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Volcanoes

Formation of a volcano

1. Hot liquid rock called magma reaches the surface of the ground through a narrow vent in the earth's crust.

2. It erupts violently, blasting lava, ash and boiling mud into the air.

3. This material collects around a vent in a cone shape.

4. Repeated lava flows add to this cone-shaped mass of material.

5. Together the repeated ash and lava layers build up to form a cone-shaped mountain.

Positive effects of volcanoes

1. New land is created for farming and living space, e.g. Iceland.

2. Minerals are created by volcanic activity. Lava soils are rich in minerals. Good for growing crops.

3.Geysers(hot spring) can be formed and help heat glasshouses for production of food. E.g. Iceland.

4. Dormant or extinct volcanoes are major centres of tourism. e.g Vesuvius in Italy.

Negative effects of volcanoes

1. When snow-capped volcanoes erupt, large mud flows are created, which often cover villages and towns.

2. Gases from volcanoes may kill people who live nearby.

3. Ash and lava flows can destroy towns causing death.

4. Giant tidal waves are created by volcanoes at sea. When they reach land they can kill people especially in low-lying places such as deltas.

Types of volcano

Active

Erupting regularly, e.g. Mount Helens in California.

Dormant

Has not erupted in a long time. May erupt again.

Extinct

Has not erupted over thousands of years. Will most probably not erupt again.

Keywords

Magma

Geyser

Vent

ash

Crater

Pacific Ring of Fire

Largest earthquake and volcano zone is called the Pacific Ring of Fire. It lies around the edge of the Pacific Ocean.

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