Student #:
Provide the best answer for the following multiple choice questions. There are 45 regular test questions scaled to a total of 130 points. There are also five bonus questions that can only help your score. Circle the correct answer on your test paper and hand it in along with your scantron form. Underlined answers are the correct answers.
1. What kind of plate margin is represented by the San Andreas Fault?
a. divergent margin
b. convergent margin (ocean-continental collision)
c. convergent margin (ocean-ocean collision)
d. transform margin
e. collision margin (continent-continent)
2. Why do you think that there is very little evidence for the accretion of the planetesimals at the surface of the earth?
a. weathering
b. subduction of tectonic plates
c. the earth's atmosphere blocked all of the accreting planetesimals
d. answers a and b are both correct
e. all of the above are correct
3. What is the main source of heat driving convection cells in the asthenosphere today?
a. radioactive heating
b. compressional heating due to increasing gravity
c. kinetic energy due to impacting planetesimals
d. answers b and c are both correct
e. all of the above are correct
4. The melting temperature of _____ must be reached in order for the earth to become compositionally zone:
a. silicon
b. Fe-Mg silicate minerals
c. Fe
d. water
e. crustal rocks
5. Spreading ridges can never be subducted (True or False)
a. true
b. false
Questions 6 and 7. We know from seismic wave data that the outer core is liquid and the inner core is solid; yet the actual temperature of the outer core is lower than the inner core's actual temperature.
6. How can we best explain the fact that the inner and outer cores are composed of similar metallic iron and nickel yet the outer core is liquid?
a. the melting temperature curve for iron-nickel is less than the geothermal gradient temperature in the outer core.
b. the melting temperature curve for iron-nickel is greater than the geothermal gradient temprature in the outer core
c. the melting temperature curve for iron-nickel is the same as the geothermal gradient temperature in the outer core.
d. the outer core is solid and the inner core is solid
e. the actual temperature of the outer core is greater than the inner core's actual temperature.
7. What makes the asthenosphere unique relative to the lowermost lithosphere and the uppermost mesosphere (upper mantle)?
a. its composition is vastly different from the lowermost lithosphere and uppermost mesosphere.
b. the asthenosphere is not unique relative to the other two structural units.
c. the asthenosphere is at the pressure melting temperature for the upper mantle composition.
d. all of the above are correct
e. none of the above are correct
8. A shield volcano is formed of alternating layers of ________.
a. pyroclastic and debris flows
b. pyroclastic and obsidian flows
c. lava and debris flows
d. basaltic lava flows
e. pyroclastic and andesitic lava flows
9. What is the significance of the change in direction of the Hawaiian Island chain and the Emperor Seamount chain?
a. the tectonic plate on which both island chain sit changed directions
b. each island chain formed from two different hot spots.
c. a single hot spot moved beneath the tectonic plate
d. one chain of volcanoes formed from hot spot volcanism while the other is part of a mid-ocean spreading ridge
e. none of the above
10-13. Use the rock-composition diagram shown below to answer questions
10-13.
You would be shown this diagram during the exam
10. What is the coarse-grained igneous rock that would be composed of approximately 25% quartz, 20% sodium-rich plagioclase, 50% potassium feldspar, and 5% biotite and amphibole?
a. granite
b. dacite
c. rhyolite
d. andsite
e. granodiorite
11. What is the fine-grained igneous rock that would be composed of approximately 60% calcium-rich plagioclase, 30% pyroxene, and 10% of either amphibole or olivine?
