Dynamic Planet
Gopher Invitational 2017
DO NOT WRITE ON THIS EXAM. Please record your answers on your answer sheet.
Multiple Choice (30 points-1 point each)
1. About how many active volcanoes are there on earth?
A. 10,000B. 5,000C. 1,500D. 500
2. How many major tectonic plates are there?
A. 30B. 12C. 7D. 5
3. Who first hypothesized the formation of Gondwana?
A. Alfred WegenerB. Benjamin FranklinC. Eduard SuessD. Nicolas Steno
4. An aulocogen is a:
A. Failed arm of a triple junctionB. Subducted plate that falls into the mantle
C. Failed formation of a mantle plumeD. A displaced mountain chain
5. Who proposed convection currents as a mechanism for seafloor spreading?
A. Doc EwingB. Bruce HeezenC. Arthur HolmesD. Marie Tharp
6. Who first showed that the ocean floor was made of young basalt, not old granite as previously thought?
A. Doc EwingB. Bruce HeezenC. Arthur HolmesD. Marie Tharp
7. Who first hypothesized that there was a rift valley running down the Mid-Atlantic Ridge?
A. Doc EwingB. Bruce HeezenC. Arthur HolmesD. Marie Tharp
8. Who is generally considered to be the father of seafloor spreading as we know it today?
A. Doc EwingB. Bruce HeezenC. Harry HessD. Arthur Holmes
9. Which of the following is NOT a valid method of deriving absolute plate spreading rates?
A. Hot spotsB. GPSC. Hydrothermal ventsD. Magnetic reversals
10. The average thickness of oceanic crust is about:
A. 1 kmB. 7 kmC. 13 kmD. 35 km
11. The average thickness of continental crust is about:
A. 1 kmB. 7 kmC. 13 kmD. 35 km
12. Which of the following is NOT a type of gravity anomaly?
A. Free-airB. BouguerC. GeoidD. Both B and C
13. Which of the following is NOT an actual rift-valley?
A. Rhine ValleyB. Red SeaC. East African Rift ValleyD. Keystone Valley
14. Isostatic rebound occurs after:
A. Tensional forcesB. Compressional forcesC. Glacial advanceD. Glacial Retreat
15. Which of the following pyroclastic debris is the smallest?
A. AshB. BombC. CinderD. Lapilli
16. Which of the following would lower rock melting temperatures?
A. More mafic rockB. Increase water contentC. Increase pressureD. Larger crystals
17. Fractional crystallization segregation follows the:
A. Hess progressionB. Wilson cycle C. Cope seriesD. Bowen’s reaction series
18. The lava in subduction volcanoes is sourced from:
A. The subducted slabB. Melted rock above the slab
C. The deep mantleD. Hot spots
19. Mid-ocean ridges are offset by:
A. Hot spotsB. Mantle plumesC. Transform faultsD. Normal faults
20. The mean elevation of land on Earth is ______many meters above sea level?
A. 840B. 560C. 220D. 100
21. If all the land on the Earth was moved into the ocean, about how deep would the sea be?
A. 10 kmB. 7 kmC. 5 kmD. 3 km
22. The formation of the isthmus of Panama led to the:
A. South American ExtinctionB. Great American Interchange
C. American Diversification EventD. American Redistribution
23. Horst and graben topography is dominated by what kind of fault?
A. NormalB. ReverseC. ThrustD. Strike-slip
24. Which of the following form from trench roll-back?
A. Rift basinB. Intermontane basinC. Foreland basinD. Back arc basin
Questions 25-30 refer to the image below:
25. Where would a forearc basin form?
A. Location 1B. Location 2C. Location 3D. Location 4
26. A is pointing to which of the following?
A. SubductionzoneB. AulacogenC. RidgeD. Hot spot volcano
27. B is pointing to which of the following?
A. Ocean trenchB. Normal faultC. Transform faultD. Mid-ocean ridge
28. Which location would be most likely to produce andesitic lava?
A. Location 5B. Location 6C. Location 7D. Location 8
29. Where would a backarc basin form?
A. Location 1B. Location 2C. Between 2 and 6D. To the right of 6
30. Which volcano is the closest analogue to Location 6?
A. Mauna LoaB. Mount VesuviusC. YellowstoneD. A and C
True or False (15 points-1 point each)
31. The asthenosphere is a compositional layer of the earth.TrueFalse
32. Kauai is the oldest Hawaiian island.TrueFalse
33. The Juan de Fuca plate shares a transform boundary with the TrueFalse
North American plate.
34. Alfred Wegener proposed that North America and EuropeTrueFalse
were drifting apart at around 30 meters per year.
35. Two driving mechanisms for seafloor spreading are slab push andTrueFalse
ridge pull.
36. The Vine-Matthews-Morley hypothesis theorized symmetricTrueFalse
magnetic patterns around mid-ocean ridges.
37. The Earth’s average density is about 3.0 g/cm3.TrueFalse
38. The upper mantle is two times as dense as continental crust.TrueFalse
39. The mantle makes up about 67% of the Earth’s mass.TrueFalse
40. The Yellowstone Hotspot has not erupted since 640,000 years ago.TrueFalse
41. A thrust fault is a low-angled normal fault.TrueFalse
42. John Tuzo Wilson proposed the idea of a transform fault.TrueFalse
43. The Wiechert-Gutenberg Discontinuity is between the core andTrueFalse
mantle.
