Earth: An Introduction to Physical Geology, 11e (Tarbuck)
Chapter 9 Geologic Time
9.1 Multiple-Choice Questions
1) What is the definition of relative dating?
A) Putting events in order from first to last
B) Using radioactive materials to determine an age
C) Counting tree rings to determine an age
D) Calculating dates based on the theory of relativity
2) Which scientist is credited with developing the Law of Superposition?
A) James Ussher
B) Charles Lyell
C) James Hutton
D) Nicholas Steno
3) A(n) ________ is a type of unconformity with parallel beds above and below the erosional
surface.
A) Fossil conformity
B) Nonconformity
C) Disconformity
D) Angular unconformity
4) What is a fossil?
A) Evidence of past life that can include skeletal as well as trace material
B) Only the hard parts of a skeletal structure that have been preserved
C) Mudcracks preserved in sedimentary rock
D) A really old geologist
5) ________ is the scientific study of fossils.
A) Quaternary Geology
B) Volcanology
C) Geomorphology
D) Paleontology
6) A mammoth frozen in the Arctic tundra of Siberia would be an example of which type of
fossilization?
A) Permineralization
B) Mummification
C) Replacement
D) Carbonization
7) A worm burrow is an example of which type of fossilization?
A) Mummification
B) Cast and Mold
C) Carbonization
D) Trace Fossil
8) What is correlation?
A) Dividing up rock layers into new ones based on mineral content
B) Matching up rocks of similar age in different regions
C) Putting events in order from first to last
D) Matching up continental coasts based on matching shapes
9) The Principle of ________ states that organisms succeed one another in a definite,
determinable order that can be used to recognize a specific time period.
A) Correlation
B) Superposition
C) Fossil Succession
D) Lateral Continuity
10) When correlating rock between widely separated areas or between continents, what feature
do geologists rely on the most?
A) Rock type
B) Sedimentary structures
C) Fossils
D) Mineral content
11) ________ was the English engineer and canal builder that observed that sedimentary strata in
widely separated areas could be identified by their distinctive fossil assemblages.
A) Isaac Newton
B) William Smith
C) Charles Lyell
D) Charles Darwin
12) What is an index fossil?
A) Organisms that existed for a vast period of time and are representative of an era
B) Organisms that are restricted to one small, geographic setting
C) Trace fossils that define a colony of organisms
D) Organisms that were geographically widespread but limited to a short span of geologic time
13) What is an isotope?
A) An atom that has more or fewer neutrons than it should
B) An atom that has more or fewer electrons than it should
C) An atom that has double the protons of a stable atom
D) A nucleus of an atom that has split during the decay process
14) If 235U has 92 protons, how many neutrons does it have?
A) 25
B) 92
C) 143
D) 235
15) ________ is a technique where the decay rate of radioactive isotopes is measured and used to
determine the age of a geologic material.
A) Electron Capture
B) Radiometric Dating
C) Ion Exchange
D) Half-Life
16) What is the definition of a half-life?
A) The parent isotope half of a radiometric dating pair
B) Half the time it takes for the parent isotope to decay to the daughter
C) The time it takes for half of the parent isotope to decay to the daughter
D) Half of the alpha particles necessary to decay at a steady rate
17) You are an archaeologist researching artifacts left behind by Francisco Pizzaro’s conquest of
Peru in the 1530s. In order to confirm the authenticity of the leather artifacts, you are performing
radiometric dating using an isotope pair that has a half-life of 250 years. In order for the artifacts
to date back to the time of Pizzaro’s conquest, approximately how much original radioactive
isotope must be left in the artifacts?
A) 50%
B) 25%
C) 75%
D) 12.5%
18) Which era are we currently in?
A) Mesozoic
B) Precambrian
C) Paleozoic
D) Cenozoic
19) What does “zoic” in the eras of the Geologic Time Scale refer to?
A) Life
B) Water
C) Rock
D) Fossilization
20) ________ is a term used to define 88% of Earth’s history prior to the start of the Paleozoic
Era.
A) Quaternary
B) Precambrian
C) Paleogene
D) Jurassic
9.2 True/False Questions
1) Numerical dating is putting events in order from first to last.
