Geology Chapter 3, 4 Review

Geology Chapter 3, 4 Review - Geology Chapter 3 & 4...

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CHAPTER THREE 1) What was Wegener’s continental drift hypothesis? That all continents were at one point linked in a mega-continent called Pangea and drifted away. 2) How does the fit of the coastlines around the Atlantic support continental drift? The coastlines seem to fit together like a jigsaw puzzle and mountain belts of the Appalachians lie adjacent to similar-age mountain belts in Greenland, Great Britain, Scandinavia, and Africa 3) Explain the distribution of glaciers as they occurred during the Paleozoic. All late Paleozoic glaciated areas lie adjacent to each other on a map of Pangea. When Wegener plotted the orientation of glacial striations, they all pointed roughly outward from a location in Southeastern Africa. The distribution of glaciations at the end of the Paleozoic era could easily be explained if the continents had been united in Pangea. 4) How does the evidence of equatorial climatic belts support continental drift? The regions of North America, Southern Europe, and northwestern Africa would have straddled the equator and had subtropical climates. Wegener found that each continent had coal, reef deposits, salt deposits, and sand dunes – defining the climate belts of Pangea. 5) Why were geologists initially skeptical of Wegener’s theory? Wegener could not explain how or why the continents drifted. 6) Describe how the angle of inclination of the Earth’s magnetic field varies with latitude. How could paleomagnetic inclination be used to determine the ancient latitude of a continent? Magnetic inclination depends on latitude, . For example near the magnetic equator the field lines are parallel to Earth (i.e., 0 degrees of dip), whereas at the magnetic poles the inclination angle is much steeper (and 'inwards for one hemisphere and 'out' for the other hemisphere). Thus, knowing that the inclination is ~ 60o 'in' would put you along a line of~ latitude (not exactly, b/c the magnetic equator isn't exactly equal to the geographic equator) near Virginia or thereabouts. 7) How does basalt develop paleomagnetism? Can paleomagnetism develop in sedimentary rock? If so, how? Basalt forms when lava from a volcano cools and solidifies. When the hot lava first comes out, the thermal energy makes its atoms wobble and tumble chaotically. Each atom acts like a mini- dipole, but they all point in different directions. When this happens, the magnetic force exerted by one atom cancels out the force of another. As the temperature decreases, basalt rocks start to solidify. As the magnetite crystals form and cool, the dipoles became parallel with each and with
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Geology Chapter 3, 4 Review - Geology Chapter 3 & 4...

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