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GEOLOGY 12
CHAPTER 8 TAKE-HOME QUIZ PART A
GEOLOGIC TIME AND THE FOSSIL RECORD
KEY
Score Part A= _______ / 54
¾ You will need copies of the following data booklet pages to complete parts of this test: Isotope
Pairs, Geologic Time Scale, Development of Life Through Time and Sample Fossils.
True or False
For each of the following, write T if the statement is true. If the statement is false, write F
T
1.
Geologists use both direct and indirect clues in order to find the age of a rock.
T
2.
"Jane is older than Sam." This statement is a measure of relative age dating.
T
3.
"Jane is 16 years old." This statement is a measure of absolute age dating.
T
4.
Erosional surfaces are examples of unconformities.
T
5.
The relative age of rocks or rock structures refers to the order in which they
were deposited.
T
6.
"Younger layers are on top of older layers" refers to the superposition rule.
T
7.
An index fossil is a fossil that is useful for indicating the period of time when the
sediment was deposited.
T
8.
Uranium 235 is a unstable isotope of uranium.
T
9.
The Law of Faunal Succession was most useful in providing a basis for
correlation of sedimentary units.
T
10.
The use of radiometric dating methods permits us to assign fairly accurate
approximate ages to rock units.
T
11.
Because half-lives of radioactive isotopes are well known, it is possible to
predict the rate at which an isotope will decay.
T
12.
A weakly metamorphosed rock may yield a radiometric date between the
original age of the rock and the time of metamorphism.
T
13.
Confidence in a radiometric date is particularly great when several different
isotopic systems yield the same date.
T
14.
The “type section” of a unit of the geologic time scale is often is named for the
locality in which it was first discovered.
T
15.
There are no known terrestrial rocks that have been preserved unchanged
since the earth formed.
T
16.
Layers of volcanic ash found between other rock layers often serve as good
geologic time markers because volcanic ash is usually deposited rapidly over a
very large area.
Multiple Choice: Circle the letter of the choice that BEST answers the question.
1.
Fossils that are useful in establishing the absolute ages of rocks
A.
B.
C.
D.
2.
The half-life of an element is
A.
B.
C.
D.
3.
are called index fossils
occupied only a small geographical area in Earth's history
contain abundant amounts of radioactive material
were once abundant and occupied a short geological time period
the time taken for one-half of a radioactive material to decay
the initial crystallization of radioactive materials
the time needed for half the mass of a rock to disappear
similar for all radioactive elements
The crosscutting rule states that
A.
B.
C.
D.
the strata of rocks are deposited from youngest to oldest
an event that disturbs a rock is younger than the rock layer itself
the crosscutting rule does not apply to igneous rooks
eroded surfaces occur following the deposition of rocks
Use the cross-section below to answer the next question.
4.
The possible age sequence of this section, from oldest to youngest is
A.
B.
C.
D.
5.
M
E
D
A
E
D
E
C
D
M
M
D
C
C
C
E
A
A
A
M
Layer M is an example of which geological principle?
A.
B.
C.
D.
the law of superposition
the crosscutting rule
older strata occupy the uppermost layers
the law of lateral continuity
6.
In a rock formation, clamshells, snail shells, and ammonites are found in several of the
layers. Only one of the layers contains fossils of brachiopods. The geologist studying the
formation concluded that
A.
B.
C.
D.
7.
According to recent estimates, the age of the Earth is believed to be
A.
B.
C.
D.
8.
the clamshells were deposited in an ancient shallow sea
the snail shells belong to an extinct marine species
the brachiopods found could be considered index fossils
not enough information was present and further investigation was needed
4.6 million years
45 million years
4.6 billion years
46 billion years
An unconformity is a surface within a sedimentary sequence where
A.
B.
C.
D.
there was possibly a period of non-deposition and/or extensive erosion.
erosion definitely did not occur.
there are fossils.
all of these choices
Use the following sketch of a geological cross section to answer the next two questions.
9.
The break in the time sequence of layers at N is called a(n)
A.
B.
C.
D.
normal fault.
reverse fault
discontinuity.
unconformity.
10. A correct sequence for some of the events in the cross section is
A.
B.
C.
D.
deposit of P, erosion at N, tilting.
erosion at N, deposit of P, tilting.
tilting, deposit of P, erosion at N.
deposit of P, tilting, erosion at N.
11. A rock contains a parent isotope with a half-life of one thousand years. Assuming that no
daughter atoms were initially present, after two thousand years, what is the ratio of
daughter atoms to parent atoms?
A.
B.
C.
D.
1:7
1:1
1:4
3:1
12. Which curve represents the stable daughter isotope?
A. curve X
B. curve Y
Use the following decay curve graph to answer the next question.
13. A rock sample used for radiometric dating contained a ratio of 3 stable daughter atoms for
1 parent atom. The age of the sample is most likely
A.
B.
C.
D.
1 million years.
3 million years.
6 million years.
12 million years.
14. A rock started out with 8000 atoms of parent radioisotope X and none of its daughter Y.
We now find in it 1000 atoms of X and 7000 of Y. The half-life of X is 10 million years. The
rock is _____ years old.
A.
B.
C.
D.
30 million
% Parent = 1:7 = 1/8 = 25% = 3HL
70 million
7000
The age cannot be determined from the information given.
15. Radiometric dating of rock surrounding an igneous intrusion using potassium-40/argon-40
(40K - 40Ar) is unreliable because potassium-40
A.
B.
C.
D.
has a long half-life.
has no stable daughter product.
has a gas as a daughter product.
is in very small amounts in rock.
16. Which of the following is most difficult to date radiometrically?
A.
B.
C.
D.
the time of crystallization of a pluton
the time of deposition of a sedimentary rock
the time of a strong metamorphic event
the age of a lava flow
17. The age of the earth is now determined by
A.