a. basalt
b. dacite
c. gabbro
d. andsite
e. granodiorite
12. Which of the combination of minreral assemblages shown below would not naturally occur in igneous rocks?
a. quartz, biotite and potassium feldspar
b. amphibole, potassium feldspar, and quartz
c. quartz, pyroxene, olivine
d. calcium-rich plagioclase, pyroxene, and olivine
e. all of these would likely occur in igneous rocks
13. Why are andesitic rocks usually porphyritic?
a. some minerals naturally grow larger crystals compared to other minerals
b. the heat flow beneath the earth is variable causing two mineral sizes
c. two staged cooling history for andesitic magmas
d. all of the above
e. none of the above
14. Which tectonic margin would tend to have deeper focused earthquakes?
a. divergent
b. transform
c. convergent
d. hot spot
e. intra plate
15. The Andes Mountains formed at a ____________ tectonic margin.
a. divergent
b. convergent (ocean continent)
c. convergewnt (ocean-ocean)
d. collision (continent-continent)
e. transform
16. S-waves ___________ as they travel through the outer core.
a. are absorbed
b. decelerate
c. accelerate
d. change direction
e. rebound
17. When two ocean plates converge ___________.
a. the younger plate will be subducted
b. the older plate will be subducted
c. the plate closest to ocean water will be subducted
d. a collision mountain belt will form
e. none of the above are correct
18-20. Magma is being erupted along a divergent margin.
18. What type of magma is erupted on the surface?
a. rhyolite
b. obsidian
c. andesite
d. pumice
e. basalt
19. This type of margin can be found _____________?
a. only in ocean basins
b. only on continents
c. along the San Andreas Fault
d. in ocean basins and continents
e. none of the above
20. What causes the divergence?
a. upwelling due to convection in the asthenosphere
b. downwelling due to convection in the asthenosphere
c. upwelling due to convection in the lithosphere
d. downwelling due to convection in the lithosphere
e. subduction zones cause draw down of the crust
21. Magmas are divided into three compositional ranges based mainly on ___________ content.
a. mafic content
b. silica content
c. iron content
d. water content
e. gas content
22. Most igneous rocks are predominantly composed of ______________.
a. iron and magnesium
b. silicon and oxygen
c. water and CO2 gas
d. iron and nickel
e. none of the above are correct
23-25 Match the magma type with the appropriate tectonic setting where it most likely forms.
23. Basalt answer e
24. Granite answer c
25. Andesite answers b or d would be correct
a. transform margin b. ocean-ocean convergence
c. continent-continent collision d. ocean-continent convergence
e. mid-ocean hotspot
26. The aesthenosphere is composed of rock rich in:
a. quartz and olivine
b. pegmatite
c. peridotite (>90% olivine)
d. basalt
e. amphibole and pyroxene
27. A granitic magma formed by wet partial melting will tend to solidify and form an igneous rock underground because:
a. granitic magmas travel an unusually long distance from their source region relative to other magma types.
b. because they have a high silica content
c. the effectiveness of water in reducing the melting temperature is greatly reduced.
d. answers b and c are both correct
e. none of the above are correct
28. A partial melt of the asthenosphere will tend to rise toward the surface because __________.
a. because of centrifugel forces
b. earth's magnetic field
c. convection cells in the outer core
d. gravity
e. the melt is less dense than the surrounding rock
29-33. Answer the following questions based on the three pie diagrams
showing average compositions of the three principal kinds of magma.
Pie Charts would be shown
granitic pie chart
andesitic pie chart
basaltic pie chart
A B C
D. all of the above are correct
E. none of the above are correct
29. What type of lava or magma would Chart A represent?
a. basaltic
b. granitic
c. rhyolitic
d. andesitic
e. obsidian
30. Which of the above lavas or magmas would have the lowest viscosity?
Answer with the corresponding letter below charts. c
31. Which of the above lavas or magmas would tend to be erupted from volcanoes above oceanic hotspots.
Answer with the corresponding letter below charts. c
32. Which of the above lavas or magmas would you expect to have the highest quartz content.
Answer with the corresponding letter below charts. a
33. Which of above magmas would you expect to represent the composition of the Mesosphere (middle and lower mantle)?
Answer with the corresponding letter below charts. e
34. Diamond is harder than graphite because:
a. diamonds have covalent bonds between its constituent atoms while graphite has metallic bonds between its constituent atoms.
b. diamonds and graphite have the same bonds except diamonds are made of an element that is simply harder than graphite.
c. diamonds have covalent bonds between its constituent atoms while graphite has vanderwahl bonds.
d. diamond and graphite have the same hardness except graphite is in powdered form.
e. none of the above is correct
35. The silicate tetrahedron (SiO4)? has a net charge of ___________.
a. +4
b. -4
c. -3
d. +2
e. 0 (it is balanced)
36. How does the silicate tetrahedron achieve charge balance?
a. it will share electrons between oxygen atoms
b. it will form ionic bonds with available cations
c. it will form metallic bonds with available cations
d. all of the above are correct
e. none of the above are correct
37. The inert gases (i.e., helium, neon, argon) rarely bond with other atoms because _________.
a. they have no electron shell valencies
b. they only have neutron in their nucleus
c. the have no electron shells
d. these elements will bond under the right temperature conditions
e. none of the above.
