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Volcanoes. What are the 3 major types of volcanoes?. Shield Gentle sloping sides, slow moving/runny lava Composite Tall, steep sides. Very violent eruptions. Thick sticky lava. Layers made of __________, _____, and pyroclastic materials Cinder Cone Short, ______ sides. Layers made of ash.
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What are the 3 major types of volcanoes? • Shield • Gentle sloping sides, slow moving/runny lava • Composite • Tall, steep sides. Very violent eruptions. Thick sticky lava. Layers made of __________, _____, and pyroclastic materials • Cinder Cone • Short, ______ sides. Layers made of ash. • What do you think pyroclastic means?
LAVA DOME A type of volcano often formed on or near another active volcano. Magma rises just under the crust and cools.
What is volcanism? Any activity that includes the movement of _________ toward or onto the ________ of the earth. Because of high temperature and pressure in the earth- pockets of magma form when surrounding rock ______, as more rock melts, the pocket grows Predict what happens next.
Why does the magma come to the surface? The magma is hotter, and less _______ than rock so it rises to the surface through _______ in the rocks- melting more rock. This occurs mostly at plate boundaries Any magma that makes it to the surface is called ______- the opening it comes through is called a ______. The build up of material over the vent is a _______. http://www.youtube.com/watch?v=mYekQtFLT2A http://www.youtube.com/watch?v=ZZnvzSpNLAE&feature=related What state do you think has the most volcanoes?
Volcanoes at subduction zones What happens here? Draw a picture of what you think happens.
Volcanoes at subduction zones O-C plate boundaries:Oceanic is pushed under the continental, melting the plate. Magma rises to the surface _________, the crust buckles _______, trenches form at the boundary. O-OSame as O-C, just under water. Volcanoes here are called island ______volcanoes. Japan and Alaska Why does Oceanic plate subduct more often the cont?
What happens at divergent boundaries? As plates move apart magma comes to the surface making mid ocean _________ Most of the eruptions here goes unnoticed, mountains and volcanoes are continuously forming. They can be seen only on land in ___________. Iceland is in part a __________. Where is Iceland?
Hot Spots Not all volcanoes are on __________. Sometimes magma can rise to the surface in the _____________ of a plate. These volcanoes seem like they are stationary, however, as the plate moves over the hotspot new volcanoes are formed, and old ones are __________ away. http://www.youtube.com/watch?v=tfXGbzgGJ74&feature=related
Types of lava Different types of ____________ make different types of lava. Mafic- oceanic crust- full of ________ and magnesium- dark in color- small __________- quiet eruptions Felsic- continental crust- ________rich- light in color- large crystals-violent eruptions Pahoehoe (Pah-Hoy-Hoy)- slow moving- “______” Aa (Ah Ah)- quick cooling- jagged chunks Pillow lava- when lava flows onto the ocean floor through ____________ Write 2 things you learned about volcanoes today.