B.
C.
D.
radiometric dating of the oldest terrestrial rocks
use of fossils and the Law of Faunal Succession
dating of meteorites, which are believed to be the same age as the earth
dating the oldest sediments found on the continents
18. The era during which all of the following events occurred is the
A.
B.
C.
D.
Cenozoic.
Mesozoic.
Paleozoic.
Precambrian.
19. A major possible explanation for so few fossils being found in Precambrian rocks is that
during that period
A.
B.
C.
D.
no life existed
life forms lacked hard body parts which could be preserved
no sedimentary rocks were formed
life forms became extinct
Use the following geological cross section to answer the next question.
Lava flow - dated 200 m.y.
20. The period during which the sandstone layer would have been deposited is most likely the
A.
B.
C.
D.
21.
Cretaceous.
Jurassic.
Triassic.
Permian.
The subdivisions of the geologic time scale
A.
B.
C.
D.
22.
Which of the following represents the oldest time unit?
A.
B.
C.
D.
23.
Phanerozoic
Precambrian
Mesozoic
Quaternary
Subdivisions of the Precambrian
A.
B.
C.
D.
24.
were based principally on fossil evidence and sedimentary rocks
could not be established until radiometric dating methods had been developed
have been set up so that all eras are of equal length
all of the above
do not exist
have been difficult to establish because few fossils are found in Precambrian rocks
are unnecessary because the Precambrian spans a relatively short part of geologic time
all of the above
A layer of sandstone sits atop 350 million-year-old granite, and a 15 million-year-old basalt
dike cuts across both units. The sandstone is
A.
B.
C.
D.
over 350 million years old
between 350 and l5 million years old
younger than 15 million years
of completely unknown age
25.
The type section for rocks of the Cambrian period can be found in
A.
B.
C.
D.
26.
The basis for the subdivisions of the geologic time scale during the Phanerozoic Era is
A.
B.
C.
D.
27.
periods of intense, widespread metamorphism, igneous activity, and mountain building
approximately equal divisions of geologic time, as determined by radiometric ages
the appearance and disappearance (extinctions) of fossil species
the Principle of Original Horizontality
Which of the following radioactive isotopes would definitely NOT be appropriate for dating a
rock thought to be about 400 million years old
A.
B.
C.
D.
28.
the Jura Mountains of France
Wales or Cambria (latin), a part of Great Britain
the Grand Canyon
Cape Horn
carbon-14
thorium-232
uranium-238
uranium-235
A conglomerate along the California coast contains pieces of basalt which have been dated
as 18 million years old. How should we interpret this age?
A. It represents the time that the clasts of the conglomerate accumulated at the surface.
B. It represents the time that the clasts of the conglomerate were lithified (stuck together)
beneath the surface.
C. It represents the time at which the conglomerate was uplifted and exposed to
weathering.
D. It represents the time that the basalt crystallized from a lava flow.
29.
Which are characteristics of an index fossil?
A.
B.
C.
D.
30.
Which is the correct order for the changes in life that occurred during the Paleozoic era?
A.
B.
C.
D.
31.
wide geographic distribution and long geologic time range
wide geographic distribution and short geologic time range
narrow geographic distribution and long geologic time range
narrow geographic distribution and short geologic time range
amphibian, fish, invertebrate, reptile
fish, reptile, invertebrate, amphibian
invertebrate, fish, amphibian, reptile
reptile, invertebrate, amphibian, fish
Which is the most recent theory for the extinction of the dinosaurs?
A.
B.
C.
D.
Flesh-eating mammals ate the dinosaurs’ eggs.
Climatic changes eliminated the dinosaurs’ swamps.
Worldwide disease infected them.
An asteroid impact created dust that blocked sunlight.
32.
Replacement is a mode of fossil preservation whereby
A.
B.
C.
D.
33.
A reptile footprint in the upper surface of a mudstone is a(n)
A.
B.
C.
D.
34.
shell material undergoes recrystallization during diagenesis.
minerals introduced in solution replace original material as it dissolves or decays away
sediment fills a mold of the organic matter.
soft tissue is preserved as a carbon film.
trace fossil.
index fossil.
guide fossil.
extinct fossil.
The partial timeline below shows geologic periods paired with animal groups which were
dominant during that period. Which animal group is INCORRECTLY matched to its period?
A.
B.
C.
D.
Fish
Reptiles
Amphibians
Invertebrates
The Cambrian fossil creature (Hallucigenia) shown below was found near Field, B.C. The
highly unusual feature of the fossils of the Burgess Shale is the preservation of soft parts.
35.
Which of the following would NOT be necessary for the preservation of traces of soft parts
of an animal such as Hallucigenia?
A.
B.
C.
D.
36.
rapid burial in mud
elimination of oxygen
mineral rich solutions
exclusion of scavengers
When paleontologists compare Hallucigenia with modern organisms and theorize about the
function of the tubes and spines on the body, they are applying the principle of
A.
B.
C.
D.
evolution
creationism
uniformitarianism
faunal succession
The diagrams below show two models of evolution which explain how one species evolved
into different species.
37.
The models shown above, in order, are known as
A.
B.
C.
D.
gradualism and macroevolution.
progressive equilibrium and natural selection.
punctuated equilibrium and gradualism.
microevolution and successive speciation.
The diagram below shows how a primitive reptile has, over millions of years, evolved into
different types of Mesozoic reptiles, each living in a different environment.
38.
Changes of the type shown in this diagram can best be explained by
A.
B.
C.
D.
convergence.
natural selection.
adaptive radiation.
punctuated equilibrium.
To reinforce the concepts covered in this section of the quiz you must now complete the
Quizlab version. Both of these will count for marks. (Minimum Score = 80%.)