Earth Systems 3209
Test
Chapters 8
Name _______________
Multiple Choice. Choose the best answer for the following multiple choice questions. Write
the UPPERCASE letter of the correct answer on the answer sheet on page 6. [11 marks]
1. The task of matching up rocks of similar ages in different regions is known as
a) indexing
b) linking
c) superposition
d) correlation
e) succession
2. Fossils that are widespread geographically and are limited to a short span of time are referred to
as ________ fossils.
a) key
b) succeeding
c) relative
d) matching
e) index
3. A(n) ________ in the rock record represents a long period during which deposition ceased,
erosion removed previously formed rocks, and then deposition resumed.
a) absolute date
b) relative date
c) unconformity
d) superposition
e) inclusion
4. The process by which atomic nuclei spontaneously break apart (decay) is termed
a) ionization
b) reduction
c) radioactivity
d) fusion
e) nucleation
5. Rock layers that have been deposited essentially without interruption are said to be ________
strata.
a) included
b) abnormal
c) sequential
d) conformable
e) succeeding
6. The major units of the geologic time scale were delineated during the
a) 1700s
b) 1800s
c) 1900s
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7. The remains or traces of prehistoric life are known as
a) indicators
b) replicas
c) fissures
d) fossils
e) paleotites
8. A break that separates older metamorphic rocks from younger sedimentary rocks immediately
above them is a type of unconformity called a(n):
a) disconformity
b) contact unconformity
c) nonconformity
d) pseudoconformity
e) angular unconformity
9. "Most layers of sediments are deposited in a horizontal position" is a statement of the principle
of:
a) original horizontality
b) sediment
c) cross-cutting relationships
d) cross-bedding
e) fossil succession
10. Pieces of one rock unit contained within another are called:
a) intrusions
b) hosts
c) inclusions
d) interbeds
e) conformities
11. During radioactive decay, what will be the parent/daughter ratio after three half-lives?
a) 1:3
b) 1:4
c) 1:5
d) 1:6
e) 1:7
True/False. For the following true/false questions, if a statement is not completely true, mark
it false. Place a T for True and F for False on the answer sheet on page 6. [9 marks]
1. The entire geologic time scale was created using absolute dates.
2. Index fossils are useful for correlating the rocks of one area with those of another.
3. All rocks can be dated radiometrically.
4. When magma works its way into a rock and crystallizes, we can assume that the intrusion is
older than the rock that has been intruded.
5. During radioactive decay, as the percentage of radioactive parent atoms declines, the proportion
of stable daughter atoms decreases.
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6. In addition to being important tools for correlation, fossils are also useful environmental
indicators.
7. Most layers of sediment are deposited in a horizontal position.
8. No place on Earth has a complete set of conformable strata.
9. Index fossils are important time indicators.
Word Choice. Complete each of the following statements by selecting the correct response(s).
Write the correct response on the answer sheet on page 6. [13 marks]
1. The most useful fossils for geologic dating are called [index/parent] fossils.
2. Carbon-14 dating is used with [igneous/organic] materials.
3. With most isotopes used in radiometric dating, the ratio of the original isotope to its [emitted
particles/daughter product] is measured.
4. When rocks are deposited sequentially without interruption they are said to be
[sequential/conformable].
5. The best index fossils formed from organisms that had [narrow/wide] geographic ranges and
existed for [long/short] spans of time.
6. The entire geologic time scale was originally created using methods of [relative/absolute]
dating.
7. Fossils would be best preserved in [coarse/fine] sediments.
8. Isotopes produced by the decay of radioactive elements are called the [parent/daughter]
products.
9. Inclusions are [younger/older] than the rock they are found in.
10. Rocks from several localities have been dated at more than [three/five] billion years.
11. Angular unconformities are most likely to follow periods of [volcanism/folding and erosion].
12. [Igneous/Sedimentary] rocks are the least suitable for radiometric dating.
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Written Questions: Answer all questions on this paper.
1. Explain the difference between radiometric and relative dating. [2 marks]
Radiometric dating gives a numerical (absolute) age whereas relative dating does not.
The process/principles used in each type of dating are different. For example, relative dating uses
superposition, inclusions, and cross-cutting to determine relative age whereas radiometric dating
relies on the predictable decay of radioactive nuclei.
2. How are fossils helpful in geologic investigations? [2 marks]
Fossils are important for interpreting the geological past in that:
i. knowing the nature of life forms that existed at a particular time helps researchers
understand past environmental conditions. For example, fossils of animals with thick
shells capable of withstanding the pounding surf probably inhabited the shoreline whereas
the fossils of animals with thin, delicate shells inhabited the calmer offshore waters.
ii. they play a key role in correlating rocks of similar ages from different places. For
example, rock layers containing the same index fossils would be close in age even if the
rock layers were widely separated.
3. The diagram below represents the decay pattern of a radioactive isotope in an
igneous rock sample. The half life of the radioactive isotope is 2.3 million years.
Use the pattern to determine the age of the rock and show your working in the box
below. [3 marks]
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4. Use the diagram below to answer the questions that follow.
(i) List the geologic events, represented by letters A to K, from oldest to
youngest.
Oldest
Youngest
_____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____
(ii) Which type of unconformity is represented by K?
(iii) Explain how you know which letter identifies the oldest igneous rock unit.
“E” is older because Unit “G” cuts rock unit “E” (law of cross cutting) or igneous rock unit “G”
burns (contact metamorphism) rock unit “E”.
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Name ____________________
Multiple Choice
1.
2.
3.
4.
5.
6.
_____D
_____E
_____C
_____C
_____D
_____B
7. _____D
8. _____C
9. _____A
10. _____C
11. _____E
True/False
1.
2.
3.
4.
5.
_____F
_____T
_____F
_____F
_____F
6.
7.
8.
9.
Word Choice
1. index
2. organic
3. daughter product
4. conformable
5. wide
short
6. relative
7. fine
8. daughter
9. older
10. three
11. folding & erosion
12. Igneous
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_____T
_____T
_____T
_____T
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