The structure of the Earth


Magma is molten rock under the Earth’s surface. Lava is molten rock that escapes onto the Earth’s surface, for example from a volcanic eruption.

Volcanic eruptions

smoking volcano


Some eruptions produce runny lava, while others produce thick lava that escapes violently. Geologists study volcanoes to try to predict future eruptions, and to gather information about the Earth’s structure. Volcanoes can be very destructive, but some people choose to live near them because volcanic soil is very fertile. It contains minerals needed by plants for healthy growth.

Igneous rocks

rock is a mixture of black pink and white flecks

Crystals in igneous rock

Igneous rocks are made when molten rock cools down and solidifies. The slower the molten rock cools, the larger the crystals become. For example, gabbro has larger crystals than basalt because the molten rock that formed gabbro cooled more slowly.

Igneous rocks- Higher tier

Different types of igneous rocks form lava (molten rock on the Earth’s surface):

  • basalt is rich in iron - it formed from runny lava produced in a fairly safe volcanic eruption
  • rhyolite is rich in silica - it formed from thick lava produced in an explosive eruption.

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