Download - Catalyst

ESS 101 Midterm Autumn 2005
Student #:
Name
VERSION A
Provide the best answer for the following multiple choice questions. There are 49 regular test questions and five
bonus questions. The bonus questions can only help your score. Circle the correct answer on your test paper and
hand it in along with your scantron form. Answers provided at the end of the exam.
1-3
1.
2.
3.
4.
a.
b.
c.
d.
e.
Match the magma type with the appropriate tectonic setting where it likely forms.
Iceland
a. basalt
Sierra Nevada batholith
b. granite
Phillipine Islands
c. andesite
d. peridotite
e. andalucite
The Columbia Plateau is composed of rock rich in:
granite
gabbro
peridotite (>90% olivine)
basalt
andesite
5.
a.
b.
c.
d.
e.
The melting temperature of granitic magma (wet melt) ______________:
increases as pressure is reduced (as it rises).
decreases as pressure is reduced (as it rises)
does not change as pressure changes
is not dependent upon the composition of the magma
none of the above answers are correct
6.
a.
b.
c.
d.
e.
A partial melt of the asthenosphere will not rise toward the surface because
_____________.
because of centrifugel forces
earth's magnetic field
convection cells in the outer core
the melt is less dense than the surrounding rock
the above question is incorrect because an asthenospheric melt will rise towards the surface
7. Aa basalts _______.
a.
are blocky textured flows that form as the viscosity increases during degassing
b.
are blocky textured flows that form as the viscosity decreases during degassing
c.
are ropey textured flows that form as the viscosity increases during degassing
d.
are ropey textured flows that form as the viscosity decreases during degassing
e.
none of the above answers are correct as “aa” is not a real word in geologic vocabulary
8. When two ocean plates converge ___________.
a.
the younger plate will be subducted
b.
the lighter plate will be subducted
c.
the older plate will be subducted
d.
a collision mountain belt will form
e.
none of the above answers are correct
9. The most widely accepted explanation for the earth's magnetic field is _______________.
a. movement of electrons in the molten iron of its outer core
b. movement of electrons in the molten iron of its inner core
c. small magnetic mineral present in its crust
d. the earth does not have a magnetic field
e. none of the above are correct
2
10.
a.
b.
c.
d.
e.
What kind of plate margin exists today in East Africa?
divergent margin
convergent margin (ocean-continental collision)
convergent margin (ocean-ocean collision)
transform margin
collision margin (continent-continent)
11. What type of volcanic rock would incorporate lithic fragments during the eruption.
a. andestite
b. volcanic tuff
c. granite
d. obsidian
e. pumice
12. Why does potassium feldpar develop cleavage planes yet it is a framework silicate mineral with all its oxygen
atoms shared between tetrahedra?
a.
this mineral does not cleave.
b.
this mineral has an aluminum atom in some of its tetrahedra which requires additional ionic bonds with
potassium atoms
c.
this mineral is not a silicate mineral and consists of weak ionic bond between
d.
the mineral cleaves between covalent bonds separating sheet pairs
e.
none of the above are correct
13. ______________ flows from Mount Vesuvius obliterated the Roman city of Pompeii in 79AD.
a.
Lava
b.
Pyroclastic
c.
Mud
d.
Lahar
e.
Glacier
14. Magnetic minerals that crystallize in a lava flow erupted near the North Pole today will ________.
a. be oriented perpendicular to the surface of the lava flow
b. be oriented parallel to the surface of the lava flow
c. be oriented at an oblique angle (not perpendicular or parallel) to the surface of the lava flow
d. all of the above answers are correct
e. none of the above answers are correct
15.
a.
b.
c.
d.
e.
Rank the chemical bonds forming minerals from weakest to strongest
ionic, Vanderwahl, covalent
Vanderwahl, covalent, ionic
covalent, Vanderwahl, ionic
ionic, covalent, Vanderwahl
Vanderwahl, ionic, covalent
16. What are the two most common elements comprising rocks of the crust and mantle.
a.
Iron (Fe) and Nickel (Ni)
b.
Iron (Fe) and Magnesium (Mg)
c.
Hydrogen (H) and Oxygen (O)
d.
Silicon (Si) and Oxygen (O)
e.
Oxygen (O) and Carbon (C)
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17.
a.
b.
c.
d.
e.
