1. Where does magma come from? The mantle!

2. Solid mantle rock can melt to form magma in either of these cases: 1.Decrease in pressure – Occurs at hotspots and spreading centers 2.Addition of water – Occurs at subduction zones

3. Anatomy of a Volcano

4. Intrusion vs. Extrusion Intrusion – Magma – Molten rock can cool beneath the surface of the Earth Extrusion – Lava – Volcanic eruption

5. Active volcano

6. Extinct volcano

10. Key Points Solid mantle rock can melt to form magma by: – A decrease in pressure – Addition of water – An increase in temperature Intrusion – magma – Pluton – Batholith – Dike – Sill Extrusion – lava – Magma chamber – Conduit – Vent