Chapter 7: Lesson 3

VOLCANOES

HOW DO VOLCANOES FORM?Pages D30 and D31

What is a Volcano?

• A place where molten rock, hot gases, and solid rock erupt

• It is an opening in the crust

• Vent: central opening in a volcanic area through which magma may escape

• Lava: magma that comes out of the vent–Erupted material cools and hardens

around the vent. This is a volcano!

• Crater: a cup-like hollow that forms at the top of a volcano and around the vent.

Volcano collapses and causes a larger crater

CALDERA

Volcanoes occur in belts, or long lines...

• Pacific Ring of Fire–Circles the Pacific Ocean

• Another is located around the Mediterranean Sea through Iran and continues through Indonesia to the Pacific

• 80% of land volcanoes are found on these two belts

• On the ocean floor, volcanoes line the mid-ocean ridges.

• Volcanoes form around boundaries

• Rift volcanoes: Form at divergent boundaries

• Hot Spot: a hot part of the mantle. Magma melts up through the crust. Middle of the plate is moving over a hot spots

Hawaiian Islands