The Earth

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Earth

Planet Earth

- Earth is made up of layers. the crust (made of rock and other minerals), the mantle (molten rock) and the core (an extremely hot mixture of iron and nickel).

- Earth has a very thin layer of air around it called the atmosphere.

- Much of the crust is covered by by water (the ocean).

- People used to think the Earth's core was very hot because of the heat left over from when the Earth was first formed.

What is the Earth like inside?

- The crust is a thin outer layer of cold, solid rock. It's thickness is between 5 and 30 kilometers.

- The mantle is made of very hot molten rock that flows very slowly by convection currents.

- The core is at the center; an inner core, in the center, is solid iron and nickle and the outer core is a molten mixture of iron and nickle.

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Continents on the move

Pangea, the super continent

- Alfred Wegener in 1915 suggested that all the continents were once joined together in a super continent he called Pangea. He had noticed that South America could fit into the side of Africa.

- Wegener suggested that the continents had drifted apart.

Continental drift

- When Wegener suggested his hypothesis, other scientists rejected it because no one could explain how huge continents could move. Later other scientists found evidence to support Wegener's theory.

- The Earth's crust and the semi-solid upper part of the mantle make up the lithosphere.

- The tectonic plates float on the liquid rock of the mantle. Heat from radioactive processes within the Earth drives convection currents in the mantle. These currents carry the floating plates, and the continents very slowly, only a few centimeters a year, in a process called continental drift.

-When two tectonic plates the size of continents collide they push the land upwards, forming mountains. The worlds largest mountain ranges are formed where continental plates collide.

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