Where does magma come from? The mantle!

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

Anatomy of a Volcano

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

Active volcano

Extinct volcano

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