Geol 101: Physical Geology Summer 2007 EXAM 1

Transcription

1 Geol 101: Physical Geology Summer 2007 EXAM 1 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 7 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. Who is considered to be the father of modern geology? A. Plato B. Pliny the Elder C. James Ussher D. James Hutton E. Alfred Wegener 2. Most modern geologic study is based on the precept of the Principle of Uniformitarianism, which states: A. the present is the key to the past B. the past is the key to the future C. the past repeats itself D. the past s future is the same as the future s past E. nothing ever changes in geology 3. In glass, atoms are arranged in a: (A) regular framework (B) random orientation 4. A silicate mineral contains: (A) oxygen (B) sulfur 5. Mica sheets are held together by: (A) Van der Waal's bonds (B) ionic bonds 6. Manufactured diamonds are: (A) not minerals (B) minerals 7. Diamonds are 2-3 billion years old. This is known because what part of a diamond stone can be dated radiometrically? (A) the polish (B) the carbon atoms (C) the inclusions (D) all of the above (E) none of the above 8. Strictly speaking, amber is a/an: (A) mineral (B) organic material (C) both of these 1

2 9. A mineral that breaks into sheets has cleavage in how many directions? (A) none (B) one (C) two (D) three (E) four 10. Which of the following statements is FALSE regarding evidence to suggest that Africa and South America were once joined? A. the two continents fit together well along their true edges at an ocean depth of 900 m B. both continents contain fossils of the plant Glossopteris and the aquatic reptile Mesosaurus C. rocks that are about 550 million years old match up perfectly across the continents D. both continents show compatible evidence of a glacial period during the Carboniferous E. the Caledonides mountain range matches up across the two continents 11. Which of the following was NOT part of Gondwana? A. Eurasia B. Africa C. India D. Australia E. Antarctica 12. Paleomagnetism studies often consider the latitude at which a certain rock formed. Which of the following magnetic properties only changes as a function of latitude? A. magnetic polarity B. magnetic reversals C. magnetic inclination 13. In the modern age, compass needles point towards magnetic north. However, about 700,000 years ago, compass needles would have pointed south because it was during a period of: A. normal polarity B. positive polarity C. inverse polarity D. reverse polarity E. shoddy compass construction 14. Which of these statements about paleomagnetism as determined from a study of spreading ridges is FALSE? A. there is a clear paleomagnetic signal in rocks to either side of a spreading ridge B. rocks along spreading ridges all show normal polarity, no matter what their age C. the paleomagnetic pattern on one side of a ridge is a mirror image of that on the other side of the ridge D. there is evidence that Earth s magnetic poles reverse approximately every half-million years E. all the world s spreading ridges show evidence of paleomagnetic reversals in the adjacent ocean rocks 15. If you were to collect samples of basalt at the following locations on the sea floor of the North Atlantic ocean, which sample would be the oldest? A. along the spreading ridge B. where the spreading ridge is exposed above water in Iceland C. just east of the spreading ridge D. just west of the spreading ridge E. along the coast of Africa 2

3 16. The oldest ocean crust anywhere in the Earth s oceans is about years old. A B. 12 million C. 180 million D. 250 million E. 4.6 billion 17. A rift valley can be found in the following type of plate tectonic setting: 18. The Cascades mountain range in the western U.S.A. is found in the following type of plate tectonic setting: 19. The San Andreas fault is found in the following type of plate tectonic setting: 20. An island arc can be found in the following type of plate tectonic setting: 21. The Himalayas mountains are found in the following type of plate tectonic setting: 22. When a mantle plume rises from the outer core boundary to the Earth s surface, it results in a/an: A. hot spot B. island arc C. volcanic arc D. subduction zone E. suture zone 3

4 23. On average, the geothermal gradient inside the Earth is about: A C per kilometer B. 100 C per kilometer C. 50 C per kilometer D. 25 C per kilometer E. 10 C per kilometer 24. The inside of the earth is not completely molten (i.e. liquid) because: A. it never gets hot enough to melt rocks deep in the earth B. the melting temperature of rocks increases as pressure increases C. the earth would collapse in on itself if it had a liquid interior D. none of the above because the inside of the earth is completely molten 25. As a rock starts to melt, the minerals with the lowest melting temperature will start to melt first, forming magma. This melted portion can get squeezed away from the remaining solid rock through a process called: A. partial melting B. fractionation C. differentiation D. buoyancy E. crystallization 26. Newly formed magma starts to rise towards the Earth s surface because: A. it is sucked upwards by erupting volcanoes B. it is squeezed upwards by the force of tectonic plate collisions C. it is less dense than the rocks around it D. there is no gravity inside the earth 27. The type of magma that has the lowest silica content is: A. intermediate B. ultramafic C. mafic D. felsic E. all magma has the same silica content 28. The type of lava that flows the fastest has: A. a high temperature and a high silica content B. a high temperature and a low silica content C. a relatively low temperature and a high silica content D. a relatively low temperature and a low silica content E. all lava flows at the same speed, regardless of temperature or silica content 29. Which of the following terms has the same meaning as coarse-grained texture in igneous rocks? A. aphanitic B. phaneritic C. porphyritic D. pyroclastic E. pegmatitic 30. What type of rock typically shows a vesicular texture? A. basalt B. tuff C. pumice 4

