Slides on how volcanoes are formed, the main features of a volcano, effects of a volcano

1. Volcanic Activity

2. • Volcanoes form when magma reaches the
Earth's surface, causing eruptions of lava and
ash. They occur at destructive and
constructive plate boundaries
• Magma – Molten Rock Underground
• Lava – molten rock on Land
Volcanic Activity

3. The Mid Atlantic Ridge
Under the Atlantic Ocean lies a long, narrow
chain of mountains called the Mid Atlantic Ridge.

4. Mid Atlantic Ridge was formed when plates
separated and lava came to the surface
and cooled and hardened.

5. Iceland

6. Mid Atlantic Ridge In Iceland

8. The Pacific Ring of Fire.
Most earthquakes
and volcanoes
occur along this
line.

10. Volcanoes – Good and Bad
Benefits Drawbacks

11. • A volcano is a cone-shaped mountain or hill, formed
by eruptions of lava and ash.
• When magma reaches the Earth's surface it is called
lava. When the lava cools, it forms rock.
• Volcanic eruptions can happen at destructive and
constructive boundaries, but not at conservative
boundaries.
• Some volcanoes happen underwater, along the sea
bed or ocean floor.
Volcanic eruptions

12. • Magma rises through cracks or weaknesses in the Earth's crust.
• Pressure builds up inside the Earth.
• When this pressure is released, magma explodes to the surface causing
a volcanic eruption.
• The lava from the eruption cools to form new crust.
• Over time, after several eruptions, the rock builds up and a volcano
forms.
•
How volcanoes form

14. A volcano has several important
features:
• The magma chamber is a collection of magma
inside the Earth, below the volcano.
• The main vent is the main outlet for the magma
to escape.
• Secondary vents are smaller outlets through
which magma escapes.
• The crater is created after an eruption blows the
top off the volcano.

17. One way to describe volcanoes is in terms of
activity:
• Some volcanoes are still active and erupt
frequently (Etna and Vesuvius Italy)
• Some volcanoes are dormant (sleeping).
(Cotopaxi, Peru)
• Some volcanoes are extinct (never likely to
erupt again). (Slemish, Co.Antrim)
Different types of Volcanoes.

19. 2012 Junior Cert