1. Volcanoes & Volcanic Activity By Philipp S., 3 rd hour

2. Shield Volcano They are a large volcano which has shallow-sloping sides They are a large volcano which has shallow-sloping sides They have basaltic magma that is not viscous -> so it flows very far They have basaltic magma that is not viscous -> so it flows very far Shield volcanoes are not explosive because of the basaltic magma Shield volcanoes are not explosive because of the basaltic magmahttp://en.wikipedia.org/wiki/Shield_volcano http://www.alohablooms.com/img/snow012302/maunak ea_snow_coconut_leaf.jpg

3. Stratovolcano Is composed of many layers of hardened lava, tephra, and volcanic ash Is composed of many layers of hardened lava, tephra, and volcanic ash Is a tall, conical volcano Is a tall, conical volcano Has andesitic or rhyolitic magma which doesn’t flow good because it’s very viscous Has andesitic or rhyolitic magma which doesn’t flow good because it’s very viscous They are very explosive because of the non- viscous magma They are very explosive because of the non- viscous magmahttp://en.wikipedia.org/wiki/Stratovolcano http://en.wikipedia.org/wiki/Image:Popocat%C3%A9petl_ sunrise.jpg

4. Cinder Cone Made from rock fragments that accumulate around and downwind from volcanic vent Made from rock fragments that accumulate around and downwind from volcanic vent They are steep, conical hills They are steep, conical hills They are located on the flanks of shield volcanoes, stratovolcanoes and calderas They are located on the flanks of shield volcanoes, stratovolcanoes and calderashttp://en.wikipedia.org/wiki/Paricutin http://en.wikipedia.org/wiki/Image:Paricutin.jpg

5. Caldera Forms after a big eruption of a volcano Forms after a big eruption of a volcano The volcano collapses because there is no more magma under it. The volcano collapses because there is no more magma under it. They can explode in huge eruptions that are 2500 times as big as the eruption of Mt. St. Helens They can explode in huge eruptions that are 2500 times as big as the eruption of Mt. St. Helens http://en.wikipedia.org/wiki/Caldera http://en.wikipedia.org/wiki/Image:Santorini_Landsat.jpg

6. Lava Dome Forms in the crater of a volcano Forms in the crater of a volcano It is formed by a slow eruption of rhyolitic magma It is formed by a slow eruption of rhyolitic magma Most stratovolcanoes have a lava dome in their crater Most stratovolcanoes have a lava dome in their craterhttp://en.wikipedia.org/wiki/Lava_dome http://en.wikipedia.org/wiki/Image:MSH06_aerial_crater _from_north_high_angle_09-12-06.jpg

7. Flood Basalt They are results of gigantic volcano eruptions They are results of gigantic volcano eruptions Have lava with low viscosity -> basaltic Have lava with low viscosity -> basaltic They can be from 200,000km 2 to 1,500,000km 2 They can be from 200,000km 2 to 1,500,000km 2 http://en.wikipedia.org/wiki/Flood_basalt#Struct ures http://en.wikipedia.org/wiki/Image:3-Devils-grade- Moses-Coulee-Cattle-Feed-Lot-PB110016.JPG

8. Basaltic Lava High temperature: 1200°C High temperature: 1200°C Silica-poor, low viscosity (flow very good), low gas content Silica-poor, low viscosity (flow very good), low gas content The thin lava flows form shields The thin lava flows form shields ->Shieldvolcano ->Shieldvolcano Is not explosive, it’s flowing Is not explosive, it’s flowing http://www.teara.govt.nz/EarthSeaAndSky/Natur alHazardsAndDisasters/Volcanoes/1/ENZ- Resources/Standard/3/en http://www.earlham.edu/~yeakech/pics/basalt.jpg

9. Andesitic Magma Moderate temperature: 1000°C Moderate temperature: 1000°C Moderate silica content, moderate viscosity, moderate gas content Moderate silica content, moderate viscosity, moderate gas content It’s flowing and moderate explosive It’s flowing and moderate explosive Forms thick lava flows Forms thick lava flows Mainly in Stratovolcanoes Mainly in Stratovolcanoes http://www.teara.govt.nz/EarthSeaAndSky/Natur alHazardsAndDisasters/Volcanoes/1/ENZ- Resources/Standard/3/en http://www.ufrsd.net/staffwww/stefanl/Geology/volcano/p ahoehoe.jpg

