Deck 8: Timing the Geologic Record

Question 1

Units A, B, C, D, E, and F are sedimentary rocks. Unit G is granite.

-The horizontal line labeled X-X' is a(n) ______.

A) angular unconformity
B) contour
C) cross-bed
D) fault

Answer 1

A

Question 2

Units A, B, C, D, E, and F are sedimentary rocks. Unit G is granite.

-Which of the following units is the youngest?

A) unit A
B) unit B
C) unit C
D) unit F

Answer 2

A

Question 3

Units A, B, C, D, E, and F are sedimentary rocks. Unit G is granite.

-Which of the following units is the oldest?

A) unit A
B) unit B
C) unit C
D) unit F

Answer 3

D

Question 4

Units A, B, C, D, E, and F are sedimentary rocks. Unit G is granite.

-Which of the following events happened most recently?

A) deposition of unit C
B) deposition of unit F
C) deposition of unit D
D) tilting of units C, D, E, and F

Question 5

Units A, B, C, D, E, and F are sedimentary rocks. Unit G is granite.

-Which of the following statements is true?

A) Deposition of unit A occurred before deposition of unit B.
B) Erosion took place prior to deposition of unit B.
C) Unit C is younger than unit A.
D) The granite is older than unit F.

Question 6

Units A, B, C, D, and E are sedimentary rocks. The thick dark line is a fault.

-When did faulting occur?

A) between the deposition of A and B
B) between the deposition of C and D
C) between the deposition of B and C
D) between the deposition of D and E

Question 7

Units A, B, C, D, and E are sedimentary rocks. The thick dark line is a fault.

-What is the relative timing between faulting and intrusion of the granite?

A) Faulting occurred after the intrusion of the granite.
B) Faulting occurred before the intrusion of the granite.
C) Faulting and intrusion of the granite occurred at the same time.
D) The relative timing between faulting and intrusion of the granite cannot be determined from the information provided.

Question 8

Units A, B, C, D, and E are sedimentary rocks. The thick dark line is a fault.

-Which of the following units is the oldest?

A) unit A
B) unit C
C) unit E
D) the granite

Question 9

The founder of the principle of the faunal succession is ____________.

A) Sir James Hutton
B) Alfred Wegener
C) William Smith
D) Nicolaus Steno

Question 10

Consider three undeformed horizontal beds of sedimentary rocks. Which layer is the oldest?

A) upper layer
B) middle
C) lower

Question 11

The study of the history of ancient life based on the fossil record is called

A) paleontology.
B) anthropology.
C) biology.

Question 12

A geologic formation is a series of rock layers that

A) can be recognized and mapped as a distinctive unit.
B) has approximately the same physical properties and the same assemblage of fossils.
C) has all these properties.

Question 13

A nonconformity is a

A) rock unit that is different than units above or below it.
B) gap in the geologic record bounded below by metamorphic or igneous rocks and bounded above by sedimentary rocks.
C) rock unit that does not contain fossils.

Question 14

Units A, B, C, D, and F are sedimentary rocks. Unit E is an igneous rock.

-When did the faulting occur?

A) after deposition of unit A
B) after deposition of unit C and before deposition of unit B
C) cannot be determined from the information given

Question 15

Units A, B, C, D, and F are sedimentary rocks. Unit E is an igneous rock.

-Which of the following events happened most recently?

A) erosion of part of unit C
B) faulting
C) deposition of unit F

Question 16

Units A, B, C, D, and F are sedimentary rocks. Unit E is an igneous rock.

-Which is the oldest unit?

A) C
B) E
C) F

Question 17

Units A, B, C, D, and F are sedimentary rocks. Unit E is an igneous rock.

-The most likely explanation for the varying thickness of unit C on either side of the fault is that

A) more sediment was originally deposited on the left side of the fault.
B) sediment was eroded from the right side of the fault.
C) unit B is covering up part of unit C on the right side of the fault.

Question 18

Which type of unconformity has sedimentary rocks both above and below the unconformity surface?

A) angular unconformity
B) disconformity
C) both an angular unconformity and a disconformity

Question 19

What is the name of the scientist whose work laid the foundation for the modern science of stratigraphy?

