Investigating Planet Earth

Investigating Planet Earth

The Structure of the Earth-

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The Crust:

This region is thin compared to the other layers in the Earth. It

varies in thickness from 10km deep to 65km deep. The crust is made up

of lighter rocks that "float" on top of the mantle. This layer

includes the continents as well as the rock under the oceans. The

thickness of the crust might be a little deceiving... to put it into

perspective, we have built many deep mines but NONE have yet reached

the mantle!

The Mantle:

This region lies under the crust and is approximately 2900km thick.

The mantle is much denser than the crust (which is why the crust

floats on top) and has a texture much like tar. The rock in this

region is rich in compounds made from iron, magnesium, and silicon,

which accounts for why it is denser than the crust.

The Core:

This region is divided into two parts. The outer part is called the

Outer Core. It is about 2100km thick and made of liquid nickel and

iron. The inner part is called the Inner Core and it is the real

centre of the Earth. This part is about 2800km in diameter and is made

of solid iron and nickel.

Plate tectonics

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Plate tectonics are a reasonably new theory that has revolutionized

the way geologists thinks about the Earth. According to the theory,

the surface of the Earth is broken into large plates. The size and

position of these plates change over time. The edges of these plates,

where they move against each other, this causes earthquakes,

volcanoes, and mountain building. Plate tectonics is a combination of

two earlier ideas, continental drift and sea-floor spreading.

The Earth is made up of several of these different layers. The outer

layer is called the Crust. It is made of the lighter, less dense,

rocks that floated to the surface when the Earth was formed. The

deepest mine in the world is only 3.