and cause an earthquake‚ so safe is not a term that one can always associate with the absence of an active creep. 3) At one time it was thought that the deep-ocean trenches at subduction zones would be a good place for disposal of high-level radioactive waste. Why is this not a good idea? Explain what can happen at a subduction zone and what might occur if the waste were buried there. (Hint: see oceanic-continental convergence.) Over the years‚ different options have been considered as suitable permanent
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Jaesung Lee Geography 1 Professor Thomas Orf Chapter 14 Questions 1) The first evidence Wegner was able to find was the remarkable number of close affinities of geologic features on both sides of the Atlantic Ocean. He found the continental margins of the subequatorial portions of Africa and South America fit together with jigsaw-on-like precision. He also determined that the petrologic records on both sides of the Atlantic show many distributions- such as ancient coal deposits-that would
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Continental Crust: 2.7 g/cm cubed Oceanic Crust: 3.3 g/cm cubed Convergent Boundary: When the arrows are pointed towards the other direction‚ make sure to draw the subduction zone on your cross section towards the other direction as well. Convergent Boundary: When the arrows are pointed towards the other direction‚ make sure to draw the subduction zone on your cross section towards the other direction as well. What are the different types of plate boundaries? Convergent Boundary * ocean to
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Continental drift is the idea that the earth’s continents are drifting away‚ relative to each other across the ocean bed suggested by Alfred Wegner as part of his wider theory on plate tectonics. The plate tectonic theory suggested by Alfred Wegner in 1915 was that millions of years ago all the continents were joined together in one mass of land called ‘Pangaea’‚ the evidence for this was that coal was found on Antarctica‚ the shape of Africa and south America fit together and same fossils were
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direction was it moving before this change? * changed at 43 million years. * Before this change‚ it was moving north-northwest. [p. 29] 2. If the ocean floor is getting wider‚ why is the Earth not becoming larger? * old ocean floor sinks at subduction zones (trenches) [p. 14] 3. Distinguish between Earth’s crust and mantle. * Crust overlies mantle. It is basalt
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The Structure of the Earth and Plate Tectonics Structure of the Earth Mantle • The Earth is made up of 3 main layers: Outer core Inner core – Core – Mantle – Crust Crust The Crust • This is where we live! • The Earth’s crust is made of: Continental Crust Oceanic Crust - thick (10-70km) - buoyant (less dense than oceanic crust) - mostly old - thin (~7 km) - dense (sinks under continental crust) - young How do we know what the Earth is made of? • Geophysical surveys: seismic‚ gravity‚
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Evaluate how Plate Tectonic Theory helps our Understanding of the Distribution of Seismic and Volcanic Events (40 marks) The Plate Tectonic Theory developed in the late 1960’s‚ when people noticed how continents either side of the Atlantic Ocean seemed to almost fit together. Francis Bacon‚ an English Philosopher was aware of this as early as 1620. Topographical and geological evidence built up and allowed Alfred Wegener to publish a theory in 1912‚ suggesting that the continents were once all joined
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Internal processes which have been involved in the formation of boxwork weathered rocks. The major internal processes for my surface feature are: 1. The rock cycle and the formation of greywacke. 2. The uplift that brought the rocks from under the ocean up to the shore level. The rock cycle The rock cycle refers to the diverse set of natural processes that lead to the formation and transformation of igneous‚ sedimentary‚ and metamorphic rocks. The rock cycle shows that each type of rock can
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Boundary – Oceanic-Continental: When continental and oceanic plates collide the thinner and more dense oceanic plate is overridden by the thicker and less dense continental plate. The oceanic plate is forced down into the mantle in a process known as subduction. As the oceanic plate descends it is forced into higher temperature environments. At a depth of about 100 miles (160 km) materials in the subducting plate begin to approach their melting temperatures and a process of partial melting begins.
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Subducting A subduction zone is formed at convergent boundaries by which an oceanic plate slides slowly under a continental plate into the Earth’s mantle‚ as the result of pressure and friction. After a long period of time the overriding continental plate is lifted up creating a mountain range. This is how the Himalayas were formed. Sometimes the extreme heat and pressure exerted on the subducting oceanic plate causes an uplift of magma from the mantle which rises above the surface‚ creating a volcano
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