Geol 101: Physical Geology Fall 2006 EXAM 2

Transcription

1 Geol 101: Physical Geology Fall 2006 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. The largest type of pluton is a: A. batholith B. dike C. sill D. laccolith E. volcanic pipe 2. The type of volcanic hazard that involves a mudflow made of ash is called a: A. lahar B. tsunami C. pyroclastic flow D. debris avalanche E. lava bomb 3. The type of volcanic hazard that resulted in the deaths of the inhabitants of Pompeii in 79 AD was a: A. lahar B. gas cloud C. pyroclastic flow D. debris avalanche E. lava flow 4. A 16 million-year-old analog to the 251-million-year-old Siberian Traps is the: A. eruption of Mount St. Helens B. Columbia River Flood Basalts C. Idaho batholith D. Sierra Nevada batholith (Yosemite) E. eruption of Mount Mazama 5. The largest volcano on Earth is also the tallest mountain on Earth (measured from base to top). The volcano is called (1) and it is a type of (2). A. (1) Mauna Loa (2) stratovolcano B. (1) Mauna Loa (2) shield volcano C. (1) Kilauea (2) stratovolcano D. (1) Kilauea (2) shield volcano E. (1) Mauna Loa (2) composite volcano 6. When Mount St. Helens (1980) and Mt. Pinatubo (1991) erupted, they both produced a high, vertical plume of ejected pyroclastic material called a: A. lateral blast B. pyroclastic flow C. tephra cloud D. lapilli eruption E. Plinian column 1

2 7. Volcanoes with steep slopes that form from the accumulation of viscous lava and pyroclastic flows are: A. shield volcanoes B. stratovolcanoes C. composite volcanoes D. either A or B above E. either B or C above 8. If a volcano erupts explosively and then collapses into the void left by the emptying of the magma chamber below the mountain, it produces a wide and deep circular hole called a: A. crater B. cinder cone C. lava dome D. caldera E. maar crater 9. The most active volcano in the Cascades is (1) but the largest known eruption that occurred here in pre-historic times was the eruption of (2). A. (1) Crater Lake (2) Mt. St. Helens B. (1) Mt. St. Helens (2) Lassen Peak C. (1) Mt. St. Helens (2) Mt. Mazama D. (1) Mt. Mazama (2) Mt. Tehama E. (1) Mt. Shasta (2) Mt. St. Helens 10. The cities of Seattle and Tacoma are at risk from lahars that could be produced during an eruption of: A. Mount St. Helens B. Mount Rainier C. Mount Hood D. Mount Shasta E. Lassen Peak 11. Which Cascades volcano is actually the world s largest lava dome that sits inside the caldera of the ancient volcano called Mount Tehama? A. Crater Lake B. Mount Shasta C. Lassen Peak D. Mount Hood E. Mount St. Helens 12. Which of the following definitions most accurately pertains to weathering? A. the physical or chemical breakdown of rock exposed to air, water, and organic matter B. the downslope movement of loose material under the influence of gravity C. the sole process by which regolith becomes soil D. the movement of sediment by surface processes involving wind, water, and ice E. none of these statements defines weathering 13. Which of the following forms of weathering does NOT involve a mechanical weathering process? A. oxidation B. frost wedging C. thermal effects D. unloading E. biological activity 2

3 14. Which of the following combinations of weathering process and resultant effect is the correct combination? A. frost wedging and spalling B. oxidation and exfoliation C. thermal effects and acid mine drainage D. crystal growth and spalling E. unloading and exfoliation 15. Minerals like halite and calcite are particularly prone to chemical weathering through the process of dissolution. As a result, the following type of rock is prone to this type of weathering: A. limestone B. rock salt C. marble D. all of the above E. none of the above 16. What mineral commonly breaks down into clay when it is chemically weathered? A. quartz B. muscovite C. feldspar D. olivine E. calcite 17. The correct order of soil horizons from the top down is: A. O E A C B B. O A E B C C. O C B A E D. A O E C B E. A B C D E 18. Sedimentary rocks are the most common type of rock at the Earth s surface, but they actually only comprise about of the Earth s crust altogether. A. 5% B. 10% C. 25% D. 50% E. 75% 19. In sedimentary rock types, the term clastic means the same thing as: A. chemical B. biochemical C. biogenic D. detrital E. lithic 20. Match the sedimentary rock type shale with the corresponding grain size below: A. clay B. silt C. sand D. pebble E. boulder 3

4 21. Match the sedimentary rock type arkose with the corresponding grain size below: A. clay B. silt C. sand D. pebble E. boulder 22. Match the sedimentary rock type conglomerate with the corresponding grain size below: A. clay B. silt C. sand D. pebble E. none of the above 23. Sediment particles in quartz sandstone that formed in a desert are typically: A. poorly sorted and angular B. poorly sorted and well rounded C. well sorted and angular D. well sorted and well rounded E. made of feldspar 24. The two possible forms of sediment production that allow limestone to form are: A. biochemical and biogenic B. biogenic and detrital C. bioclastic and detrital D. detrital and chemical E. biogenic and clastic 25. Which of the following correctly describes the process that occurs during lithification? A. partial melting B. diagenesis C. metamorphism D. migmatite development E. metasomatism 26. The type of sedimentary structure that describes a layer of sediment in which the grain size steadily decreases from the bottom to the top of the layer is called: A. bedding B. cross-bedding C. graded bedding D. stratification E. a bedding plane 27. The correct combination of ripple shape and potential environment in which the ripple developed is: A. symmetric / single direction wind flow B. symmetric / river channels C. asymmetric / ocean waves D. asymmetric / tidal flats E. asymmetric / river channels 4