38. The compositional zonation of the earth is best described as a ___________.
a. density gradient
b. silicate mineral gradient
c. liquid to solid phase gradient
d. Fe-Ni gradient
e. plantesimal gradient
39. Angular momentum is mathematically described as Velocity x Radius x Mass (v x r x m). What would happen to the rotational velocity of the sun if it condensed from a gas cloud that extended beyond the orbit of Pluto?
a. its rotational velocity would stay the same during condensation
b. its rotational velocity would speed up during condensation
c. its rotational velocity would slow down during condensation
d. its rotational velocity might increase or decrease depending on the initial rotational velocity of the dust cloud.
e. none of the above are correct
40. Why does the sun have less angular momentum than the planets yet it contains 99% of the solar system's mass?
a. friction is slowing down its rotation
b. the gravitational attraction of the planets is slowing down its rotation
c. it has always been the case since its original formation
d. the sun's magnetic field is applying a drag on its atomosphere
e. none of the above are correct.
41-45. Using the diagram and chemical formulas of Muscovite and Quartz
shown below, answer questions 41-45.
Diagram would be shown
Muscovite Mica: K2Al4(Si6Al2O20)(OH,F)2
Diagram would be shown
Quartz: SiO2
41. How many oxygen atoms are being shared between the silicate tetrahedra in muscovite sheets?
a. one
b. two
c. three
d. four
e. two and three
42. How many oxygen atoms are being shared between the silicate tetrahedra in quartz?
a. one
b. two
c. three
d. four
e. two and three
43. What is the significance of (OH) in the muscovite crystal structure?
a. it is due to alcohol being degassed from the primitive mantle
b. it is water likely formed in the primitive mantle
c. it is water likely incoprporated during the subduction process
d. it is water resulting from asteroid impacts
e. it is alcohol stashed during prohibition
44. If the pyroxene chains are formed from silicate tetrahedra of four oxygen atoms to every silicon atom, why is the formula shown as (SiO3)?
a. two of the oxygen atoms are shared with another silicon atom.
b. Aluminum replaces silicon in the center of the tetrahedra.
c. pyroxene is not formed from tetrahedral (adjective) chains.
d. there are only three oxygen atoms surrounding the tetrahedra in pyroxene.
e. none of the above
45. Why does muscovite develop cleavage planes?
a. this mineral does not cleave.
b. this mineral cleaves between the covalent bonds of shared oxygen atoms.
c. the mineral cleaves between ionic bonds separating sheet pairs
d. the mineral cleaves between covalent bonds separating sheet pairs
e. none of the above are correct
Bonus Questions (Your bonus questions will be based on class questions)
46. Which of the following formations does not represent a Tertiary arkosic sandstone unit that you observed or discussed on the Stevens-Blewitt Pass field trip?
a. Roslyn
b. Lookout Mountain
c. Chumstick
d. Swauk
e. all of the above are Tertiary arkosic sandstone units
47. Name the predominant rock type from the Ingallís Creek Metamorphic complex exposed in the county barrow pit near Leavenworth Wa.
a. migmatite
b. slate
c. biotite schist
d. marble
e. none of the above were exposed in the county barrow pit.
48. What mineral group represents our major sources of iron?
a. carbonates
b. silicates
c. sulfides
d. oxides
e. sulfates
49. Lead, mercury and zinc ores are smelted (refined) from which mineral group?
a. carbonates
b. silicates
c. sulfides
d. oxides
e. sulfates
50. Paleomagnetism cannot provide geologists with information ______.
a. about the latitudinal position of tectonic plates over geologic time
b. about magnetic polarity changes over geologic time
c. about the longitudinal position of tectonic plates over geologic time
d. about the relative positions of tectonic plates to one another over geologic time
e. all of the above information can be determined using paleomagnetic
signatures in rocks.