can see big changes in the way the Earth looks. We know all of this because of great scientists
who dedicated their lives to researching and trying to learn more about this great planet
we call home.