5 28. An example of a trace fossil: A. leaf imprint B. fossilized shells C. fossilized bones D. dinosaur footprint E. fossilized seeds 29. The zone of metamorphism is above the zone of (1) but below the zone of (2). A. (1) diagenesis (2) partial melting B. (1) magma (2) migmatites C. (1) 150 C (2) 800 C D. (1) partial melting (2) diagenesis E. (1) molten magma (2) partial melting 30. Which of the following statements regarding lithostatic pressure is correct? A. it is caused by the weight of the overlying rocks B. it is equal in magnitude from all directions C. it causes rocks to decrease in volume but it does not change the rock shape D. all of the above E. none of the above 31. Which of the following statements about metamorphism is FALSE? A. metamorphic rocks form from existing sedimentary, igneous, or metamorphic rocks B. metamorphism involves melting of existing rocks to form new minerals C. during metamorphism, existing minerals are transformed into new minerals D. metamorphism is controlled by pressure, temperature, fluids, and time E. metamorphic means change of form 32. Which of the following metamorphic terms does not belong with the others? A. foliation B. schistosity C. gneissic texture D. hornfels E. slaty cleavage 33. In the lists of metamorphic rocks below, which one shows rocks in the correct order from lowest to highest metamorphic grade for an initially clay-rich rock? A. slate - phyllite - schist - gneiss B. slate - schist - phyllite - gneiss C. schist - phyllite - slate - gneiss D. gneiss - slate - phyllite - schist E. gneiss - schist - phyllite - slate 34. Metamorphism of limestone produces: A. granulite B. hornfels C. quartzite D. slate E. marble 5

6 35. What type of metamorphism results in the development of an aureole? A. dynamic B. shock C. regional D. contact E. burial 36. Which type of metamorphism is associated with the process of metasomatism? A. thermal B. hydrothermal C. regional D. burial E. dynamic 37. Which type of metamorphism would NOT be expected to produce predominantly mechanical deformation? A. regional B. impact C. burial D. dynamic E. all of the above are dominated by mechanical deformation 38. What is meant by the term chronological sequence? A. it is one of the principles of stratigraphy used to determine relative ages B. it refers to the absolute ages of rocks C. it is the geologic time scale that we use to characterize the ages of all rocks D. it is the amount of time that a radioactive substance takes to decay E. it is the order that things happened in geologic history 39. In stratigraphy, the principle of stratigraphic superposition states that: A. all sedimentary beds start off being horizontal B. all sedimentary beds are separated by bedding planes C. a sedimentary bed is younger than the bed above it and older than the bed below it D. a sedimentary bed is older than the bed above it and younger than the bed below it E. a sedimentary bed must be older than any feature that cuts through it or disrupts it 40. The type of unconformity across which the beds have different inclinations is called a/an: A. disconformity B. angular unconformity C. nonconformity D. conformity E. intrusive contact 41. If magma intrudes into existing rocks in the crust, the boundary between these so-called country rocks and the igneous rock that forms from the magma is called a/an: A. disconformity B. angular unconformity C. nonconformity D. unconformity E. intrusive contact 6

7 42. Some rocks contain fossils of species that only lived for a relatively short time in Earth history. These are called: A. index fossils B. fossil assemblages C. fossil successions D. trace fossils E. Vanilla Ice fossils 43. The time divisions in the Geologic Column that represent the longest lengths of time are called: A. eras B. epochs C. eons D. periods E. years 44. The Holocene is an example of a/an: A. era B. epoch C. eon D. period E. absolute age 45. Which of the following statements is true of alpha decay when referring to radioactivity? 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 46. The correct definition of half-life when referring to an unstable isotope is as follows: A. the amount of time needed to completely decay all parent isotopes into daughter isotopes B. half the amount of time needed to completely decay all parent isotopes into daughter isotopes C. the amount of time needed to completely decay all daughter isotopes into parent isotopes D. the amount of time needed to decay half of the daughter isotopes into parent isotopes E. the amount of time needed to decay half of the parent isotopes into daughter isotopes 47. Stress is the same as: A. force B. pressure C. strain D. force divided by area E. pressure divided by volume 48. 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 7

8 49. If a rock deforms by flowing or bending, the deformation is said to be: A. elastic B. plastic C. ductile D. either A or B above E. either B or C above 50. For rocks that are being deformed inside the crust, as the temperature increases: A. the rocks get more brittle B. the rocks get less brittle C. the rocks get less ductile D. the strain rate increases E. the pressure must start to decrease BONUS QUESTIONS 51. What volcanic hazard was responsible for the deaths of 1700 people at Lake Nyos, Cameroon, in 1986? A. pyroclastic flow B. lava flow C. lava bombs D. gas cloud E. ash fall 52. Which of the following sedimentary structures is common in sand dunes? A. cross-bedding B. trace fossils C. graded bedding D. mudcracks E. all of the above 53. Which of the following is NOT a marine depositional environment? A. alluvial fan B. delta C. continental shelf D. continental slope E. beach 54. Cambrian, Ordovician, Silurian, Devonian, Carboniferous (Camels Only Sit Down Carefully). What comes next? A. Triassic then Permian B. Tertiary then Quaternary C. Cretaceous then Tertiary D. Permian then Triassic E. Jurassic then Cretaceous 55. A sedimentary bed contains three fossils: A, B, and C. Fossil A formed from an animal that only existed in the Cambrian and Ordovician Periods. Fossil B only existed in the Ordovician Period. Fossil C existed for a very long time on Earth- from the Cambrian to the Triassic Period. Based on this fossil assemblage, the age of the rock is: A. Cambrian B. Ordovician C. Silurian D. sometime between the Cambrian and the Triassic is all that we can tell E. impossible to determine 8