Volcanoes 9

BY MARTÍ I LUCAS 6é

A volcano is like a chimney in the Earth’s crust (surface) where magma flows out.

In 1883, in Indonesia, a volcano called Krakatoa erupted at first.

Krakatoa eruption

The inside of the Earth is very hot, and some of the solid rock melts to form hot liquid rock called magma. Eventually magma, gases and ash break through a hole in the earth’s surface. The hole is called vent. vent When magma leaves the vent, it becomes lava.

Explain how volcanoes form. Some volcanoes form above hot spot, which is a very hot place in the mantle

Contents: gas, dust, water vapour, lava, ash. Scientists put volcanoes into three groups: Active volcano: Is one that is erupting or will soon erupt. Dormant volcano: Is one that has not erupted for a long time. Extinct volcano: Is one that has not erupted for more that 10000 years.

Are in many places in the world in many different shapes and sizes. Types of volcanoes: •

Fissure volcano

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Shield volcano

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Dome volcano

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Ash cinder volcano

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Composite volcano

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Caldera volcano

Volcanoes produce lava and rocks we find in the Earth’s surface. Magma forms igneous rocks. These fragments are called thepra. Types of thepra: •Dust •Bomb •Ash •Lapilli Liquid lava flows fast and forms smooth folds that look like rope. This is called pahoehoe. When slow, sticky lava gets hard, it forms rocks with sharp edges. This is called aa. Sometimes lava forms long, thin strings like human hair. It’s called pele’s hair

The floor of the ocean is similar to dry land. There are flat plains, mountain ridges, canyons and trenches in the ocean floor. There are more volcanoes under the ocean than on land

The minerals and chemicals in the lava and ash make the soil fertile so it is good for farming. Volcanoes also help to produce electricity. They heat rocks that are near the Earth’s crust. When these rocks heat underwater, it turns to steam. People use this steam to make electricity. This called geothermal energy.

Specials scientists are called volcanologists. They study volcanoes in different ways. They study rocks and ash from long ago. These helps to learn about the volcanoes’ history and to know what is going to do. Because of this, people who live near volcanoes can plan what to do. Volcanologists wear Special Suits with they colled lava.