A) Henri Becquerel
B) Nicolaus Steno
C) Charles Darwin

Question 20

Which of the following is the smallest division of geologic time?

A) eons
B) epochs
C) eras
D) periods

Question 21

Most periods in the geologic time scale are named for

A) geographic localities and distinguishing characteristics.
B) distinctive fossils.
C) catastrophic events.

Question 22

The oldest rock formation in the Grand Canyon is the

A) Bright Angel shale.
B) Tapeats sandstone.
C) Vishnu schist.

Question 23

What scientific avenue of investigation gave scientists the best estimate of the absolute age of the Earth?

A) paleontological dating
B) radiometric or isotopic dating
C) carbon dating

Question 24

Which of the following statements about rubidium-87 radiometric dating is true?

A) The number of radioactive rubidium-87 atoms in an igneous rock is constant.
B) The number of strontium-87 daughter products in an igneous rock is constant.
C) The rate at which rubidium-87 decays to strontium-87 is constant.

Question 25

-What is the best estimate for the age of point D?

A) 65 million years
B) 250 million years
C) 145 million years
D) 542 million years

Question 26

-What is the best estimate for the age of point E?

A) 1.5 billion years
B) 2.5 billion years
C) 3.0 billion years
D) 4.5 billion years

Question 27

-When did fossils of complex organisms (such as shells) first become abundant in the geologic record?

A) at point B
B) at point C
C) at point D
D) at point E

Question 28

-When did dinosaurs rule the Earth?

A) between A and B
B) between C and D
C) between B and C
D) between D and E

Question 29

If the Earth's history were compressed into a single calendar year, human beings would first have appeared on

A) November 30
B) December 25
C) December 31

Question 30

In which type of rocks are fossils most commonly found?

A) igneous
B) metamorphic
C) sedimentary

Question 31

Complete the following sentence. Two different isotopes of the same element share the same __________ but have a different _____________ from one another.

A) mass number, atomic number
B) atomic number, mass number
C) number of neutrons, number of protons
D) number of protons, number of electrons

Question 32

Which of the following materials is best suited for absolute dating using the radioactive decay of carbon-14?

A) A piece of 10 million-year-old granite
B) A piece of 10 million-year-old charcoal
C) A piece of 10 thousand-year-old granite
D) A piece of 10 thousand-year-old charcoal

Question 33

The half-life of any given isotope is a function of environmental temperature and pressure.

Question 34

Why was the advent of absolute dating important to the study of early Earth history?

A) Isotope half-lives are all too long to use them for dating young rocks.
B) There are few fossils in Precambrian rocks to use fossils for age control.
C) There are too few Precambrian rocks left to use fossils for age control.
D) Precambrian time is too short of an interval of geologic time to use fossils for age control.

Question 35

About what percent of Earth history occurs in the Precambrian (the time before the Cambrian Period)?

A) about 1%
B) about 15%
C) about 50%
D) about 90%

Question 36

Which is the earliest eon in Earth history?

A) Phanerozoic
B) Proterozoic
C) Hadean
D) Archean

Question 37

During which eon of Earth history did Earth's geodynamo begin?

A) Phanerozoic
B) Proterozoic
C) Hadean
D) Archean

Question 38

Earth's oldest fossils occur in sedimentary rocks that formed during which eon of geologic time?

A) Phanerozoic
B) Proterozoic
C) Hadean
D) Archean

Question 39

The start of which eon of geologic time is marked by the first appearance of shelly fossils in the geologic record.

A) Phanerozoic
B) Proterozoic
C) Hadean
D) Archean

Question 40

About how old is the oldest mineral grain ever dated?

A) About 800 million years old
B) About 1.5 billion years old
C) About 2.3 billion years old
D) About 4.4 billion years old

Question 41

During which eon of geologic time do fossils of organisms with cell nuclei first appear in the geologic record?

A) Phanerozoic
B) Proterozoic
C) Hadean
D) Archean

Question 42

The Phanerozoic Eon is divided into three eras of approximately equal length in time.

Question 43

Evidence suggests that liquid water existed on Earth more than four billion years ago.