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Volcanoes

Chapter 8. Volcanoes. How do volcanoes form?. When magma (melted rock) gets to Earth’s surface, it erupts and forms a volcano. Ring of Fire – the area that many volcanoes are located by the plate boundary in the pacific ocean. Where do volcanoes form?.

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Volcanoes

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  1. Chapter 8 Volcanoes

  2. How do volcanoes form? When magma (melted rock) gets to Earth’s surface, it erupts and forms a volcano. Ring of Fire – the area that many volcanoes are located by the plate boundary in the pacific ocean.

  3. Where do volcanoes form? Most volcanoes form at plate boundaries. Magma Plumes/Hot Spots Divergent Boundaries Convergent Boundaries summary summary summary picture picture picture

  4. Hot Spots A volcanically active area that is not near a tectonic plate boundary

  5. What causes magma to form? Magma needs 3 things: • Temperature- • Rock has to get really hot to melt • High temperature • Pressure- • Low pressure • This is found near the crust • Magma takes up more space than rock. • Fluid- • Rock that has fluids like water can melt more easily than dry rock

  6. Review 8.1 • Hot spot • Magma • Volcano • Divergent boundary • Convergent boundary • Subduction • Locations of volcanoes • How magma forms • How rock melts • Mid-ocean ridge

  7. What kind of volcanoes form at Divergent boundaries? • Mid Ocean Ridge • Mafic lava – thin, runny, dark • When lava erupts under the water it hardens quickly New land Sea floor spreading Oceanic crust Oceanic crust Old land Old land magma Rift zone – deep cracks that form as two plates separate.

  8. What kind of volcanoes form at convergent boundaries? • Lava • comes from melted crust and melted mantle • mafic (rich in magnesium and iron) (thin, dark, runny) • felisc (rich in silica and feldspar)(thick, sticky, light in color) Big explosion Pyroclastic material – rocks, gas, ashes, large chunks Pyroclastic flow • Can destroy everything in its path • 700 degrees C super HOT!!

  9. Vent – openings where lava is released. Lava tubes- long pipelike structures created when the flow will cool and solidify on top while the interior continues to travel. Magma chamber – the magma that feeds the eruption pools deep underground in this structure.

  10. Types of Lava • 1. Lava – magma that has reached earth’s surface. • Thin and runny, like water • Thick and stiff • Made of different material • 2. Mafic – magma that comes from the mantle • Lava that has a lot of iron and magnesium • Not much silica • Dark in color

  11. Shield volcano • Lava quietly flows from the vent. • mountain covers a large area. • sides are gently sloped. • Mountain is dome-shaped. • wide tall mountain. • mafic lava – runny and dark. • Erupts over and over for a long period of time. • continuous non explosive eruptions.

  12. Cinder cone volcano • cinders and rock particles are blown into the air. • Mountain is small. • Mountain has steep sides. • lava and ash come out of small vents and spray out in the air. Pieces of hard lava fall on the ground (cinders). • cinders and ash build up around the vent to form a small, steep volcano • Example: Paricutin, Mexico

  13. Composite volcano • violent eruptions sends up volcanic bombs, cinders and ash. • quiet volcanic flow follows the explosion. Alternating layers continue forming the mountain. • mountain is large. • Sides steep. • mountain is cone-shaped. • Erupts over and over for a long period of time. • also called strato volcano. • Example: Mt. Vesuvius, Italy.

  14. Review 8.2 • Lava • Rift zone • Mantle chamber • Pyroclasitc material • Mafic • Felsic • Shield volcano • Composite volcano

  15. Effects of volcanic eruptions Harmful • Volcanoes hurt/kill people • Destroys buildings and trees • Creates changes in the environment • Pyroclastic flows bury anything in its path. • Snow and rain can cause floods and mudflows (lahars). • Hard to breathe • Damages crops • Ashes can block sunlight and make the world cooler for several years. • Affect Earth’s climate for several years. • Ash and gases released in the air can cause temperatures to go down.

  16. Effects of volcanic eruptions Helpful (benefits) • Volcanic rocks break down soil • Volcanic Soil contains nutrients for plant growth. • Geothermal energy – people can pump hot water out of rocks to make electricity or to heat buildings. • Volcanic rocks –used for build buildings, cat litter, soap, cleaners, and polishes

  17. Review 8.3 • Lahar • Geothermal water • Volcanic soil • Global effect of volcanic eruption • Uses of volcanic rocks. • Geothermal energy. • Large volcanic eruptions can cause…

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