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Volcanism

Volcanism. Movement of magma inside the earth. Chapter 13 What are volcanoes. Lava- Magma that reaches the earths surface. Vent- The opening that lava flows through. Pyroclastic Material- Pyro; greek word for fire. Clastic; small particles or fragments.

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Volcanism

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  1. Volcanism Movement of magma inside the earth.

  2. Chapter 13 What are volcanoes Lava- Magma that reaches the earths surface. Vent- The opening that lava flows through. Pyroclastic Material- Pyro; greek word for fire. Clastic; small particles or fragments. These are the hot fire fragments that are ejected from a volcano. Volcano- opening in the earth’s crust where magma flows.

  3. Anatomy of a Volcano Volcanic activity begins in the upper mantle of the earth also known as the asthenosphere.

  4. Cross-section of a Volcano

  5. Parts of a volcano Crater- opening at the top of a volcano. Caldera- Large opening formed at the top of a volcano when the roof of a magma dome collapses. Crater Lake- lake formed in the crater of a volcano from melting snow or rain.

  6. Pyroclastic Materials Types of pyroclastic materials Dust- the smallest from of pyroclastic materials erupting from a volcano. Dust from a volcanic eruption can travel into the upper reaches of the earth’s atmosphere. Once it reaches the upper atmosphere, miles above the earth’s surface, atmospheric winds can move this dust around the globe. Ash- Sand size fragments ejected from a volcano. These fragments will normally be pushed up into the air in and around the volcanic source. Once in the air they will eventually fall back to earth. Cinders- Thumb nail size fragments that are ejected from a volcano. These hot fragments fly through very close to there source. As they fly through the air, they cool and release a small amount of gas causing tiny air holes. Bombs- Fist size, spindle shaped fragments. These can range in size from small to large depending on the explosiveness of the eruption.

  7. Volcanic Eruptions Volcanic eruptions can vary depending on the size of the volcano and the heating source or energy available.

  8. Volcanic Classifications Volcanic eruptions can be classified as quiet or explosive. Quiet eruption- lava flows freely through a vent or fissure. Explosive eruptions- pyroclastic materials and gases shoot into the air. Basic types of Volcanoes; Shield Volcano- Domed shaped volcano composed of layers of solid, hardened lava. • Wide base, with gentle dome shaped slopes. • Large crater or opening called a caldera.

  9. Volcanic Classifications Cinder Cone- Dust, ash and cinders are thrown out of the crater and settle to form the cone. • Steep sides - (34% angle of repose) • Narrow base (not very tall) • Explosive eruption

  10. Volcanic Classifications Composite Volcano (Strato)- Volcano made of alternating layers of pyroclastic dust, ash and hardened lava. • Quiet and explosive eruptions • Wide base (miles across) • Very Tall (Thousands of feet tall)

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