Volcanoes

Volcanoes

1. 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.

2. 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.

3. 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.

4. 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.

5. Keywords

   • Magma
   • Geyser
   • Vent
   • ash
   • Crater
   • Pacific Ring of Fire

6. 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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