1. Updated 4/16/2009Created by C. Ippolito April 2009 Slide 1 Volcano How and Where Formed Magma and Erupted Materials Volcanic Landforms

2. Updated 4/16/2009Created by C. Ippolito April 2009 Slide 2 Where Volcanoes Form Subduction Boundaries –Cascade Mtns –Mariana Islands Divergent Boundaries –Iceland Hot Spots –Hawaiian Islands

3. Updated 4/16/2009Created by C. Ippolito April 2009 Slide 3 Magma Types Basaltic Magma –rifts, ocean hot spots Kilauea Andesitic Magma –subduction boundaries Mount St. Helens Rhyolitic Magma –continental hot spots Yellowstone Caldera

4. Updated 4/16/2009Created by C. Ippolito April 2009 Slide 4 Lava Flows Basaltic Lava Flows –(low silica) very fluid, fast moving –pahoehoe flow – twisted ropes viscous, slow moving –aa flow – sharp edges/projections Underwater Lava Flows –cools more quickly pillow lava

5. Updated 4/16/2009Created by C. Ippolito April 2009 Slide 5 Materials From Eruption Gases –concentration varies can effect “eruption explosions” –composition varies carbon dioxide – odorless sulfur compound – pungent odor “burn” Pyroclastic Materials –gases and solid fragments released by a volcano

6. Updated 4/16/2009Created by C. Ippolito April 2009 Slide 6 Pyroclastic Materials pyroclastics –particles ejected by expanding gases in magma vary by size –ash –welded tuffwelded tuff –pumice –lapilli –blocks –bombs

7. Updated 4/16/2009Created by C. Ippolito April 2009 Slide 7 Volcanic Landforms Shield Volcano –lava builds up in layers –broad base, gentle slope Mauna Loa Cinder Cone Volcano –molten lava thrown from vent Capulin Composite Volcano –layers formed from eruptions Mount St. Helens Mount Shasta

8. Updated 4/16/2009Created by C. Ippolito April 2009 Slide 8 Volcanic Landforms (con’t) Caldera –Large crater shaped basin formed when top of volcano collapses Crater Lake –http://earthsci.org/education/teacher/basicgeol/igneous/igneo us.htmlhttp://earthsci.org/education/teacher/basicgeol/igneous/igneo us.html