Deck 9: Geologic Time

Question 1

This photograph shows an upper light-colored conglomerate and a lower dark basalt. Which of the following statements is true?

A) the conglomerate is older because it overlies the dark basalt
B) the conglomerate is younger because it contains clasts of the dark basalt
C) the basalt is younger because it is crosscut by fractures filled with conglomerate
D) none of these

Answer 1

B

Question 2

Which of the four numbered features on this figure is the youngest?

A) 1
B) 2
C) 3
D) 4

Answer 2

D

Question 3

Which sequence of numbers reflects the order in which the layers were deposited?

A) 1, 2, 3, 4
B) 1, 3, 4, 2
C) 4, 3, 2, 1
D) 4, 3, 1, 2
E) none of these

Answer 3

A

Question 4

What type of feature is represented by the boundary between geologic units 2 and 3?

A) cleavage
B) unconformity
C) anticline
D) joint

Question 5

Who came up with the concept that geologic processes operating at present are the same processes that operated in the past?

A) Charles Darwin
B) James Hutton
C) Nicolaus Copernicus
D) Nicolaus Steno

Question 6

Which principle of relative dating can be used at Siccar Point in Scotland to determine that the rocks below the unconformity were tilted to vertical before erosion occurred?

A) Original horizontality
B) Contact effects
C) Lateral continuity
D) Inclusions

Question 7

Which principle can be used by a geologist to determine that the rocks shown in the photograph have not been deformed since they were deposited?

A) Original horizontality
B) Superposition
C) Cross-cutting relations

Question 8

Which principle can be used to determine the relative age of an igneous intrusion called a dike?

A) cross-cutting relations
B) superposition
C) original horizontality

Question 9

Which of the four numbered features on this figure is the oldest?

A) 1
B) 2
C) 3
D) 4

Question 10

What is the main geologic feature for which Siccar Point in Scotland is famous?

A) a boundary between steep gray layers below and gently dipping red layer above
B) an unconformity
C) an ancient erosion surface
D) all of these
E) none of these

Question 11

This photograph shows an upper unit with fragments and a lower unit with tilted layers. Which of the following statements is true?

A) the upper unit is younger because it is on top
B) the upper unit is younger because it contains pieces of the underlying unit
C) the lower unit is older because it was tilted and eroded before deposition of the upper unit
D) all of these

Question 12

Which principle is used to determine the age of rocks by ordering them from oldest on the bottom to the youngest on the top?

A) superposition
B) cross-cutting
C) inclusions
D) unconformities

Question 13

Where are the oldest rocks in the column of sedimentary rocks shown in the diagram?

A) At the bottom
B) At the top
C) In the middle

Question 14

Which numbered layer in this photograph represents the youngest layer?

A) 1
B) 2
C) 3
D) 4

Question 15

Where is the oldest layer in this tilted sequence of sedimentary rocks?

A) at the top of the hill in the center of the photograph
B) the darkest layers will be the oldest
C) the layers on the lower left part of the photograph
D) the layers on the right of the photograph

Question 16

This photograph shows light-colored granite and darker diorite both igneous rocks). Which of the following statements is true?

A) the light-colored unit is younger because granite is more continental than diorite
B) the diorite is older because its weathered surfaces are darker
C) the granite is younger because it crosscuts the diorite
D) all of these

Question 17

James Hutton inferred that the rocks below the contact at Siccar Point were vertical gray sandstone and shale and the rocks above were gently dipping red sandstone and conglomerate. Therefore, the histories of these rocks:

A) are different
B) are the same
C) are not able to be interpreted

Question 18

What type of feature is shown in this photograph of Siccar Point, Scotland?

A) monocline
B) thrust fault
C) normal fault
D) unconformity

Question 19

Which of the four sedimentary layers in this figure is the oldest?

A) the layer on top
B) the layers in the middle
C) the layer on bottom
D) there is not enough information to tell

Question 20

Which numbered layer in this photograph represents the oldest layer?

A) 1
B) 2
C) 3
D) 4

Question 21

What is the youngest event represented in this block diagram?

A) formation of the lowest layer
B) deposition of the top layer
C) erosion of a canyon by a river
D) retreat of the seas

Question 22

Which type of unconformity is produced when layers of sandstone and conglomerate bury an eroded surface of an igneous or metamorphic rock?

