1. Volcanoes Forms when magma reaches the Earths surface and erupts as lava or ash

2. Volcano Formation - Melting occurs in asthenosphere -Magma is lava underground -Magma is less dense than surrounding rock it rises to lithosphere and creates cracks in the solid rock -cracks are how magma reaches surface

3. Plate Boundaries Eruptions occur on plate boundaries that separate, collide, or are hot spots

4. Divergent Plate Boundaries -Plates pull apart -they occur under water - A major divergent boundary above water is the East African Rift Valley Convergent Plate Boundaries -Plates come together -Most volcanoes on Ring of fire -Subduction zones where on plate goes below another

5. Hot Spots -Balloon like plume -Usually NOT near plate boundaries -Stationary (non moving) -Creates island chains in the ocean (Hawaii)

6. Types of Volcanos Volcanoes are classified by their size, shape, and mineral type Composite Cone - form at convergent boundaries - explosive eruptions - large, steep shape 1000’s of meters wide - composed of ash and lava - pyroclastic flows- a fast-moving current of hot gas and rock

7. Shield Cone -fluid lava erupts, travels far - broad, wide, flat shape - gas poor -composed of lava -quiet eruption Cinder Cone -high temp - gas rich - mafic -explosive, ejects cinders -smaller 100’s meter range - short eruption cycles - composed of ash