2) By putting events in order, scientists can use the order to determine how long ago certain
geologic events took place.
3) In cast and mold fossilization, the cast is the hollow space in the rock that subsequently
becomes filled with mineral matter.
4) Rapid burial is an important condition favoring preservation.
5) The fossil record is biased toward preserving organisms with hard parts.
6) A neutron is a combination of an electron and a proton.
7) All isotopes are unstable.
8) Carbon-14 dating is useful for paleontologists researching dinosaurs.
9) The oldest rocks on Earth date back to 4.28 billion years old and were found in western
Australia.
10) Hadean is an informal term used by many geologists to refer to the earliest interval of Earth’s
history.
11) The first life on Earth developed during the Cambrian Period.
12) A detrital sedimentary rock can be radiometrically dated because the clasts formed at the
same time as the rock.
9.3 Short Answer Questions
1) The Mississippi River cuts through Silurian-aged dolomite between northwestern Illinois and
eastern Iowa. Which is older? How do you know?
2) The white granite of the Idaho Batholith near Boise, ID contains dark gray xenoliths of
metamorphic material. Which is older? How do you know?
3) Which of the following would make the best index fossil and why: Olenellus (522-510 million
years ago), Flexicalymene (~490-418 million years ago), and Phacops (~418-360 million years
ago).
4) What is the different between an index fossil and a fossil assemblage?
5) A Devonian-aged limestone contains fossils of brachiopods and bryozoans. What do these
fossils indicate about the environment during the Devonian Period?
6) In radioactive decay, an unstable ________ isotope will decay into a stable ________ isotope.
7) What is the ratio of parent atoms to daughter atoms after three half-lives?
8) What is the ultimate source for naturally occurring Carbon-14?
9) Name the periods of the Paleozoic Era in order from oldest to youngest.
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9.4 Matching Questions
Match the relative dating principles with the correct definition.
A) Missing time
B) Chunks of weathered rock are older than the rock they are contained in
C) Sedimentary layers/lava flows are deposited in flat layers
D) Rock extend in all directions until they reach the edge of a basin or pinch out
E) The oldest is on the bottom, the youngest on top
F) Faults, fractures are younger than the rocks they cut through
1) Superposition
Diff: 1
Bloom’s Taxonomy: Knowledge
Global Sci Out: 7
Section: 9.1 – Creating a Time Scale – Relative Dating Principles
Focus/Concepts: 9.1
Earth Science LO: 2.1 – Earth’s rocks and other materials provide a record of its history.
2) Original Horizontality
Diff: 1
Bloom’s Taxonomy: Knowledge
Global Sci Out: 7
Section: 9.1 – Creating a Time Scale – Relative Dating Principles
Focus/Concepts: 9.1
Earth Science LO: 2.1 – Earth’s rocks and other materials provide a record of its history.
3) Lateral Continuity
Diff: 1
Bloom’s Taxonomy: Knowledge
Global Sci Out: 7
Section: 9.1 – Creating a Time Scale – Relative Dating Principles
Focus/Concepts: 9.1
Earth Science LO: 2.1 – Earth’s rocks and other materials provide a record of its history.
4) Cross-Cutting Relationships
Diff: 1
Bloom’s Taxonomy: Knowledge
Global Sci Out: 7
Section: 9.1 – Creating a Time Scale – Relative Dating Principles
Focus/Concepts: 9.1
Earth Science LO: 2.1 – Earth’s rocks and other materials provide a record of its history.
5) Unconformities
Diff: 1
Bloom’s Taxonomy: Knowledge
Global Sci Out: 7
Section: 9.1 – Creating a Time Scale – Relative Dating Principles
Focus/Concepts: 9.1
Earth Science LO: 2.1 – Earth’s rocks and other materials provide a record of its history.
6) Inclusions
Diff: 1
Bloom’s Taxonomy: Knowledge
Global Sci Out: 7
Section: 9.1 – Creating a Time Scale – Relative Dating Principles
Focus/Concepts: 9.1
Earth Science LO: 2.1 – Earth’s rocks and other materials provide a record of its history.