How does the silicate tetrahedron achieve charge balance?
it will share electrons between oxygen atoms
it will form ionic bonds with available cations
it will form Van der Waal bonds with available cations
all of the above are correct
only answers a and b are correct
18. Why do the large Jovian planets have molecular hydrogen in their atmospheres, but the smaller terrestrial
planest do not?
a. The Jovian planets are further from the sun and the hydrogen gas can condense and be held by gravity.
b. The terrestrial planets have a large component of molecular hydrogen in their interiors.
c. The Jovian planets do not have molecular hydrogen in their respective atmospheres.
d. all of the above answers are correct.
e. none of the above answers are correct
19. Most mined iron ore occurs in the ____________ mineral group.
a.
sulfide
b.
halide
c.
oxide
d.
carbonate
e.
silicate
20. Most metallic ore bodies, such as lead, silver and copper occur in the __________ mineral group.
a.
sulfide
b.
halide
c.
oxide
d.
carbonate
e.
silicate
21. What is the significance of (OH) in the amphibole 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 incorporated during the subduction process
d.
it is water resulting from asteroid impacts
e.
it is alcohol stashed during prohibition
22. Why does the topographic expression of the Hawaiian Island become progressively lower from the Big Island to
the island lying northwest?
a.
the topographic expression of all the Hawaiian Islands is the same
b.
the ocean lithosphere is less dense to the northwest and it floats higher
c.
there is a subduction zone to the northwest drawing the ocean crust downward
d.
the Big Island has a segment of continental crust within its interior
e.
the ocean lithosphere is lighter over the hotspot and it floats higher
23. Arrange the compositional zones of the earth according to their respective density (lightest to densest).
a.
continental crust, ocean crust, mantle, outer core, inner core
b.
ocean crust, continental crust, mantle, outer core, inner core
c.
inner core, outer core, mantle, continental crust, ocean crust
d.
outer core, mantle, ocean crust, continental crust, inner core
e.
inner core, outer core, mantle, ocean crust, continental crust
24. What kind of tectonic setting is represented by Yellowstone Park?
a.
divergent margin
b.
convergent margin (ocean-continental subduction)
c.
convergent margin (ocean-ocean subduction)
d.
hotspot
e.
collision margin (continent-continent)
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25. Meteorites that strike the earth are predominantly composed of ____________?
a.
iron-nickel and silicate minerals
b.
hydrogen sulfide and silicate minerals
c.
carbon-based materials and iron-nickel
d.
only material found in the earth’s core
e.
mainly materials found only in continental crust
26. Why do seismic waves decelerate in the “low velocity zone?”
a.
it is composed of low density liquid iron
b.
“the low velocity zone” is at the pressure melting temperature for the earth’s mantle
c.
seismic waves do not slow down in the “low velocity zone”
d.
the low velocity zone represents a part of the earth’s mantle that has a unique composition
e.
there is no “low velocity zone” below the surface of the earth
27. During differentiation of the earth into its compositional zones heat was generated from _________.
a.
kinetic energy of impacting planetesimals
b.
compressional heating during condensation
c.
radioactive heating
d.
all of the above are correct
e.
only answers a and b are correct
28. What mechanism have geologists proposed to explain the uplift of the Colorado Plateau and the rifting of
Nevada and Utah?
a.
a spreading ridge was subducted under California and is now upwelling beneath the Basin and Range
b.
a continental collison occurred 45 million years ago that caused the uplift of the Colorado Plateau
c.
a bolide impact occurred 27 million years ago that caused the rifting of Nevada and Utah
d
the Colorado Plateau has not been uplifted in recent geologic history, nor is Nevada and Utah rifting
e.
the causes of these two geologic events are unknown and no theories have been proposed
29. Transform plate boundaries are typically associated with ___________.
a.
convergent margins where the descending plates slows down during subduction
b.
convergent margins where the descending plates speeds up during subduction
c.
divergent margins where the rate of spreading is different along segments of the spreading ridge
d.
divergent margins where the rate of spreading is the same along segments of the spreading ridge
e.
none of the above answers are correct.
30. The cause of volcanism observed in the Cascades is similar to that of ________.
a.
Yellowstone Park
b.
the Phillipines
c.
the Columbia Plateau
d.
Himalaya Mountains
e.
the Hawaiian Islands
31. A shield volcano has a lower slope angle than a strato (composite) volcano because ________.
a.
its basaltic lava flows have higher viscosities than the andesitic flows of strato volcanoes
b.
its basaltic lava flows have lower viscosities than the andesitic flows of strato volcanoes
c.
the shield volcano is smaller than the strato volcano and cannot achieve the same slope angle
d.
it has more water content which lowers the melting temperature
e.
answers b and d are both correct
32. What is the significance of the change in direction of the Hawaiian Island and the Emperor Seamount chains?
a.
the tectonic plate on which both island chains sit changed directions
b.
each island chain formed from two different hot spots.
c.
a single hot spot moved beneath the tectonic plate
d.
the Hawaiian Islands formed over a hot spot volcanism while Emperor Seamounts are part of a mid-ocean
spreading ridge
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e.
none of the above answers are correct
33. Which tectonic margin would tend to have only shallow focused earthquakes?
a.
divergent
b.
transform
c.
convergent
d.
all of the above answers are correct
e.
only answers a and b are correct
34. Basaltic composition magma can form ____________.
a.
at sea floor spreading zones
b.
at continental rift zones
c.
above hotspots
d.
back arc spreading basins
e.
all of the above tectonic settings
35.
a.
b.
c.
d.
e.
