Question 1

Which of the following instruments is used to precisely measure isotopes for radiometric dating?

Accepted Answer

A)  electron microprobe
B)  mass spectrometer
C)  geiger counter
D)  petrologic microscopeE) All of the above
F) B) and D)

Question 2

Major boundaries in the geologic time scale are often put there based on significant _____ events?

Accepted Answer

A)  tectonic
B)  volcanic
C)  mass extinction
D)  supercontinental breakupE) B) and D)
F) A) and B)

Question 3

A rock formed with 1000 atoms of a radioactive parent element,but contains only 250 radioactive parent atoms today.If the half-life for the radioactive element is one million years,how old is the rock?

Accepted Answer

A)  250,000 years old
B)  750,000 years old
C)  2 million years old
D)  4 million years oldE) B) and C)
F) C) and D)

Question 4

In order to reconstruct the geologic of rocks in a given region,geologists typically work

Accepted Answer

A)  with a single era.
B)  from oldest to newest.
C)  backward in time.
D)  forward in time.E) B) and C)
F) B) and D)

Question 5

Which life forms were first recognized in the fossil record?

Accepted Answer

A)  dinosaurs
B)  trilobites
C)  sharks
D)  humanoidsE) None of the above
F) B) and C)

Question 6

Both radiocarbon and potassium-argon dating share one specific problem that makes these methods difficult to use.What is that problem?

Accepted Answer

A)  Both have short half-lives.
B)  Both have parents that are too rare to measure accurately.
C)  The half-lives of both are poorly known.
D)  Both produce daughters that are in a gaseous state.E) A) and D)
F) B) and C)

Question 7

The study of the layers in sedimentary rock is known as

Accepted Answer

A)  stratigraphy.
B)  paleontology.
C)  sedimentation.
D)  geochronology.E) B) and C)
F) C) and D)

Question 8

Which of the following statements is false?

Accepted Answer

A)  Dikes are older than the rocks they cross-cut.
B)  Faults are younger than the rocks they cross-cut.
C)  Sills are younger than the rocks they cross-cut.
D)  Unconformities are younger than the layers they erode.E) A) and C)
F) B) and D)

Question 9

Almost nine-tenths of Earth's history occurs during the

Accepted Answer

A)  Phanerozoic.
B)  Archean.
C)  Paleozoic.
D)  Precambrian.E) B) and D)
F) A) and D)

Question 10

Carbon-14 has a half-life of approximately _______ years and is therefore suitable to dating objects younger than approximately_________years.

Accepted Answer

A)  4 million; 5 billion
B)  6 thousand; 70 thousand
C)  70 thousand; 6 thousand
D)  5 thousand; 50 thousandE) A) and D)
F) B) and D)

Question 11

Fossils are most common in which rock types?

Accepted Answer

A)  igneous
B)  metamorphic
C)  sedimentary
D)  Fossils are equally common in sedimentary,igneous,and metamorphic rocks.E) B) and C)
F) A) and D)

Question 12

The principle of superposition states that

Accepted Answer

A)  a fault is younger than the rocks it cuts.
B)  sediments are deposited as essentially horizontal layers.
C)  the present is the key to the past.
D)  undisturbed sedimentary layers get progressively younger from bottom to top.E) A) and C)
F) C) and D)

Question 13

Who came up with the principle of faunal succession?

Accepted Answer

A)  Charles Lyell
B)  William Smith
C)  Nicolaus Steno
D)  James HuttonE) A) and D)
F) A) and C)

Question 14

Geologic correlation of sedimentary rocks bounded above and below by unconformities is called

Accepted Answer

A)  sequence stratigraphy.
B)  paleomagnetic stratigraphy.
C)  chemical stratigraphy.
D)  sedimentary stratigraphy.E) B) and D)
F) A) and B)

Question 15

The first geologic map covering an entire country was for

Accepted Answer

A)  France.
B)  the United States.
C)  Russia.
D)  England.E) B) and D)
F) B) and C)

Question 16

A disconformity is _

Accepted Answer

A)  an erosional surface between horizontal layers of sedimentary rocks.
B)  an erosional surface between igneous and sedimentary rocks.
C)  a rock unit that does not contain fossils.
D)  a rock unit that is different from the units above or below it.E) A) and B)
F) A) and C)

Question 17

Which of the following is an erosion surface that separates two sets of sedimentary layers with nonparallel bedding planes?

Accepted Answer

A)  angular unconformity
B)  cross-bed
C)  disconformity
D)  nonconformityE) C) and D)
F) All of the above

Question 18

The absolute age of a geologic event in the rock record is

Accepted Answer

A)  the number of years that has elapsed between the event and the present day.
B)  the amount of time that has elapsed between the event and the beginning of Earth's history.
C)  the number of years that has elapsed between the event and the beginning of human civilization.
D)  the amount of time that has elapsed between the event and another similar geologic event.E) None of the above
F) All of the above

Question 19

Which of the following radioactive isotopes has the shortest half-life?

Accepted Answer

A)  carbon-14
B)  potassium-40
C)  rubidium-87
D)  uranium-238E) B) and C)
F) A) and D)

Question 20

Which of the following radioactive isotopes could be used to date very old (3 billion year old) rocks?

Accepted Answer

A)  uranium-238
B)  potassium-40
C)  uranium-235
D)  all of the aboveE) A) and B)
F) None of the above

Exam 8: Clocks in Rocks: Timing the Geologic Period

The study of the layers in sedimentary rock is known as

Correct AnswerverifiedShow Answer

Major boundaries in the geologic time scale are often put there based on significant _____ events?

Correct AnswerverifiedShow Answer

Carbon-14 has a half-life of approximately _______ years and is therefore suitable to dating objects younger than approximately_________years.

Correct AnswerverifiedShow Answer

Which of the following instruments is used to precisely measure isotopes for radiometric dating?

Correct AnswerverifiedShow Answer

Almost nine-tenths of Earth's history occurs during the

Correct AnswerverifiedShow Answer

The principle of superposition states that

Correct AnswerverifiedShow Answer

A disconformity is _

Correct AnswerverifiedShow Answer

In order to reconstruct the geologic of rocks in a given region,geologists typically work

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Which of the following is an erosion surface that separates two sets of sedimentary layers with nonparallel bedding planes?

Correct AnswerverifiedShow Answer

A rock formed with 1000 atoms of a radioactive parent element,but contains only 250 radioactive parent atoms today.If the half-life for the radioactive element is one million years,how old is the rock?

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Which of the following radioactive isotopes has the shortest half-life?

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Which of the following statements is false?

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Fossils are most common in which rock types?

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Which of the following radioactive isotopes could be used to date very old (3 billion year old) rocks?

Correct AnswerverifiedShow Answer

Geologic correlation of sedimentary rocks bounded above and below by unconformities is called

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Both radiocarbon and potassium-argon dating share one specific problem that makes these methods difficult to use.What is that problem?

Correct AnswerverifiedShow Answer

The first geologic map covering an entire country was for

Correct AnswerverifiedShow Answer

Who came up with the principle of faunal succession?

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Which life forms were first recognized in the fossil record?

Correct AnswerverifiedShow Answer

The absolute age of a geologic event in the rock record is

Correct AnswerverifiedShow Answer

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Carbon-14 has a half-life of approximately _ years and is therefore suitable to dating objects younger than approximately___years.

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