1. Volcanoes
Chapter 13

2. Volcano: a vent in the surface of Earth, through which magma and gases are expelled.
Volcanism: any activity that includes moving magma onto Earth’s surface.
Igneous rock: formed when molten rock crystallizes.
Definitions

3. Buoyancy & Heat: Magma Rises
Rock melts and rises.
The magma melts surrounding rock, so the volume keeps growing.
It pushes upwards.
Buoyancy & Heat: Magma Rises

4. Dome Mountains

5. Magma rises at convergent boundaries, where subducted crust melts.
Magma also rises at divergent boundaries and at hot spots where convection lifts heat.
Volcano formation

6. Volcanic Mountains Lava is molten rock on Earth’s surface.
Magma is molten rock below the surface.
Magma meets the surface at a volcano.
Volcanic Mountains

7. Volcano Types Shield: mafic (thin) lava flows out in liquid form.
Cinder cone: felsic (viscous) lava explodes.
Composite: alternates.
Volcano Types

8. Volcanic Mountains

9. Active: A volcano that will likely erupt again in the future.
Dormant: A "sleeping" volcano that may erupt again.
Extinct: A volcano that will never erupt again. No eruptions for 10,000 years.
550 Active Volcanoes

10. Yellowstone Supervolcano