1. The Life of a Volcano The Life of a Volcano

2. When lava first comes up through cracks in the earth, a volcano is started. HOW the lava comes out and cools decides what the volcano will look like.

3. When thin layers of lava from a quiet eruption cool and harden on top of each other, a wide, gently sloping shield volcano is formed.

4. Thick layers of cinders and ash from an explosive eruption pile up to make steep sloped cinder cone volcanoes.

5. Sometimes a volcano alternates between quiet and explosive eruptions, forming a tall mountain of layered ash and lava called a composite volcano.

6. When a volcano can still erupt, it is called live or active. Between eruptions, a volcano can be inactive or dormant for many years.

7. Sometimes a dormant volcano can have the magma blocked by the layers of rock above it. This can form a rounded dome mountain or volcanic bulge.

8. If all of the lava is exploded out of a volcano, the pipe and magma chamber can be left empty. The top of the volcano can collapse in and form a larger crater called a caldera which seals up the volcano, making it dormant.

9. If a volcanic island collapses into a caldera, a ring island or atoll can form!

10. How do you know if a volcano is dormant or actually completely dead? We call volcanoes extinct if they are unlikely to erupt again, but they can still erupt even 1000 years later! There is no way to be sure!

11. Many extinct volcanoes still show their activity, but in a different way. Magma trapped under an extinct volcano can heat surface water and cause hot springs or geysers.

12. Hot springs are pools of water heated by nearby magma. They can contain dissolved gases and chemicals from the magma.

13. Geysers occur when hot water gets trapped underground. When the pressure builds up, it erupts and fountains into the sky!