10. Rhyolitic Magma Low temperature: 850°C Low temperature: 850°C Silica-rich, very high viscosity (doesn’t flow very good), high gas content ->very explosive Silica-rich, very high viscosity (doesn’t flow very good), high gas content ->very explosive Eruption product: pyroclastic flows, ash fall Eruption product: pyroclastic flows, ash fall Mainly in calderas Mainly in calderas http://www.teara.govt.nz/EarthSeaAndSky/NaturalHazar dsAndDisasters/Volcanoes/1/ENZ- Resources/Standard/3/en http://www.discoverourearth.org/student/volcanoes/image s/st_helens_mosaic3.gif

11. Plinian Eruption Is characterized by large gas blast eruptions which are very loud Is characterized by large gas blast eruptions which are very loud Extends columns of smoke and ash high into the stratosphere Extends columns of smoke and ash high into the stratosphere The ash deposits over large areas The ash deposits over large areas Erutpions can last from one day to several months Erutpions can last from one day to several monthshttp://en.wikipedia.org/wiki/Plinian_eruption http://upload.wikimedia.org/wikipedia/commons/f/f4/Vesuvi us1822scrope.jpg

12. Strombolian Eruption Eject lava bombs to altitudes of tens to hundreds of meters Eject lava bombs to altitudes of tens to hundreds of meters Is a low level eruption but can last very long Is a low level eruption but can last very long The lava flows are more viscous The lava flows are more viscous -> andesitic -> andesitichttp://en.wikipedia.org/wiki/Strombolian_eruption http://upload.wikimedia.org/wikipedia/commons/9/93/Stro mboli_Eruption.jpg

13. Hawai’ian Eruption Low level eruption, with basaltic lava Low level eruption, with basaltic lava The lava flows flow very far because basaltic lava has low viscosity The lava flows flow very far because basaltic lava has low viscosityhttp://en.wikipedia.org/wiki/Hawaiian_eruption http://www.ldeo.columbia.edu/news/2005/images/eruption. jpg

14. Phreatic Eruption Occur when magma makes contact with ground water Occur when magma makes contact with ground water The water evaporates nearly instantaneous The water evaporates nearly instantaneous This causes a steam explosion This causes a steam explosion It typically include rock fragments It typically include rock fragmentshttp://en.wikipedia.org/wiki/Phreatic_eruption http://upload.wikimedia.org/wikipedia/commons/ 8/8a/Phreatic.jpg

15. Sill Is a intrusion that intruded between older layers of sedimentary rock Is a intrusion that intruded between older layers of sedimentary rock They can be from fractions of an inch to hundreds of feet thick and up to hundreds of miles long They can be from fractions of an inch to hundreds of feet thick and up to hundreds of miles longhttp://en.wikipedia.org/wiki/Sill_%28geology%29 http://z.about.com/d/geology/1/0/J/S/sill.jpg

16. Batholith Forms from cooled magma deep in the Earth’s crust Forms from cooled magma deep in the Earth’s crust When the surrounding rock erodes the batholith stays because it is made out of very hard rock When the surrounding rock erodes the batholith stays because it is made out of very hard rockhttp://en.wikipedia.org/wiki/Batholith http://whatonearth.olehnielsen.dk/img/batholith.jpg

17. Dike It’s an intrusion that cuts cross pre-existing or old bodies of rock It’s an intrusion that cuts cross pre-existing or old bodies of rock They sometimes appear as swarms They sometimes appear as swarms They are made from either basaltic, rhyolitic or granitic magma They are made from either basaltic, rhyolitic or granitic magma http://en.wikipedia.org/wiki/Dike_%28geology% 29 http://www.calvin.edu/academic/geology/pics/adirondacks/ dike.jpg

18. Stock Have a surface exposure of less than 40 square miles Have a surface exposure of less than 40 square miles Is like a small batholith Is like a small batholith Most stocks are probably the tops of hidden batholiths Most stocks are probably the tops of hidden batholiths http://en.wikipedia.org/wiki/Stocks_%28geology %29 http://www.geo.arizona.edu/tectonics/Ducea/projects/Huat ulco%20batholith2.jpg

19. Laccolith Is between two layers of sedimentary rock Is between two layers of sedimentary rock Looks like a dome or mushroom Looks like a dome or mushroom Are formed by viscous magma -> andesitic or granitic magma Are formed by viscous magma -> andesitic or granitic magma It cools slowly down and forms large crystals It cools slowly down and forms large crystalshttp://en.wikipedia.org/wiki/Laccolith http://mason.gmu.edu/~sharlan/adelmountainvolcanics_fil es/image014.jpg