Geol 101: Physical Geology Summer 2007 EXAM 2

Transcription

1 Geol 101: Physical Geology Summer 2007 EXAM 2 Write your name out in full on the scantron form and fill in the corresponding ovals to spell out your name. Also fill in your student ID number in the space provided. Do not include the dash and do not leave any spaces. Make sure you have all 8 pages of the exam. There are 55 questions. For each question, select the correct answer and fill in your choice on the scantron form. You MUST use pencil on the scantron form! 1. Metamorphism differs from diagenesis only in temperature and pressure. Diagenesis occurs at temperature and pressure. A. very high B. high C. intermediate D. low E. all of the above 2. Regional metamorphism of the granulite-amphibolite facies occurs deep in the crust at margins. A. convergent B. divergent C. translational D. intracontinental E. none of the above 3. When a rock melts, it is no longer a rock, it becomes a magma, and when it cools, an igneous rock. The melting point of rock is partially controlled by the amount of water in the rock, which is why upper mantle rocks melt so easily near. A. translational faults B. mid-ocean ridges C. subduction zones D. arctic islands E. all of the above 4. Differential stress has a direction of maximum stress which tends to flatten minerals such as on planes of foliation. A. quartz B. feldspar C. mica D. calcite E. none of the above 5. Slaty cleavage is along planes perpendicular to: A. the original bedding B. the normal to the original bedding C. the maximum stress direction D. the minimum stress direction E. both A and C 6. Quartz and form the light colored bands in gneiss. A. biotite B. amphiboles C. pyroxenes D. feldspar E. all of the above 1

2 7. When limestone is metamorphosed into marble, no foliation occurs but the crystals increase in size. A. quartz B. biotite C. calcite D. amphibole E. pyroxene 8. Dynamic metamorphism is also called metamorphism. A. catatonic B. cataclastic C. catastrophic D. calamatic E. catablastic 9. Contact metamorphism occurs adjacent to igneous intrusions, commonly resulting in a metamorphic. A. aureole B. oreo C. extrusion D. subduction E. pediment 10. Which principle of stratigraphy states that any horizontal sedimentary bed is younger than the bed below it but older than the bed above it? A. principle of chronological sequences B. principle of cross-cutting relationships C. principle of original horizontality D. principle of stratigraphic superposition E. principle of biostratigraphy 11. If a tilted sedimentary bed is cut by a vertical intrusive dike (i.e., the dike is not tilted in any way), the sequence of events in this case must have been: A. the dike intruded, then the bed formed around it, then the bed got tilted by tectonic stresses B. the bed got intruded, then the dike got deposited, then the bed got tilted by tectonic stresses C. the region got tilted by tectonic stresses, then the bed got deposited, then the dike intruded D. the bed got deposited, then the dike intruded, then the region got tilted by tectonic stresses E. the bed got deposited, then the region got tilted by tectonic stresses, then the dike intruded 12. Which of the following is NOT a type of unconformity? A. bedding plane B. disconformity C. angular unconformity D. nonconformity E. all of the above are unconformities 13. The correct arrangement of the different types of geologic time divisions, from longest to shortest, is: A. epochs, periods, eras, eons B. periods, eons, epochs, eras C. eons, eras, periods, epochs D. eons, epochs, eras, periods E. eras, periods, epochs, eons 2

3 14. Which of the following lists shows the youngest time division in each of the four categories mentioned in question 13? A. Hadean, Paleozoic, Cambrian, Paleocene B. Phanerozoic, Cenozoic, Quaternary, Holocene C. Phanerozoic, Mesozoic, Tertiary, Holocene D. Hadean, Cenozoic, Jurassic, Pleistocene E. Precambrian, Paleozoic, Cambrian, Paleocene 15. Which of the following statements is true of beta decay: A. an atom releases a pair of protons and a pair of neutrons from the nucleus B. an atom releases a proton and a neutron from the nucleus C. an atom releases an electron from the nucleus causing a neutron to turn into a proton D. an atom absorbs an electron into the nucleus causing the atomic number to decrease by 1 E. an atom remains unchanged but gives off gamma rays and generates a lot of heat 16. Radioactive decay causes U-238 to ultimately break down into Pb-206. In this reaction: A. U-238 is a parent isotope and Pb-206 is a daughter isotope B. U-238 is a daughter isotope and Pb-206 is a parent isotope C. U-238 and Pb-206 are both daughter isotopes D. U-238 and Pb-206 are both parent isotopes E. U-238 is a parent isotope and Pb-206 is a second cousin, twice removed 17. If the half-life of a radioactive isotope is 1 million years and a crystal forms containing 100 of these isotopes, how old is the crystal at the point in time when only 25 of the original radioactive isotopes are left in the crystal? A. 1 million years old B. 2 million years old C. 3 million years old D. 4 million years old E. 5 million years old 18. How old have moon rocks been determined to be, based on radiometric dating? A. 6 billion years old B. 4.5 billion years old C. 4 billion years old D. 3 billion years old E. 2.5 billion years old 19. It is safer to walk on thin ice with snow-shoes rather than with pointed high heels because: A. high heels impart a greater force on the ice B. snow-shoes impart a smaller force on the ice C. snow-shoes impart a smaller stress on the ice D. high heels impart a smaller strain on the ice E. snow-shoes impart an isotropic pressure on the ice 20. If a rock deforms under the influence of a stress, but then returns to its original shape when the stress is removed, then the deformation behavior is described as: A. brittle B. plastic C. elastic D. ductile E. magical 3

