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Volcanoes. 8 th grade Earth Science. There are three types of volcanoes:. Shield Composite Cindercone. SHIELD VOLCANOES. Formed by layer after layer of lava. Usually have low silica content, and gases can escape easily. Has quiet eruptions. Extremely broad and flat in shape.

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8th grade Earth Science

there are three types of volcanoes
There are three types of volcanoes:
  • Shield
  • Composite
  • Cindercone
shield volcanoes
  • Formed by layer after layer of lava.
  • Usually have low silica content, and gases can escape easily.
  • Has quiet eruptions.
  • Extremely broad and flat in shape.
  • Found in Hawaii.
shield volcanoes1
  • Shield volcanoes have gently sloping sides that can stretch for miles.
  • These pictures are Mauna Loa, a volcano on the Big Island of Hawaii.
composite volcanoes
  • Can sometimes be called Stratovolcanoes.
  • Formed by alternating layers of lava flow and cinders or ash.
  • Has a high silica content and gases are usually trapped.
  • Has explosive eruptions.
  • Mount St. Helens and Mount Rainier in Washington.
composite volcanoes1
  • Mt. Mayon, Phillippines


  • Arenal, Costa Rica (below)
  • Mt. Rainier, Washington

(bottom, left)

mt st helens composite
Mt. St. Helens (COMPOSITE)
  • Virtual Tour of Mt. St. Helens
  • Harry Truman – the man who refused to leave “his” mountain.
cindercone volcanoes
  • Formed by layers of cinders and ash, not a lot of lava erupts from these volcanoes.
  • Very explosive when it erupts.
  • Has trapped gases.
  • The shape is nearly perfect on all sides…

almost like an orange road pylon.

psricutin mexico cindercone
Psricutin, Mexico (CINDERCONE)
  • This eruptions that created Paricutin began in 1943 and continued to 1952. Most of the explosive activity was during the first year of the eruption when the cone grew to 1,100 feet (336 m). The cone continued to grow for another 8 years but added only another 200 feet.
mt etna italy composite
Mt. Etna, Italy (COMPOSITE)
  • In mythology, Etna was identified as the location of the forge of Volcan, home of the Cyclopses, and where the giant Enceladus laid (eruptions being his breath and earthquakes being his motion). Etna’s beauty, frequent eruptions, and long record of eruptions makes it one of the world’s best know volcanoes.
devils tower ship rock
Devils Tower/Ship Rock
  • Both pictures are the remaining core of the volcanic neck of a once active volcano.
  • Located in Wyoming (left)
  • Ship Rock, San Juan County

New Mexico (below)

latest eruptions
Latest Eruptions
  • Mt. St. Helens has been periodically erupting for the 2 years. It is building its peak back up --- slowly but surely.
latest eruptions1
Latest Eruptions
  • Montserrat Volcano in the Caribbean. A large explosion and dome collapse occurred on March 3, 2004, causing a high eruption column and basal surge.
latest eruptions2
Latest Eruptions

Etna Volcano in Sicily

Late October, 2002

materials thrown out of a volcano
Materials thrown out of a volcano
  • Lava – molten rock that oozes out of volcanoes.
  • Tephra
    • Ash – smallest sized tephra
    • Cinders – small pieces of cooled lava up to the size of a basketball.
    • Bombs – any projectile bigger than a basketball.
ash the smallest size tephra
ASH – the smallest size tephra
  • Volcanic ash can cover areas like a snow storm
types of lava
Types of lava
  • Aa – Thick, chunky and difficult flow
  • Pahoehoe – Thin, watery, and easily flows