1. Volcanoes

2. Bellringer Read pages 262-269

3. Click for Mr. Parr’s Song

4. Volcanoes—cone-shaped hills or mountains formed by magma. 1. When magma flows onto Earth’s surface through a vent, it is called lava. 2. Tephra—bits of rock or solidified lava dropped from the air after an explosive eruption. 3. Some volcanoes form where Earth’s plates collide. a. One plate sinks, or is forced underneath, the other. b. Part of the plate that is forced underneath melts, forming magma chambers.

6. 4. Avalanches of hot, glowing molten rock that flow on cushions of hot gases down a side of a volcano are called mudflows. 5. How forceful an eruption is depends on the composition of the magma. a. More silica makes magma thicker and flow slower. b. More iron and magnesium make magma flows more easily. c. Water vapor trapped in the magma becomes steam and builds pressure. 6. The type of lava and gas contained in the lava determine the type of volcano that forms.

7. Click for Mr. Parr’s Magma Song

8. Four types of volcanoes: Shield Volcano Cinder Cone Volcano Composition Volcano Fissure Eruptions

9. Four types of volcanoes: 1. Shield volcanoes—Basaltic lava, which flows easily a. Forms a broad volcano with gently sloping sides b. Largest type of volcano c. Form where Earth’s plates are moving apart and magma is forced upward between plates

10. 2. Cinder cone volcanoes—high gas content in the magma a. Explosive, but short, eruptions b. Form a small cone of volcanic material from tephra

11. 3. Composite volcanoes—made of alternating layers of lava and tephra a. Steep-sided mountains b. Form where Earth’s plates are colliding and being forced underneath each other, or subduction zones.

12. 4. Fissure eruptions-magma that is very fluid a. Oozes from cracks in Earth’s surface b. Magma flows freely across the land, as flood basalt. c. Most of Earth’s crust beneath the plateau is flood basalts.

13. Earthquake and Volcano Notes Using what you just read and your textbook complete your Earthquake and Volcano note- taking worksheet and you will review the answers in 15 minutes.