4 21. For rocks that are being deformed inside the crust, as the temperature increases: A. the rocks get more brittle B. the rocks get more ductile C. the rocks get more elastic D. the strain rate increases E. the pressure must start to decrease 22. Which of the following statements about joints is true? A. joints form as two sides of a fracture slide past each other B. joints typically open by several meters C. joints only form due to the cooling of lava or magma D. joints always form perpendicular to the direction of tensional stress E. joints are responsible for many earthquakes 23. The type of fault that forms in a region of the crust undergoing a combination of extension and lateral sliding: A. reverse fault B. normal fault C. oblique-slip fault D. left-lateral fault E. right-lateral fault 24. Along any inclined fault: A. the footwall moves up and the hanging wall moves down B. the hanging wall moves up and the footwall moves down C. the footwall moves to the left and the hanging wall moves to the right D. the footwall moves to the right and the hanging wall moves to the left E. the footwall is underneath the fault plane and the hanging wall is above it 25. If a fault has a dip of 90, then it is: A. horizontal B. vertical C. a normal fault D. a reverse fault E. a strike-slip fault 26. Which of the following is an example of a M7.3 normal fault related earthquake that happened in 1983? A. the great San Francisco earthquake B. the Good Friday earthquake in Alaska C. the Charleston, South Carolina earthquake D. the Borah Peak, Idaho earthquake E. the New Madrid earthquake 27. Along the San Andreas fault, the west side is moving towards the north and the east side is moving relatively towards the south. This makes the San Andreas fault: A. a normal fault B. a right-lateral fault C. a left-lateral fault D. a reverse fault E. either a left or right-lateral fault (depending on what side of the fault you are standing on) 4

5 28. What type of fold creates zig-zag patterns where the folded rocks are exposed at the surface? A. anticlines B. synclines C. monoclines D. any plunging fold E. all folds, regardless of type or orientation 29. On 26 th December 2004, a magnitude 9.1 earthquake caused a tsunami that killed about 283,000 people around the rim of the Indian Ocean. The earthquake itself occurred off the coast of this country: A. India B. Thailand C. Sri Lanka D. Indonesia E. Sumatra 30. A magnitude 9.0 earthquake hit the continental United States in the year 1700, also producing a tsunami. Where did this earthquake occur? A. along the San Andreas fault of California B. southern Alaska C. in the New Madrid region of Missouri D. near Hilo, Hawaii E. in the Pacific Northwest 31. Where do 80% of all earthquakes on Earth occur? A. along the tectonic plate boundaries B. in the continental interiors C. around the circum-pacific belt D. the mid-atlantic ridge E. Alaska 32. The largest earthquake in historic times had a magnitude of 9.5 and occurred off the coast of: A. Oregon B. Chile C. Mexico D. Alaska E. Indonesia 33. What type of instrument creates the picture to the right? A. an accelerometer B. a seismogram C. a seismograph D. a magnetometer E. a cardiograph 34. In the picture on the right, what is represented by the quantity labeled as A? A. the S-wave amplitude B. the P-wave amplitude C. the earthquake magnitude D. the seismic wave speed E. the P-S time interval 5

