Geology 10 Test 2 Practice
Multiple Choice
Identify the choice that best completes the statement or answers the question.
1. Which of the following is an organic chemical sedimentary rock that can be used directly as an energy
source?
a. Siltstone
b. Coal
c. Limestone
d. Shale
2. Which of the following types of metamorphism would be most likely to occur around a plutonic
intrusion?
a. Regional metamorphism
b. Contact metamorphism
c. Hydrothermal metamorphism
d. Subduction-zone metamorphism
3. On this cross-section, the numbers indicate possible DRILLING TARGETS for oil exploration. Which
one of them would be the best choice for finding oil?
a. 1
b. 2
c. 4
d. 3
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4. This graph shows the Pressure-Temperature-time (P-T-t) path of a metamorphic rock. Which of the
following types of metamorphism does it show?
a. Shock metamorphism
b. Subduction-zone metamorphism
c. Regional metamorphism
d. Contact metamorphism
5. You find a bed of sandstone, which sits on top of some gneiss, and both of these rocks are cut by an
igneous dike. The gneiss is 322 million years old, and the dike is 129 million years old. Which of the
following statements is most accurate?
a. The sandstone is just a little bit less than 322 million years old.
b. The sandstone is older than 322 million years old, and younger than 129 million
years old.
c. The sandstone is less than 322 million years old, but more than 129 million
years old.
d. The sandstone is older than 322 million years old, but not older than 129
million years old.
6. Which of the following rocks could NOT be dated radiometricallly?
a. Granite
b. Schist
c. Shale
d. Gneiss
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7. If you find an outcrop of sedimentary rock that shows MUD CRACKS on a bedding plane, what does
this tell you about the environment of deposition?
a. The sediments were deposited under a glacier.
b. It was deep marine
c. It was terrestrial (on-land, as opposed to underwater).
d. It was shallow marine, less than a few hundred feet of water depth.
8. What was the significance of the Cambrian Period in the history of life on Earth?
a. It was the first time that animals developed hard skeletal parts that fossilize
well.
b. It was the end of the era in which animals had hard skeletal parts that fossilize
well.
c. A very large mass extinction occurred at this time, wiping out most of the
organisms that live in the sea, and paving the way for the `Age of Dinosaurs’
that followed immediately after the Cambrian.
d. It was the time when the first life, in the form of bacteria, appeared on Earth.
9. If you’re looking for oil and/or natural gas, which of the following is NOT a necessary factor for
creating an economical accumulation of hydrocarbons?
a. A large amount of organic material in the source rock.
b. Heating of the area to high temperatures by plutonic rocks.
c. An impermable seal rock that prevents the hydrocarbons from reaching the
surface.
d. Sufficient porosity in the reservoir rock.
10. While analyzing source rocks for an oil company, you find yourself looking at some samples of shale.
What sort of sediment was this source rock before it was lithified?
a. Sand
b. There is a problem here - shale doesn’t usually make a good source rock.
c. Gravel
d. Mud
11. Imagine some metamorphic rocks that have NOT been exhumed. Which of the following things about
these rocks would make them difficult to study?
a. They are made of minerals that are not familiar to you from normal crustal
rocks.
b. They have hardly been metamorphosed at all.
c. They are not exposed at the Earth’s surface.
d. They have been metamorphosed so thoroughly that they have melted.
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12. While analyzing rock samples for an oil company, you are given some pieces of shale that might make
a good source rock. You decide that the original sediment had barely been buried - just enough to
lithify it, and not enough to heat it up very much at all. What problem does this cause for the creation
of oil?
a. The oil that’s generated from this source rock won’t be able to rise upward into
a trap, since it’s not dense enough.
b. Even if a trap structure exists, there won’t be a good sealing rock on top of it to
hold the oil in.
c. The organic matter didn’t mature; its atoms didn’t rearrange to form
hydrocarbons.
d. The pore spaces got entirely filled with cement, so there isn’t room for oil to
accumulate.
13. Which of the following is NOT generally a required factor for metamorphism?
a. Heat from plutonic intrusions and/or deep burial underneath other rocks
b. Deposition in a marine environment
c. Hot fluids that interact with the rock
d. Pressure from deep burial in the Earth
14. You collect a sample of igneous rock and count the radioative `parent’ atoms and the `daughter’
atoms that formed from the decay of the `parents’. There are 20 parent atoms, and 300 daughter
atoms. The half-life of the radioactive isotope is 10 million years. How old is the rocks?
a. 100 million years
b. 40 million years
c. 5 million years
d. 80 million years
15. Imagine some SLATE that is still underground, undergoing metamorphism. If the heat and pressure
increase, which type of metamorphic rock will this slate most likely become next?
a. Gneiss
b. Siltstone
c. Shale
d. Schist
16. If you were trying to CORRELATE two sequences of igneous rocks, which of the following would be
the most useful type of thing to find?
a. Extinct organisms
b. Unconformities
c. Index fossils
d. Fossils of animals with hard skeletal parts
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17. Imagine that you find some foliated metamorphic rock, like slate or schist. Which of the following
things was probably the MOST necessary for the formation of the foliation?
a. The rock must have formed near a divergent plate boundary, where a continent
was starting to rift apart.
b. The rock was deeply buried beneath other rocks, exposing to high pressure.
c. The original rock was composed of several different types of minerals, allowing
for a more diverse set of metamorphic minerals to form.
d. Unevenly-distributed pressure, which was greater from some directions than
others.
18. For these cross-sections, what is the direction to YOUNGER beds for each drawing?
a. LEFT, RIGHT, LEFT, LEFT
b. RIGHT, LEFT, RIGHT, No way to tell
c. RIGHT, RIGHT, LEFT, RIGHT
d. LEFT, LEFT, RIGHT, No way to tell
19. Looking at the same cross-sections from the `direction to younger’ question, which of the four
cross-sections shows a transition from MARINE to NON-MARINE deposition?
a. D
b. B
c. C
d. A
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20. Which of these is the best `shorthand’ statement of the Principle of Uniformitarianism?
a. `The present is the key to the past’
b. `The Moon is a Rosetta Stone for the solar system’
c. `Ancient rocks are identical to modern rocks’
d. `The older the rocks, the more fossils of extinct species’
21. While visiting the African country of Namibia, you look down into the Fish River Canyon, where you
see a squence of sedimentary`cover’ rocks sitting atop a `basement’ of plutonic and metamorphic rocks.
Based on this view, what can you say about the basement-cover contact in this area?
a. Nothing definitive can be said at this point - you need to go into the canyon
and collect fossils.
b. The basement rocks must be younger than the cover rocks.
c. It must have formed during the Cambrian period.
d. It is an unconformity.
22. If you find an outcrop of sandstone that shows ripple marks, which of the following is the most
reasonable statement about the environment of deposition?
a. We’d need fossils to be sure of the depositional environment.
b. This sand was deposited as part of a desert sand dune.
c. The environment of deposition was at the bottom of a deep ocean.
d. This sand was deposited as part of a shoreline environment.
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Short Answer
23. This cross-section shows a deep canyon. Highlight all of the contacts that have to be unconformities.
Make sure to only highlight those contacts that HAVE to be unconformities.
Next: A friend of yours says that this would be a good place to look for dinosaur fossils. Is this correct?
Why or why not?
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ID: A
Geology 10 Test 2 Practice
Answer Section
MULTIPLE CHOICE
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SHORT ANSWER
23. ANS:
No, it’s not a good place to look for dinosaur fossils, since Mesozoic rocks are not present here. They
were either never deposited, or else were eroded before the deposition of the Cenozoic sedimentary
rocks.
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