P-waves ___________ as they travel through the outer core.
are absorbed
decelerate
accelerate
reverse
rebound
36. How can we best explain the fact that the inner and outer cores are both composed of metallic iron and nickel
yet the outer core is liquid and the inner core solid?
a.
the outer core is solid and the inner core is solid
b. the melting temperature for iron-nickel is greater than the geothermal gradient temperature in the outer core
c.
the melting temperature for iron-nickel is the same as the geothermal gradient emperature in the outer core.
d. the melting temperature for iron-nickel is lower than the geothermal gradient temperature in the outer core.
e.
the actual temperature of the outer core is greater than the inner core's actual temperature.
37. How can mantle rocks be brought to the surface of the earth, such as in the Cascades or Fidalgo Island?
a. they are brought to the surface along mantle plumes (hot spots)
b. they are brought to the surface in magma bodies related to subduction
c. they are “squeezed” to the surface along suture zones where collisions occur
d. all of the above answers are correct
e. none of the above answers are correct
38-40. Use the rock-composition diagram shown below to answer questions -.
Answer the following questions (-) based on the igneous rock classification chart shown below:
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38. An aphanitic (volcanic) rock composed of 5% quartz, 65% plagioclase, 25% amphibole and 5% pyroxene would
be classified as ________.
a. basalt
b. diorite
c. andesite
d. rhyolite
e. granite
39. An aphanitic (volcanic) rock composed of predominantly calcium-rich plagioclase and pyroxene would be
classified as __________.
a. basalt
b. diorite
c. gabbro
d. rhyolite
e. granite
40. Diorite may contains ________potassium feldspar.
a. 0%
b. 10-20%
c. 30-40%
d. 40-50%
e. 70-90%
41-43. Magma is being erupted from a divergent margin.
41. What type of magma is largely produced at this setting?
a.
rhyolite
b.
obsidian
c.
andesite
d.
pumice
e.
basalt
42. This type of tectonic setting can be found _____________?
a.
only beneath ocean basins
b.
only beneath continents
c.
along the San Andreas Fault
d.
beneath ocean basins and continents
e.
none of the above answers are correct
43.
a.
b.
c.
d.
e.
44.
a.
b.
c.
d.
e.
What is the main source of the erupted lava?
partial melt of the asthenosphere
partial melting of the subducting ocean crust and marine sediment
partial melting of the continental crust
mantle plumes
none of the above are correct
As magma crystallizes into igneous rock the residual melt __________.
will become more mafic (Fe-rich)
will be come more felsic (silica-rich)
will yield more explosive eruptions
answers a and c are both correct
answers b and c are both correct
45. What volcanic hazard is most commonly generated from eruptions of Mount Rainier?
a. pyroclastic flows
b. mudflows (lahars)
c. lava flows
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d. all of the above hazards are commonly associated with Mount Rainier eruptions
e. none of the above hazards are common for Mount Rainier because it is an extinct volcano
Lab Questions
46. In the geologic techniques lab each group completed a topographic cross-section of Icicle Creek and Wenatchee
River. What profile shape was indicative of a river valley?
a.
V-shaped
b.
Y-shaped
c.
U-shaped
d.
depends exclusively on the bedrock lithology
e.
none of the above answers are correct
47. In the plate tectonics lab we observed that oceanic crust comprising the Juan de Fuca plate was being created at
the spreading ridge at a rate ___________ the rate of its subduction beneath the North American plate?
a.
the same as
b.
less than
c.
more than
d.
not known compared to
e.
that is accelerating compared to
48. In the minerals lab the main diagnostic criteria for identifying the metallic mineral galena was _______.
a.
its high density
b.
its cubic cleavage
c.
its glassy appearance
d.
its gold color
e.
answers and a and b were both properties observed for galena
49. In the igneous rock lab we observed the rock andesite. It had a ___________ texture.
a.
coarse-grained
b.
fine-grained
c.
porphyritic
d.
glassy
e.
fragmental texture
Bonus Questions (There are five bonus questions #50-54)
Will be specific to a given lecture.
Answers:
1-a
2-b
3-c
4-d
5-a
6-e
7-a
8-c
9-a
10-a
11-b
12-b
13-b
14-a
15-e
16-d
17-e
18-a
19-c
20-a
21-c
22-e
24-d
25-a
26-b
27-d
28-a
29-c
30-b
31-b
32-a
33-e
34-e
35-b
36-d
37-c
38-c
39-a
40-a
41-e
42-d
43-a
44-e
45-b
46-a
47-b
48-e
49-c
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