Introduction to Volcanoes!
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Transcript of Introduction to Volcanoes!
What is a volcano?• A volcano is an opening in the Earth’s surface• Most volcanoes are dormant – Not currently active
• Active volcanoes– Hawaii: Kilauea volcano– Iceland: “the land of fire and ice”
How is a volcano formed?• Inside the earth heat
and pressure causes rock to melt and turn to magma
• Magma is forced up to the surface of the Earth because it is less dense – flows out through an
opening called a vent • The lava cools quickly to
form layers
Where do volcanoes occur?• Directly related to the
movement of the Earth’s plates along plate boundaries
• Occur where tectonic plates are moving together or apart
• Or may be formed by a hot spot
• Plates moving apart: Mid-Atlantic ridge separates and forms long cracks
• Plates moving together: Nazca and South American plates are being forced under the Caribbean plates
Hot Spots• Hot spots: Ex. Hawaiian islands are
volcanic islands but are not found on the edge of the plates
• Some areas in the mantle are hotter than others• These hot spots melt rock and it is forced upwards
towards the crust • Volcanoes are formed in a line because the Pacific
plate is moving over the hot spot