Geology Ch 2 – Flashcards
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Which of the following properly describes Mount St. Helens and the other Cascade volcanoes?
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They are young, active volcanoes built on a continental margin above a sinking slab of oceanic lithosphere.
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What causes the volcanoes and deep valleys of East Africa?
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A continental rift along parts of the African continent beginning to slowly separate
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Which of the following statements applies to the asthenosphere, but not the lithosphere?
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A zone in the upper mantle that deforms by plastic flowage
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What type of region is the modern-day Red Sea?
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A rift zone that may eventually open into a major ocean if Arabia and Africa continue to seperate
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What is the temperature that magnetite loses its magnetization?
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800 degrees C
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Which one of the following is an important fundamental assumption underlying the plate tectonic theory?
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Earth's diameter has been essentially constant over time.
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Which of the following paleoclimatic evidence supports the idea of the late Paleozoic supercontinent in the Southern Hemisphere?
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Tillites (rocks formed by glaciers) in South Africa and South America
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What process is evident at oceanic trenches?
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Sinking of oceanic lithosphere into the mantle at a subduction zone
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What causes the linear patterns associated with paleomagnetism on either side of mid-oceanic ridges?
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Normal and reversed magnetized strips roughly parallel to the ridge
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Which of the following was never proposed as evidence supporting the existence of Pangaea?
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Islands along the Mid-Atlantic Ridge with rocks dating back from 542 million to 2500 million years ago
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What was the name of the fossil flora that grew on Pangaea during the late Paleozoic?
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Glossopteris
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What type of boundary occurs along the Aleutian Islands in the North Pacific?
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A convergent boundary on a volcanic arc above the northward-subducting Pacific plate
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What type of plate boundary is usually associated with pull-apart rift zones?
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A divergent plate boundry
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Which of the following is not evidence supporting the theory of plate tectonics?
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Shifting plates were caused by changes in the Moon's orbit.
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Which of the following is an example of an active continent-continent collision?
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The northward movement of India into Eurasia
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Why was Wegener's continental drift hypothesis rejected?
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Because Wegener could not identify a mechanism capable of moving continents
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A very long-lived magma source located deep in the mantle is called a(n) __________.
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Hot spot
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A transform plate boundary is characterized by __________.
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A deep, vertical fault along which two plates slide past one another in opposite directions
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Where in the ocean does oceanic lithosphere sink into the mantle?
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At subduction zones along convergent plate boundaries
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What evidence did the Deep Sea Drilling Project find about the dates of rocks in the ocean basins?
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The ocean basins are relatively young; most ocean basin rocks and sediments are Cretaceous or younger in age.
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Which two scientists proved that a symmetrical magnetic pattern existed in seafloor basalts and related those stripes to spreading at a mid-oceanic ridge?
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Vine and Matthews
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What is the typical rate of seafloor spreading in the Atlantic Ocean?
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2 centimeters per year
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Which scientist argued forcefully for continental drift in the early part of the 20th century?
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Alfred Wegner
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The former, late Paleozoic supercontinent is known as __________.
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Pangea
