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* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
VOLCANOES VOLCANOES • Up until now, we have discussed the earth and its construction. • We have discussed the ____________ and ____________ and _____________________. • In a way, our discussion of ________________ will extend that old knowledge. VOLCANOES • A __________________ is a weak spot in the crust where magma leaks to the surface. • When magma escapes to the surface, it’s called ______________. VOLCANOES • There are about ________________________ on land today. • We know there are many more beneath the sea, but because there are parts of the ocean floor which are inaccessible, it is difficult to __________ or even _____________ them. VOLCANOES • Volcanoes often occur in _______________. • One of the most well known volcanic belts is the _______________________around the rim of the _______________________. VOLCANOES VOLCANOES • You may have noticed that he volcanic belts occur near the ________________________ of the earth’s plates. • This is because when __________________ or __________________________ occurs cracks form in the crust which make it easy for volcanoes to occur. VOLCANOES • Underwater volcanoes spew magma constantly and ______________ form ______________ or underwater mountains. • This happens at __________________ plates. • There may be a time in the future where our map looks ______________ like it does today! VOLCANOES • When oceanic plates ___________________, volcanos can be created. • The plate that subducts gradually melts as it gets closer to the warm material of the _____________________. • Since _____________________ is less dense than the rock above it, it rises to the surface. • Hence, a ___________________ is formed. VOLCANOES • Since volcanos often occur in _____________, islands that spring from the ocean often do so, likewise, in ____________________. • These are called ______________________. • These arcs echo the shape of the ocean _________________. VOLCANOES VOLCANOES • This can occur when an _________________ plate subducts beneath a _______________________ plate. • This produced the _____________________ in South America and the ________________ ____________________ in the United States! VOLCANOES • Not all volcanoes form along a ridge. • Some volcanoes form at what we call _______ _____________. VOLCANOES • This happens when material from deep within the mantle ____________, then ___________ forming ____________________. • When this magma breaks through the crust, we call it an ________________ and another volcano is formed. VOLCANOES • _____________________ can form near a fault or in the center of a plate. • There is one very famous hot spot under _____________________________________. • What did that form? VOLCANOES • Volcanic ____________________ have been explained in many ways over the years. • In Hawaii, there are many myths about the goddess of volcanoes, ___________________. • When she is angry, volcanoes erupt. • __________________________is formed when lava sprays from the ground and hardens in thin strands. VOLCANOES • Deep beneath the surface under volcanoes there is always a pocket of _______________. • This pocket is called a ___________________ ________________________. • The magma moves upward through a _________________ or a long tube that runs from the chamber to the surface. VOLCANOES • ________________________ and _________ can leave a volcano through what’s called a ________________. • Often there is a ___________________ on top of a volcano, but it may have several more ____________________ along the sides. VOLCANOES • The area covered by lava as it pours from a vent is called a _________________________. • Oftentimes the central vent will have a bowlshaped crater around it. • This is called a___________________. VOLCANOES • You guys know that trick I do with the pop bottle? • That happens because under pressure, the _______________________in pop is very compacted. • When you open the pop and release the pressure, the carbon dioxide can _______________. • This is also why pop bubbles when you open it. VOLCANOES • This is what happens in a volcanic _________________ as well. • Magma is under enormous pressure and when that _________________is released, the gasses in it _______________and an eruption occurs. VOLCANOES • That pressure builds until the magma ____________ or ____________ out of the vent. • Once all the magma has escaped, the remaining __________________ escape. VOLCANOES • In a geologist’s eyes there are two types of eruptions…___________ or ________________. • ________________ eruptions occur if the magma is low in ________________. • This magma has low ________________ and flows easily. • Because of this gasses bubble out ______________. VOLCANOES • As you could imagine, when the magma is high in ___________________, oftentimes eruptions are explosive. • Because of its _____________________ the magma often plugs the pipe. • And the pressure builds…and builds until and explosion happens. VOLCANOES • Explosive eruptions can actually ___________ lava. • When it cools it can be as fine as __________ or as course as ____________________ on a playground. • When there is an explosive eruption, the mixture of hot gasses, ash, and cinders is called ___________________________. VOLCANOES • While they are very different, both types of eruptions cause significant damage. • Quiet eruptions spew lava constantly _______________________ to and _______________ a large are around the volcano. VOLCANOES • An explosive eruption causes clouds of _____________________________________ ________________________. • The _______________ alone can bury entire towns. VOLCANOES • A volcano’s activity can last from a _________________ to ______________ _______________. • Geologist work tirelessly to determine __________________ or _____________a volcano will erupt again. VOLCANOES • A volcano has _________________ of activity. • The first is _____________________. • These are volcanoes that ________ erupting or ________________ of erupting in the near future. VOLCANOES • The second type is _________________. • These volcanoes are ones that scientist expect to ______________________ in near future. VOLCANOES • The final type is ___________________. • This is one that is _______________ to ever erupt again. VOLCANOES • Geologists use what’s called a ___________________ to detect slight changes in elevation near a volcano. • This can let geologists know ___________ or _______a volcano will erupt again. VOLCANOES • As destructive as volcanoes can be, they can ____________________ some of the world’s most spectacular and awe-inspiring landforms. • ___________________in Japan is one of the most beautiful and perfectly formed mountains in the world. VOLCANOES • Volcanic eruptions can create landforms made of ________________, _____________ and _______________________________. • These landforms include… – ____________________________________ – ____________________________________ – ____________________________________ – ___________________________________ VOLCANOES • ________________________are formed when lava spews slowly and over time creates layers of solidified magma that create a gently sloping mountain. • The ______________________are an example of shield volcanoes. VOLCANOES • _________________________ are when the debris from volcanoes gathers and forms a pile through which magma is still released. VOLCANOES • ________________________ are when layers of solidified lava ________________with layers of ash. VOLCANOES • __________________are when exceptionally viscous lava spreads _____________ before solidifying. • This creates a wide area of hardened magma that more resembles a ____________ than a mountain. VOLCANOES • Sometimes, volcanic mountains collapse. • When this happens the resulting crater is called a _____________________. • It happens when the magma chamber is _______________________ and the hill falls in on itself. • The crater fills with _____________ very often. VOLCANOES • Even with all the danger, people choose to live near volcanoes. • The reason for this is because they choose to take advantage of the incredibly __________ ______________________. • Volcanic ash is rich in _________________, ____________________and many other substances excellent for farming. VOLCANOES • Many more landforms can be formed by __________________ as well. • The include… – ______________________________ – __________________ – __________________ – _________________________ – _________________________________ VOLCANOES • A _________________________ is when the water wears away the rock around a _______________ where magma has hardened inside. VOLCANOES • ________________ and _________________ are basically rock ridges formed from magma leaking from a ________________ crack in the crust. • Dikes form _____________________. • Sills form _____________________. VOLCANOES • A ___________________ is formed when a large body of magma cools within the crust. VOLCANOES • __________________________form when a batholith is pushed toward the surface by tectonic forces. VOLCANOES • ____________________________ and ______________are two other creations of ____________________. • ___________________are when groundwater is heated and slowly rises to the surface, collecting in a pool. • _________________are more violent, and shoot from the surface due to built up pressure. VOLCANOES • Some people use the pressure built up from the volcanic areas to produce _____________. • This is called _________________________ and it can be used to produce ____________ and _______________________.