A) nonconformity
B) angular unconformity
C) disconformity

Question 23

What is a principle we use to determine the age of a landscape surface?

A) A landscape surface must be older than any rocks onto which it is carved.
B) A landscape surface is younger than any rock that is deposited on top of the surface.
C) The highest river terrace is probably the youngest in age.
D) A surface with a well-developed soil is probably older than a surface with no soil.

Question 24

The geologic relationships in this figure indicate that the lava flow:

A) pushed the trees over
B) overlies an angular unconformity
C) is younger than the landscape surface partially covered by the lava flow
D) that materials beneath the lava flow were uplifted from great depth

Question 25

Which is the last step in formation of a typical landscape?

A) Erosion
B) Deposition of sedimentary layers
C) Lithification into sedimentary rocks

Question 26

What kind of geologic feature is shown in this photograph?

A) contact metamorphism
B) unconformity
C) desert varnish
D) desert pavement
E) none of these

Question 27

Which principle of relative age dating can be used to determine when the river formed on the landscape?

A) cross-cutting relations
B) inclusions
C) original horizontality
D) superposition

Question 28

Which of the following is NOT something we can learn by determining isotopic ages?

A) the age of a volcanic eruption
B) the age when a rock is uplifted toward the surface
C) the age of material from which clasts in a sedimentary rock were derived
D) the cooling history by using different types of isotopic ages
E) we can determine all of these

Question 29

The highest surface on this figure is a river terrace. This terrace:

A) is older than the modern river channel
B) formed sometime in the past
C) predates erosion down to the present level
D) all of these

Question 30

If a rock started with 1,000 atoms of a parent but now contains 250 atoms, how many half lives have passed?

A) .25 half lives
B) .5 half lives
C) 1 half life
D) 2 half lives
E) there is no way to tell

Question 31

What kind of geologic feature is shown in this photograph?

A) contact metamorphism
B) unconformity
C) desert varnish
D) desert pavement
E) none of these

Question 32

The fossil fern in this photograph probably indicate that the rock was deposited:

A) by the wind
B) in the deep ocean
C) in the shallow ocean
D) on land

Question 33

The impressions of fossil shells in this photograph probably indicate that the rock was deposited:

A) by the wind
B) in the sea
C) in a dry climate
D) in a forest

Question 34

Isotopes that decay slowly are used to date:

A) ancient rock
B) recent lava flows
C) prehistoric cultural sites

Question 35

How does an angular unconformity form?

A) rocks are folded into an angle and the top is removed by faulting
B) older rocks are tilted, eroded, and overlain by younger rocks
C) rock layers are turned upside down at an angle
D) angular rocks are deposited on top of flat-lying layers
E) any of these

Question 36

This figure shows a disconformity between an upper dark layer being deposited by the sea) and a lower light-colored layer. What happened to form this disconformity?

A) The lower layers were tilted and untilted before deposition of the upper layers.
B) The boundary between the two units indicates that for a time there was either erosion or no deposition.
C) The lower limestones were converted into another rock type by seawater.
D) The upper layer must have been deposited by volcanic eruptions.

Question 37

Missing geologic time caused by erosion is called a an):

A) unconformity
B) fold
C) igneous intrusion

Question 38

If the contact between the upper light-colored sedimentary layers and the lower dark-colored metamorphic rocks is a depositional contact, what type of feature is present?

A) a surface representing missing geologic time
B) an angular unconformity
C) an ancient erosion surface
D) all of these

Question 39

In this photograph, Paleozoic sandstone rests depositionally on Precambrian granite. What events must have occurred before deposition of the sandstone?

A) uplift of granite to the surface
B) solidification of granite at depth
C) formation of an erosion surface
D) all of these
E) none of these

Question 40

The term half life represents the time it takes:

A) to dissolve half of the atoms in the lattice
B) for the parent atoms to decay into atoms half their original size
C) for half of the parent atoms to decay into daughter atoms
D) for the Sun to decrease its size by 50 percent

Question 41

Which of the following features look like fossils but are not?