6 35. What is the typical depth of the epicenter of an earthquake? A. a few km B. up to 700 km C. the same depth as the focus D. zero (at the surface) E. any depth is possible 36. Which of the following types of waves is unable to pass through any liquid? A. P-waves B. sound waves C. water waves D. primary waves E. S-waves 37. The Modified Mercalli scale is used to measure: A. the Richter magnitude of an earthquake B. the moment magnitude of an earthquake C. the intensity of an earthquake D. the amount of energy released during an earthquake E. the height of the surface waves during an earthquake 38. Which of the following is an accurate definition of the term tsunami? A. it is a type of earthquake that occurs under the ocean B. it is a type of seismic wave that causes a lot of damage to tall buildings C. it is a water wave generated in the ocean as a result of an earthquake D. it is a type of landslide triggered in a mountainous region during an earthquake E. it is an ancient Japanese method of studying earthquakes 39. When seismic waves from an earthquake reach the boundary between the mantle and the liquid outer core: A. all of the body waves get refracted B. all of the body waves get reflected, but none are refracted C. all P-waves stop because they are unable to move through the outer core D. all S-waves vanish because they cannot move through a liquid E. all P-waves speed up as they pass into the outer core 40. As a result of seismic waves interacting with the liquid layer mentioned in the previous question, within what region do seismographs show no record of the earthquake ever having occurred? A. the S-wave shadow zone B. the P-wave shadow zone C. the epicenter D. the opposite side of the earth to the earthquake E. no such region exists 41. The boundary between the crust and the mantle is called the: A. Mojo B. Jomo C. Ohno D. Moho E. SloMo 6

7 42. The Earth has a magnetic field because: A. magnetic minerals are common at temperatures above the Curie point B. it has a magnetic iron-nickel core C. the liquid outer core creates an electric current which induces a magnetic field D. all planets have magnetic fields when they form E. it forms a magnetic resonance with planet Mercury 43. What occurs at a consistent water depth of about 135 m? A. the true edges of the continents B. the edge of the continental shelf C. the start of the continental rise D. the start of an ocean trench E. the limit of penetration by sunlight 44. Which of the following portions of the ocean floor is the flattest? A. ocean trenches B. mid-ocean ridges C. continental slope D. abyssal plains E. continental rise 45. The correct order of the 4 layers of rock types that make up oceanic crust, from top to bottom is: A. pillow basalts sediments gabbro sheeted dike complex B. pillow basalts sheeted dike complex gabbro sediments C. sediments pillow basalts sheeted dike complex gabbro D. sediments pillow basalts gabbro sheeted dike complex E. sheeted dike complex gabbro pillow basalts sediments 46. An example of a young, active mountain range that forms a part of the American Cordillera is: A. the Alps B. the Andes C. the Himalayas D. the Appalachians E. the Caledonides 47. The pile of sediments scraped off the top of an ocean plate where it begins to subduct is called: A. a trench B. a forearc C. an accretionary wedge D. a backarc E. a pluton 48. In which of these places would you expect to find a suture zone? A. Himalayas B. Sierra Nevada C. East African Rift Valley D. mid-ocean ridge E. Cascades 7

8 49. The Appalachians formed after the breakup and subsequent reassembling of the ancient supercontinent: A. Gondwana B. Pangea C. Rodinia D. Madagascar E. Nubia 50. When a microcontinent collides with a larger continent, it gets added to the edge of the continent and is then referred to as a/an: A. accreted continent B. terrane C. island arc D. accretionary wedge E. macrocontinent BONUS QUESTIONS 51. The end of the age of dinosaurs 66 million years ago also heralded the start of the: A. Cambrian B. Holocene C. Pliocene D. Hadean E. Tertiary 52. Cambrian, Ordovician, Silurian, Devonian, Carboniferous (Camels Only Sit Down Carefully). What comes next? A. Triassic B. Tertiary C. Quaternary D. Permian E. Jurassic 53. The Great San Francisco earthquake in 1906 was the most devastating earthquake in the history of the United States, killing about 3,000 people. This magnitude 7.8 earthquake happened because of motion along the: A. Cascadia subduction zone B. Aleutians subduction zone C. San Andreas fault D. Borah Peak fault E. Basin and Range faults 54. Which of the following statements is TRUE? A. an earthquake has only one magnitude but the intensity can vary B. an earthquake has only one intensity but the magnitude can vary C. the magnitude of an earthquake decreases with increasing distance from the epicenter D. the intensity of an earthquake is the least at the epicenter E. earthquake intensity is measured using the Richter scale 55. The tectonic plate that used to exist off the west coast of North America but which has long since been subducted, was the: A. Juan da Fuca plate B. Farallon plate C. Cocos plate D. Pacific plate E. Nazca plate 8