Week 1 video quetions

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University of Oregon *

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308

Subject

Geology

Date

Apr 3, 2024

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docx

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2

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1. What is the outermost layer of the Earth called? Do you take this for granted? Do you feel bad about that after watching the film? The outermost layer of the earth is called the “crust.” In the past we have taken the earth’s crust for granted, however, after more research, we appreciate the earth’s crust more. 2. How old is the earth, according to this film? Do you buy it? Yes, I believe that the earth is 4.5 Billion years old. No question here, but notice the flowing lava in the lava lake beginning about 4 minutes in. The interactions of this moving solidified rock crust on top of a churning lake of lava is a good model of Plate Tectonics, speeded up so we can watch processes like rifting and subduction on our own time scale. Note which way the different “plates” are moving relative to one another; identify the different boundary types. 3. Which is older, continental crust or oceanic crust? Continental Crust 4. Where does the energy to drive Plate Tectonics come from? The energy is derived from the interior of the earth as a result of other radioactive decay of the initial elements that were involved in the formation of the mass that became the earth. 5. How much extension has occurred in the Basin and Range? How is this relevant to Oregon and the Pacific Northwest? The basin and range have grown wider by 100%. This is relevant because it pushed Oregon and the Pacific Northwest. 6. What is a xenolith? Where do they come from, and how do they get to the surface? Rocks that don't belong to the lava that brought them to the surface. Lava pulls rocks from below the surface and uplifts them. 7. What is the underplating of the crust? Why do you think magma rising from the mantle is likely to pause at the Moho, the boundary between the mantle and the crust? Underplating the process of magma that’s generated in the mantle is added to the earth’s crust but at the base of the crust, eventually cooling and adding the crust. The magma stops at the Moho because the crust is a solid layer of rock rather than the plastic mantle layer it was moving through it has to heat up the crust enough to move through it. 8. Where does most of our knowledge of the deep interior of the Earth come from?
Note the magnetic survey data shown at minute 32:30. Contrast the simple striped pattern of the NE Pacific oceanic crust with the irregular blobs and generally chaotic arrangement on the continent. Most of our knowledge of the deep interior of the earth comes from studying earthquakes. 9. Erosion reveals granitic batholiths by stripping away the overlying crust. What kind of crustal rocks were removed from above batholiths? Granite was removed from above the batholiths. 10. Where do pillow lavas form? Pay close attention to this process, you can see pillow lavas throughout Oregon. Note carefully the process of exotic terrane accretion starting at minute 41:40. Pillow lavas form from molten lava poured into the ocean. Today pillow lavas commonly form in Hawaii. 11. How much of Oregon is formed of exotic accreted terranes? Everything west of the rocky mountains was formed of exotic accreted terranes. 12. What is the goal or eventual result of erosion? Flatness is the goal of erosion.
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