danger‚ but it hasn’t erupted in a very long time. The last eruption was in 8051 BC. Mount Garibaldi began erupting about 250‚000 years ago and has grown steadily since then. Like most of the Cascade volcanoes‚ it has its own origins in the Cascadia subduction zone; a long convergent plate boundary that stretches from mid- Vancouver Island to Northern California. The first European to see the mountain in 1792‚ Captain George Vancouver‚ traded with the local natives in the area. When skiing became popular
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sediment. * The topmost layer‚ about 500 meters (1‚650 feet) thick‚ includes lavas made of basalt. Oceanic crust differs from continental crust in several ways: it is thinner‚ denser‚ younger‚ of different chemical composition‚ and formed above the subduction zones. Continental Lithosphere * The continental crust is 20 to 70 kilometers thick and composed mainly of lighter granite. The density of continental crust is about 2.7 grams per cubic centimeter. It is thinnest in areas like the Rift Valleys
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important to note that the majority of these deposits are found near or at mantle plumes or subduction zones associated with back-arc volcanos. These areas may no longer be near an active mantle plume or subduction zones‚ but instead can be used to locate the ancient position of one. Porphyry deposits are most often established in areas that are zones of low-angle subduction (Crooke and Hollings‚ 2005). Subduction
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CONTINENTAL DRIFT THEORY In the early 20th century‚ German scientist Alfred Wegener published a book explaining his theory that the continental landmasses‚ far from being immovable‚ were drifting across the Earth. He called this movement continental drift. Wegener noticed that the coasts of western Africa and eastern South America looked like the edges of interlocking pieces of a jigsaw puzzle. He was not the first to notice this‚ but he was the first to formally present evidence suggesting
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together. If an oceanic plate was involved subduction would occur. Subduction is when two plates converge and one goes under the other. Usually if there are two oceanic plates coming together the older/denser plate would get subducted. If there was a continental plate with an oceanic plate the oceanic plate would subduct‚ because it is denser‚ but it is a whole different story if they are both continental plates. Since they are both continental there is no subduction mainly‚ but there is a collision. They
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but the relatively small amount of carbon in the biosphere allows life to exist‚ and carbon in the oceans and atmosphere control important greenhouse gases that affect climate on the planet. Thompson and Turk text‚ Fig. 21.9 Volcanism and subduction processes are both part of the Carbon Cycle that links the deep Earth (lithosphere and asthenosphere) to the atmosphere‚ hydrosphere and biosphere at timescales operating over millions of years. What happens to carbon found in the near-surface
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this mountain has achieved this status. The three main focal points in this report revolve around tectonic plate subduction‚ uplift around the Denali fault‚ and the rock composition of the mountain. The combination of these three forces are integral reasons for why the mountain has been able to grow to its size and why it’s been able to maintain its height. To understand how subduction has affected Denali and the Alaska mountain range‚ you first need to understand how plate tectonics work. The theory
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is a caldera which is situated above a subduction zone where the Pacific Ocean plate is consumed beneath the South American continental crust. The volcano is composed of viscous rhyolitic lavas and pyroclastics and is typical of the magmas rising through the young fold mountains of the Andes. The eruption is said to have been triggered by a string of earthquakes that occurred on 30th April. Here is a diagram showing how Chaitén is located above a subduction zone formed where the Nazca and South American
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location‚ such as Hawaii where the plate boundary is underneath a hot spot‚ which causes the Hawaiian chain islands. It is where the magma in the mantle breaks through the lithosphere to form extrusive landforms. Shield volcanoes can be formed due to subduction and they tend to start of as a submarine volcano (under water) at either an oceanic/ oceanic convergence or a hotspot. At a hotspot‚ the limited magma plumes rise and go in a circular motion due to the convection currents‚ this eventually lead to
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volcanoes on both the land and sea of this same significant line. The landward side of the andesite line has explosive eruption as it is located at subduction zones while the seaward side is locate at oceanic ridges. The explosiveness of the eruption has to do with the flow of the magma and for the landward side the magma originated from the subduction zone. This zone has magma that are of high viscosity‚ they are granitic-andesitic and excrude at 700-9000c‚ have thick short flows that has slaggy
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