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Volcanoes

Volcanoes. Liquid Hot Magma. Tungerahua Volcano, Ecuador Picture by Alcinoe Calahorrano. Definition of Volcano Mountain that forms when molten rock (magma) is forced to the Earth’s surface Number of active volcanos = ? 20 erupting right now (50-60/year) (160/decade)

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Volcanoes

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  1. Volcanoes Liquid Hot Magma. Tungerahua Volcano, Ecuador Picture by AlcinoeCalahorrano

  2. Definition of Volcano Mountain that forms when molten rock (magma) is forced to the Earth’s surface Number of active volcanos= ? 20 erupting right now(50-60/year) (160/decade) Number of volcanologists=1,500 Volcano Stats

  3. Non-explosive Eruptions Explosive Eruptions Volcanic Eruptions Lava flow Lava fountain What is Lava? -magma that flows onto the Earth’s surface

  4. What Erupts from a Volcano? Blocky lava Lava can be thick or thin. Pahoehoe Aa Pillow lava

  5. What Erupts from a Volcano? • Pyroclastic material • Rock fragments created by eruptions • magma explodes from volcano and solidifies in the air • existing rock is shattered by powerful eruptions EXPLOSIVE Lapilli Volcanic bombs Volcanic blocks Volcanic ash

  6. Types of Volcanoes Shield volcano Cinder cone volcano Composite volcano

  7. Types of volcanoes=Composite •  Composite volcanoes also known as stratovolcanoes make up some of the most know volcanoes that we have here on earth. A composite volcano is made up of many layers of harden lava and volcano ash of eruptions that have already taken place. That is usually why they can make such peaks that they have because of the constant overlapping that occurs. They really make beautiful mountains and draw people close to them and that usually isn’t good because when these volcanoes blow they are usually violent and have a higher number of casualties than other volcanoes.

  8. Types of volcanoes=Cinder cone • Cinder cones are a very classic look that a volcano can have. They have a bowl shaped crater at the top of the summit. The rock fragments, cinders are glassy and contain gas bubbles frozen into place as the magma explodes and is thrown into the air and is cooled quickly. So basically they are made up of ash and not lava. These volcanoes grow rapidly and made there maximum size fairly quickly. Cinders cones can become fairly large. Cinders are commonly found on the flanks of shield and stratovolcanoes.

  9. Types of volcanoes=Shield Volcano • Shield volcanoes are very large in size; the picture above shows an example of one which is the largest volcano on earth Mauna Lau. There are formed by lava flows of low-viscosity so over time and flow after flow is what makes the mountain grow. They can get so big that they have been confused with mountain ranges. Shield volcanoes are not only huge on earth but the largest mountain in our solar system Olympus Mons is a shield volcanoes. They are pretty common volcanoes.

  10. Craters, Calderas, and Lava Plateau • Crater • From explosions of material out of the vent and the collapse of material back into vent • Caldera • Much larger depression that forms when magma chamber empties and its roof collapses • Lava Plateau • Forms when lava erupts from long cracks, or fissures, and spreads out evenly (thousands of km)

  11. What causes volcanoes? • The Formation of Magma • Mantle rock melts when the temperature increases • or the pressure decreases.

  12. What causes volcanoes? • Where Volcanoes Form • Tectonic Plate Boundaries!!! ~75% world’s active volcanoes in Ring of Fire

  13. What causes volcanoes?

  14. What causes volcanoes? Hot Spots

  15. Types of Rock 2010Images from Geology.com unless otherwise noted

  16. What are Rocks? • A rock is a naturally occurring solid mixture of one or more minerals, or organic matter • Rocks are classified by how they are formed, their composition, and texture • Rocks change over time through the rock cycle

  17. Igneous Rocks • Igneous rock begins as magma. • Magma can form: • When rock is heated • When pressure is released • When rock changes composition • Magma freezes between 700 °C and 1,250 °C • Magma is a mixture of many minerals http://www.fi.edu/fellows/payton/rocks/create/igneous.htm

  18. Igneous Rocks • Felsic: light colored rocks that are rich in elements such as aluminum, potassium, silicon, and sodium • Mafic: dark colored rocks that are rich in calcium, iron, and magnesium, poor in silicon • Coarse-grained: takes longer to cool, giving mineral crystals more time to grow • Fine-grained: cools quickly with little to no crystals

  19. Igneous Rocks Coarse-Grained Fine-Grained Felsic Granite Rhyolite Mafic Gabbro Basalt

  20. Igneous Rocks • Intrusive Igneous Rocks: magma pushes into surrounding rock below the Earth’s surface • Extrusive Rocks: forms when magma erupts onto the Earth’s surface (lava), cools quickly with very small or no crystals formed http://www.windows.ucar.edu/tour/link=/earth/geology/ig_intrusive.html&edu=high&fr=t

  21. Obsidian What is Obsidian? Obsidian is a dark-colored volcanic glass that forms from the very rapid cooling of molten rock material. It cools so rapidly that crystals do not form. Igneous Rocks Obsidian is a dark-colored volcanic glass that forms from the very rapid cooling of molten rock material. It cools so rapidly that crystals do not form. Is this rock Felsic or Mafic? Is it fine-grained or coarse-grained? Is this rock Intrusive or Extrusive? Mafic, fine grained, extrusive

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