A) footprints from dinosaurs and other creatures
B) burrows excavated by worms and other creatures and filled by other sediment
C) leaves and other plants formed on land
D) dark minerals that grow in branching patterns
E) all of these are fossils

Question 42

This figure shows the main subdivisions of the geologic timescale. Which of these is the Mesozoic?

A) A
B) B
C) C
D) D

Question 43

The contact at the base of unit F in both columns:

A) is a disconformity
B) represents erosion or no deposition
C) represents some missing time
D) all of these

Question 44

What factors are the most critical in determining whether a fossil is preserved?

A) the age of the fossil and the age of sediments in which it is preserved
B) the temperature of the granite and how fast it cooled
C) whether the creature had hard parts and how fast it was buried
D) the color of the original organism compared to the color of the sediments in which it is found
E) whether the creature was a predator or was prey

Question 45

This figure shows the main subdivisions of the geologic timescale. Which of these is the Paleozoic?

A) A
B) B
C) C
D) D

Question 46

Which of the following is the earliest oldest) chapter of geologic time?

A) Cenozoic
B) Mesozoic
C) Paleozoic
D) Precambrian

Question 47

Unit C is present in the left column but not the right column because:

A) rocks in the right column were tilted and eroded
B) it was not deposited or was eroded away
C) it has different kinds of fossils than rocks in the right column
D) all of these

Question 48

This figure shows two sections of rocks. What is the youngest unit?

A) unit 1
B) unit 4
C) unit 6
D) unit 9
E) none of these

Question 49

In which of the following time periods were mammals the dominant type of life?

A) Cenozoic
B) Mesozoic
C) Paleozoic
D) Precambrian

Question 50

Which of the following time periods were dinosaurs the dominant creatures?

A) Cenozoic
B) Mesozoic
C) Paleozoic
D) Precambrian

Question 51

Which of the following is NOT a way in which fossils can be preserved?

A) They can be replaced by hard materials, such as silica.
B) They can be buried and decay, leaving a cavity in the rock.
C) They can be preserved in ancient tree sap.
D) They can be too small to see but can build diagnostic features in the rocks.
E) All of these are ways a fossil can be preserved.

Question 52

In which of the following time periods did coral, clams, fish, plants and insects become abundant?

A) Cenozoic
B) Mesozoic
C) Paleozoic
D) Precambrian

Question 53

A hypothesis that explains how new organisms or new characteristics can appear suddenly in the fossil record is called:

A) punctuated equilibrium
B) natural selection
C) evolution

Question 54

To what does the term evolution refer?

A) observed changes in the fossil record
B) to one or more theories that help explain observed changes
C) as a general term to describe how something, such as a landscape, has changed over time
D) all of these

Question 55

Why don't these two sequences of fossil-bearing rocks match exactly?

A) they represent different parts of geologic time
B) one section was tilted but not the other
C) they have different histories of erosion and deposition
D) one represents a transgression whereas the other represents a regression

Question 56

This figure shows two sections that represent the same age range and contain some of the same fossils. If you compare the two sections, what conclusions do you come to?

A) Some of the fossils must have had a limited geographic distribution.
B) Some units were deposited in the left section but not in the right one or were eroded away.
C) The thickness of the units are consistent between the two sections.
D) All of these.
E) None of these.

Question 57

This figure shows the main subdivisions of the geologic timescale. Which of these is the Cenozoic?

A) A
B) B
C) C
D) D

Question 58

Which factor would help ensure survival of one species over another?

A) Adaptable to environmental change
B) Being a food source for other animals
C) Having to compete for sparse resources

Question 59

This figure shows the main subdivisions of the geologic timescale. Which of these is the Precambrian?

A) A
B) B
C) C
D) D

Question 60

Which of the following chapters in geologic time occurred before there were abundant animals with hard parts?

A) Cenozoic
B) Mesozoic
C) Paleozoic
D) Precambrian

Question 61

Some fossil species are of little value to geologists for correlation because:

A) they existed for a short period of geologic time
B) they were widespread
C) they existed for a long period of geologic time

Question 62

The oldest known rock found on Earth is dated at:

A) 1 million years old
B) 500 million years old
C) over 4 billion years old

Question 63

What would fossil ages from the geologic timescale and an isotopic age on the granite tell us about the age of the unconformity?