5 31. Which of the following minerals is NOT found in Bowen s Reaction Series? A. plagioclase B. amphibole C. olivine D. calcite E. quartz 32. How many active volcanoes are there in the world? A. about a million B. around 10,000 C. around 1,500 D. around 800 E The type of volcanic hazard that involves a huge cloud of tephra rushing down the slopes of a volcano is a: A. lahar B. lava bomb C. pyroclastic flow D. gas cloud E. ash fall 34. The type of volcanic hazard that involves a mudflow made of volcanic ash is a: A. lahar B. lava bomb C. pyroclastic flow D. gas cloud E. ash fall 35. Which of the following is characteristic of nonexplosive eruptions? A. shield volcanoes B. high-viscosity lava C. felsic lava D. Plinian columns E. island arc volcanoes like Krakatau 36. What type of volcano is Mount St. Helens? A. stratovolcano B. shield volcano C. cinder cone D. lava dome E. tuff ring 37. The most active volcano in the Cascades is (1) but the largest known eruption that occurred about 6800 years ago 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 5

6 38. Which of the following sequence of events accurately describes the build-up to the eruption of Mount St. Helens exactly 27 years ago today, on May 18 th, 1980? A. steam and ash release bulge on mountain earthquake landslide lateral blast B. bulge on mountain steam and ash release earthquake landslide lateral blast C. bulge on mountain earthquake steam and ash release landslide lateral blast D. steam and ash release bulge on mountain landslide lateral blast earthquake E. bulge on mountain earthquake steam and ash release lateral blast landslide 39. Diagenesis can occur by: (A) recrystallization (B) frost wedging 40. Clastic sedimentary rock is formed out of: (A) chemical reactions (B) detritus 41. Sediment can be converted to sedimentary rock by: (A) diagenesis (B) metamorphism 42. The spires at Bryce Canyon National Monument are the result of: (A) differential weathering (B) volcanic extrusion 43. Lake sediments such as varves suggest a: (A) low energy depositional environment (B) high energy depositional environment 44. The removal of material from its source area is: (A) weathering (B) erosion 45. Technically, lunar soil is not "soil"; it is: (A) regolith (B) mineral (C) humus 46. Because they occur in a reducing environment, organic sediments such as coal are often associated with the iron sulfide mineral: (A) pyrite (B) hematite (C) limonite (D) magnetite (E) all of the above 47. Rock salt and gypsum are good examples of: (A) evaporites (B) clastics 48. The process by which slabs of rocks bounded by sheet joints slip off host rock is: (A) foliation (B) exfoliation 6

7 49. Yosemite National Park is famous for its domes, which were formed by: (A) exfoliation (B) volcanic action (C) ocean bottom processes 50. The opening of cracks by repeated freezing and thawing of water is: (A) mechanical weathering (B) chemical weathering BONUS QUESTIONS 51. What must always exist inside the crystal structure of a ferromagnesian silicate mineral? A. Ca and Na B. Si and Ca C. Fe and Mg D. Fe and K E. Mg and Na 52. The top of Mt. Everest exhibits (1) which indicates that (2). A. (1) a suture zone (2) it must be an ocean-continent plate boundary B. (1) a crater (2) it must be a volcano C. (1) constant elevation (2) the collision between India and Asia is now complete D. (1) glacial features (2) it used to be near the south pole as part of Gondwana E. (1) sea shell fossils (2) it is made of old ocean floor that got uplifted during collision 53. The largest type of pluton is called a: A. dike B. volcanic pipe C. laccolith D. sill E. batholith 54. The world s largest lava dome is: A. Mount St. Helens B. Mauna Loa C. Mount Hood D. Lassen Peak E. Crater Lake 55. The last Cascades volcano to erupt before Mount St. Helens in 1980 was: A. also Mount St. Helens B. Mount Rainier C. Mount Hood D. Lassen Peak E. Mount Shasta 7