44. The Mohorovicic Discontinuity is closer to the Earth beneath TrueFalse
oceanic crust than beneath continental crust.
45. Magma from mid-ocean spreading centers often originatesTrueFalse
from decompression melting.
Matching (25 points)
Match each of the following natural hazards with their corresponding characteristics or description. Each will be used once. (1 point each)
46. Faulting and shaking A / A. Primary earthquake hazards47. Landslides D / B. Mass-wasting from freeze-thaw action
48. Liquefaction E / C. Fast-moving current of hot gas and tephra
49. Tsunami G / D. Can be mitigated by lowering groundwater level
50. Lahar F / E. Occurs when soils lose their shear strength
51. Pyroclastic flow C / F. Volcanic mudflow
52. Solifluction B / G. Can be predicted from drawback phenomenon
Match each of the following layers of the earth with its corresponding characteristics or description. Each will be used once. (1 point each)
53. Inner Core C / A. Composed of low-density silicate rocks54. Outer Core E / B. Takes up about 84% of the Earth’s volume
55. Mesosphere F / C. Approximately 94% iron
56. Asthenosphere D / D. Effectively the Low-Velocity Zone
57. Mantle B / E. Layer in which S waves cannot propagate
58. Lithosphere G / F. Upper boundary defined by 660 km velocity discontinuity
59. Crust A / G. Forms the tectonic plates
Match each of the following North American geologic events with the its correct place in chronological order (1st is the oldest event). Order them based on what time each event began. (1 point each)
60. Taconic orogeny C. 3rd Ordovician 440 mya / A. 1st61. Laramide orogeny H. 8th Cretaceous 80-40 mya / B. 2nd
62. Formation of Midcontinent Rift B. 2nd 1.1 bya / C. 3rd
63. Formation of Bering land bridge J. 10th 70,000 ya / D. 4th
64. Inundation of Bering land bridge K. 11th 11,000 ya / E. 5th
65. Formation of isthmus of Panama I. 9th Neogene 12-15 mya / F. 6th
66. Alleghenian orogeny E. 5th Carboniferous 325-260 mya / G. 7th
67. Formation of Canadian shield A. 1st Archean-Precambrian / H. 8th
68. Acadian orogeny D. 4th Silurian to Devonian 375-325 mya / I. 9th
69. Completion of Pangaea F. 6th Early Permian 300-272 mya / J. 10th
70. Beginning of Pangaea break-up G. 7th Early Jurassic 175 mya / K. 11th
Calculation (15 points)
71. Using the provided data, calculate the average rate of movement in centimeters per year of the Kanto plate over a hot spot in the last million years and compare it to the rate 5 million years ago. 1 mile=1,609 meters (10 points)
Island / Age (millions of years)Pallet Island / 0.0
Viridian Island / 1.0
Pewter Island / 3.6
Cerulean Island / 4.8
Vermillion Island / 5.4
Islands / Distance apart (miles)
Pallet Island to Viridian Island / 1.2
Viridian Island to Pewter Island / 36
Pewter Island to Cerulean Island / 67
Cerulean Island to Vermillion Island / 75
Work for 1 million years:
Grading: 2 points for correct set-up (distance divided by age, distance conversion), 2 points for correct islands (check distance and age difference), 1 point correct final answer
Work for 5 million years:
Grading: 2 points for correct set-up (distance divided by age, distance conversion), 2 points for correct islands (check distance and age difference), 1 point correct final answer
72. How do the rates compare to each other? (2 points)
The 1 million year plate movement rate is less than the 5 million year plate movement.
Graders: 2 points for the correct relation.
73. How do the rates compare to the average seafloor spreading rate? (3 points)
Seafloor spreading rates typically range between 1 and 10 cm per year. This makes the 1 million year plate movement rate slower than the typical seafloor spreading rate and the 5 million year plate movement rate faster than the average seafloor spreading rate.
Graders: 1 point for giving an average seafloor spreading rate within the above range. 1 point for recognizing the 1 million year rate as being lower than average and 1 point for recognizing the 5 million year rate as being higher than average.
Cross-Section (25 points)
74. Determine the relative sequence of the events in the diagram below. Write the letter of the rock unit or geologic structure in its proper place in the event sequence. Event #20 is the youngest event. Use the words “tilting”, “folding”, or “erosion” where appropriate in the proper order as their own separate events. (1 point each)
Event 20: ErosionEvent 10: D
Event 19:FEvent 9: M
Event 18: ErosionEvent 8: Erosion
Event 17: TiltingEvent 7: H
Event 16: BEvent 6: Tilting
Event 15: KEvent 5: C
Event 14: NEvent 4: L
Event 13: ErosionEvent 3: G
Event 12: AEvent 2: Erosion
Event 11: JEvent 1: E
75. What kind of fault is H? How can you tell? (3 points)
A normal fault--the hanging wall has moved down relative to the footwall.
Graders: 1 point for recognizing it as a normal fault, 2 points for saying the hanging wall has moved down relative to the footwall if recognized as normal fault (do not accept “the hanging wall is below the footwall” and no points if they don’t say normal fault).
76. In reference to your answer to 75, near which kind of tectonic boundary would you expect to find this type of fault? (2 points)
A divergent boundary.
Graders: 2 points for divergent boundary, and 2 points for convergent boundary if they said “reverse fault” for question 3.