A) The unconformity is older than the isotopic age of the granite.
B) The unconformity is older than the age assigned to the fossils.
C) The granite is younger than the unconformity.
D) It is not possible to have fossils preserved so close to granite.
E) None of these.

Question 64

This figure shows the geologic timescale. Which period listed below would be part of the Mesozoic?

A) Neogene
B) Jurassic
C) Pennsylvanian
D) Mississippian
E) Cambrian

Question 65

In geology, determining time equivalency in rocks is called:

A) correlation
B) corresponding
C) continuity

Question 66

Which of the following is NOT accurately dated at between 4 and 4.6 billion years old?

A) the oldest dates on mineral grains on Earth
B) age of the oldest meteorites
C) age of moon rocks returned to Earth and dated
D) isotopic ages on Earth's oldest known fossil shell

Question 67

This figure shows the geologic timescale. Which period listed below would be part of the Cenozoic?

A) Neogene
B) Jurassic
C) Triassic
D) Pennsylvanian
E) Cambrian

Question 68

What would fossil ages from the geologic timescale tell us about the age of this unconformity?

A) The unconformity is younger than the fossil ages on the tilted bed.
B) The unconformity is older than the fossil ages in layers above the unconformity.
C) The amount of time represented by the unconformity can be approximately bracketed by the ages of the fossils above and below.
D) All of these.

Question 69

Finding several species of fossils, rather than just one, in the same rock layer is more useful to geologists because:

A) It indicates the sediments must have been deposited at the same time when all the species were present.
B) If some of the fossils are broken, others could be used as index species.
C) If the conditions were not right for fossilization for one species, maybe the conditions were better for other fossil species.

Question 70

How would we use isotopic ages to infer the ages of the upper and lower unit in this diagram?

A) The lower unit would be younger than an age on the crosscutting dike.
B) The upper unit would be older than an age determined on pebbles of the dike in that unit.
C) The dike is younger than the lower unit but older than the upper unit.
D) An age on the dike would not help us because it is an igneous rock.

Question 71

This figure shows the geologic timescale. Which period listed below would be part of the Paleozoic?

A) Neogene
B) Paleogene
C) Jurassic
D) Triassic
E) Cambrian

Question 72

Upon what basis were the upper and lower boundaries of the Mesozoic Era defined?

A) dramatic changes in the color of the rocks from green to tan
B) major episodes of mountain building
C) abrupt changes in the types of fossils, representing mass extinctions
D) the discovery that a meteoroid impact may have killed the dinosaurs

Question 73

Which of the following forms different layers from season to season and can be used to determine how many years the layers represent?

A) tree rings
B) layers in ice cores
C) varves
D) all of these

Question 74

This figure shows the geologic timescale. Which period listed below would be part of the Paleozoic?

A) Permian
B) Pennsylvanian
C) Mississippian
D) Cambrian
E) all of these

Question 75

The oldest rocks and minerals on Earth's surface have been found in Canada and Australia and are from the:

A) Precambrian Era
B) Paleozoic Era
C) Mesozoic Era
D) Cenozoic Era

Question 76

What defines the boundaries between each of the three eras in the geologic timescale?

A) Two great mass extinctions
B) The age of the Earth divided by three
C) A decision by the Geological Society of America
D) Principles of relative dating

Question 77

Which of the following is evidence that Earth's history is not short?

A) millions of layers of light- and dark-colored sediment that record yearly cycles
B) rates of seafloor spreading compared to the width of the Atlantic Ocean
C) a 4-billion-year age on a rock in Canada
D) thousands of isotopic ages measured by different methods
E) all of these

Question 78

This figure shows two sections that partially overlap in age. Dashed lines show how the two sections correlate. What can you conclude from these correlations?

A) the oldest unit is unit 4
B) the youngest unit is unit 6
C) the rate at which unit 5 was deposited was constant across the area
D) the left section represents older rocks than the right section
E) none of these

Question 79

Which of the following collection of fossils would be LEAST useful for determining the age of a section of rocks?

A) fossils that are large and distinctive
B) fossils that are widely distributed across different parts of Earth
C) the fossil of a family of creatures that lived unchanged for a very long time
D) index fossils

Question 80

The geologic timescale details and divides geologic time based upon:

A) fossil data
B) rock thicknesses
C) unconformities