1 GEOL1010 Hour Exam 2 18 Oct., 2010 1. Most earthquakes occur: a) at depths greater than 400 km b) at depths less than 100 km c) at passive continent margins d) in the central regions of plates (cratons) e) in the lower mantle. 2. The deepest earthquakes occur at a depth of about: a) 50km b) 100km c) 400km d) 670km e) 2900km. 3. Seismic waves that travel through the interior of the Earth and propagate by shear (movement perpendicular to propagation) are: a) P-waves b)body-waves c) tsunamis d) S-waves e)surface waves 4. The point on the Earth’s surface directly above the rupture that causes an earthquake is known as the: a) fracture zone b) Benioff zone c) subduction zone d) focus e) epicenter 5. The exact location of the epicenter of an earthquake can generally be determined from: a) the time difference between body and surface wave arrivals at three different stations b) The time difference between P- and S-wave arrival times at three stations to determine distance and then using triangulation. c) the exact time of the surface wave arrivals at three different locations d) the direction of first movement of the S-wave arrivals at three different stations. e) the magnitude of the P-waves at three different stations. 6. A high-grade metamorphosed limestone is a: a) amphibolite b) eclogite c) granite d) schist e) marble 7. Every mineral or mineral assemblage has a range of temperatures and pressures at which it is the most stable configuration of the elements present. With increasing temperature at constant pressure, such mineral assemblages typically become: a)cooler b) coarser c) finer-grained d) more dense e)less dense. 8. Extensive reverse faulting in an area is an indication of regional: a) tectonic compression b) tectonic extension c) metamorphism d) tectonic shear e) tectonic uplift. 9. The fault responsible for the Haitian earthquake of January, 2010 trends east-west across the southern coast of Haiti and Dominican Republic. At this fault, the northern block has moved to the west (left) and the southern block to the east (right) without much vertical movement. This is an example of a: a) dip-slip fault b) left-lateral strike slip fault c) right-lateral strike-slip fault d) thrust fault e) reverse fault. Questions 10-12 refer to the faults illustrated in the diagram below. 10. 11. 12.2 10. In this type of fault the upper block has moved up along a low-angle fault plane relative to the lower block. This type of fault is a: a) reverse fault b) thrust fault c) normal fault d) strike-slip fault e) nobody’s fault 11. In this type of fault the upper block has moved up relative to the lower block. This type of fault is a: a) reverse fault b) thrust fault c) normal fault d) strike-slip fault e) not my fault 12. In this type of fault the upper block has moved down relative to the lower block. This type of fault is a: a) reverse fault b) thrust fault c) normal fault d) strike-slip fault e) your fault 13. The angle measured from the horizontal, perpendicular to strike, to any tilted planar feature in the rock such as bedding, is the: a) inclination b) strike c) declination d) dip e) tilt. 14. The age of most metamorphic rocks in Colorado is: a) less than 550 million years b) more than 4 billion years c)between 1000 and 2000 million years d) about 6000 years e) less than 65 million years 15. The Hadean Eon includes the time of the accretion of the planet up to about 4000 million years ago and constitutes about what percentage of Earth history? a)5% b) 15% c) 25% d)50% e) 85% 16. Dinosaurs roamed the land surface from about 250 million to about 65 million years ago. This era is subdivided into the Triassic, Jurassic, and Cretaceous which together are known as the: a) Hadean b) Proterozoic c)Phanerozoic d)Mesozoic e)Pleistocene 17. Which of the following radioactive isotopes is formed in the atmosphere by cosmic ray bombardment? a) 14C b) 40K c) 87Rb d) 238U e) 235U 18. 40K has a half-life of 1.3 billion years and decays to 40Ar. Why can’t K/Ar dating be used to date sandstone? a ) 40K half life too short b) 40K half life too long c) No K in quartz or sandstone d) daughter 40Ar not retained by quartz or sandstone e) 40K can only be used to date organic K taken from the atmosphere by plants. 19. A conglomerate formation has been intruded by a basalt dike. The basalt was dated radiometrically at 78 million years. Based on this date, we can infer the conglomerate layer to be: a) more than 78 million years old b) 78 million years old c) less than 78 million years old d) nearly 7000 years old e) no inference is possible 20. If the amount of a radioactive isotope is 1/16 the amount originally present, how many half-lives have gone by? a) 2 b) 3 c) 4 d) 8 e) 16 21. A break in the sedimentary geologic record where the older rocks have been tilted and eroded prior to resumption of sedimentation is called an angular unconformity. Such a break implies: a) a nearby subduction zone b) major thrust faulting in the area. c) An asteroid impact in the area. d) a nearby volcanic eruption e) A gap in the sedimentary record of 100 million years or more. 22. Where in the solar system is the asteroid belt? a) Beyond Pluto in the outer solar system b) Between the orbits of Mars and Jupiter c) Between Earth and Mars d). Between Saturn and Uranus e) Inside the orbit of Mercury3 23. Select the prediction(s) inconsistent with the Nebular Hypothesis? a) All planets should orbit the Sun in the same direction. b) All planets should orbit the sun in a roughly common plane. c) Inner planets should be enriched in volatile elements compared to the outer planets. d) All the above are predictions inconsistent with nebular hypothesis. 24. The outer planets are: a) Earth, Mars, Jupiter, Saturn b) Mercury, Venus, Earth, Mars c)Pluto and Charon d) Jupiter, Saturn, Neptune, Uranus e) Venus, Earth, Mars, Jupiter 25. The stable interior part of the continent is known as the a) terrane b) shield c) craton d) plume e) orogeny 26. An episode of mountain building is known as a(n): a) allocthon b) horst c) graben d) craton e) orogeny. 27. A small slice of new continental crust added onto the margin of a continent is a(n): a) accreted terrane b) allocthon c) shield d) craton e) epeirogeny. 28. The Canadian Shield
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