Structure of the Earth

Earth Structure and Composition

The Earth’s structure consists of three parts, the crust, mantle and core. The crust is on the outside, while the mantle is in the middle and the core is the innermost section. The core is divided into two parts, the inner core and the outer core.

The structure of the Earth is similar to that of an egg. The Earth’s crust is like the shell of an egg, its mantle is like egg white and the core is like yolk.

What is Earth made of?

The Crust

The crust is found beneath mountain ranges and can be as thick as 40 kilometres. However, the Earth’s crust under oceans is only about 8 kilometres thick.

The Mantle

Parts of the Earth’s mantle are made up of hot rock, so they melted. This molten rock seeps through cracks in the crust and pours out of volcanoes. This is called lava. When the lava cools down, it turns into stone.

The Core

Scientists believe that the Earth’s core is mostly made up of iron. They feel that the inner core is solid while the outer core is in a liquid state.

How are Mountains Formed?

The crust and the rocky upper layer of the mantle are together called the lithosphere. The lithosphere consists of huge plates that move very slowly. These plates may collide, pull apart or even grind against each other. When these plates collide, one slips beneath the other and this pushes up mountains and forms trenches in oceans.

Interesting Facts about Earth

Scientists understand the composition of the Earth’s interior better by studying seismic waves. Seismic waves are vibrations that spread out from the epicentre of earthquakes. Their strength is measured and recorded when they reach the Earth’s surface. These waves have also revealed that the lithosphere, (which consists of plates that move as a result of convection currents in the mantle) is about 100 kilometres thick. The mantle is 2,900 kilometres thick. The core’s temperature ranges from 4,000 to 6,000 degrees Celsius, according to estimates.

Things To Do

• What kind of rocks are found in the mantle?
• The oceanic crust is made up of two primary metals. Name them.
• Apart from using seismic waves to identify the structure of the Earth, what other techniques are used to do the same?

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