Deck 11: Geologic Time

Question 1

The principle of cross- cutting relationships which states that a geologic feature that cuts across another feature must be younger than the feature it cuts is important because______ .

A) it provided a way to recognize if rocks had been deformed
B) it provided a tool for sorting out the relative timing of various geologic events
C) it allowed geologists to correlate rock units over large distances
D) it showed that igneous rocks were younger than sedimentary rocks

Answer 1

it provided a tool for sorting out the relative timing of various geologic events

Question 2

Who is credited with formulating the doctrine of uniformitarianism?

A) Lyell
B) Playfair
C) Aristotle
D) Hutton

Answer 2

Hutton

Question 3

An unconformity is a buried______ .

A) fault or fracture with older rocks above and younger rocks below
B) fault or fracture with younger strata above and older strata below
C) surface of erosion separating younger strata above from older strata below
D) surface of erosion with older strata above and younger strata below

Answer 3

surface of erosion separating younger strata above from older strata below

Question 4

One reason that Catastrophism was popular was______

A) there were many real catastrophes, like earthquakes and volcanic eruptions, to support the Catastrophism idea
B) Ussher's estimated age of the earth required catastrophic events to form mountains and canyons
C) Hutton's observations of great geologic time could not explain the rise of mountains or formation of deep canyons
D) everyone loves a disaster and as a result, the hypothesis that supported disasters was a favorite

Question 5

The basic concept of Uniformitarianism is ______ .

A) geology changes constantly but the rules that control those transformations do not change
B) evolution, plate tectonics, and similar theories are all related and can be viewed as the grand theory of Uniformitarianism.
C) there is a predictable way that the laws of nature change over time and we are beginning to understand them
D) geology has not changed since Earth was formed but other things do change
E) nothing has changed since Earth was formed

Question 6

One of the primary goals of geology is to ______.

A) develop a comprehensive relationship between fossils and geologic formations
B) identify all of the rocks on the surface of Earth
C) understand the role of plate tectonics in Earth's evolution
D) understand the history of Earth
E) determine the role of meteorites in the decline of species over time

Question 7

Unconformities that represent a break in the geologic record of deposition are geologically significant______.

A) they represent a period of erosion in the region
B) they give an indication of sea level rise within an ocean basin
C) they cannot be mapped
D) the fossils found in the unconformities can be used to correlate global time period

Question 8

If you observe an angular unconformity, you would infer that the region had experienced ______.

A) deposition in shallow water, uplift or lowering of sea level enough to expose the rocks to erosion and non- deposition for a period of time, and subsequent resubmergence of the remaining sedimentary units where they experience new deposition
B) intrusion of igneous rocks into a depositional setting, forcing the sedimentary layers upward and possibly deforming them, followed by subsidence of the remaining sedimentary layers and renewed deposition
C) uplift and tilting of sedimentary units that exposes them to erosion over a period of time with subsequent renewed deposition
D) deposition of sedimentary layers on crystalline igneous or metamorphic rocks that are exposed at the surface of the earth

Question 9

An important tool in understanding the actual numerical dates of past geologic events is______ .

A) radioactivity
B) unconformities
C) fossils
D) depositional rates
E) cross- cutting relationships

Question 10

If you observe a disconformity, you would infer that the region had experienced______ .

A) deposition in shallow water, uplift or lowering of sea level enough to expose the rocks to erosion and non- deposition for a period of time, and subsequent resubmergence of the remaining sedimentary units where they experience new deposition
B) uplift and tilting of sedimentary units that exposes them to erosion over a period of time with subsequent renewed deposition
C) deposition of sedimentary layers on crystalline igneous or metamorphic rocks that are exposed at the surface of the earth
D) intrusion of igneous rocks into a depositional setting, forcing the sedimentary layers upward and possibly deforming them, followed by subsidence of the remaining sedimentary layers and renewed deposition

Question 11

In the mid- 1600s, James Ussher determined that Earth was created in 4004 BC based on______ .

A) rates of deposition and erosion of earth materials
B) fossils
C) Biblical passages
D) ancient records from the Egyptians
E) none of the above

Question 12

The principle of inclusions which states that the source of rock fragments found in a unit must be older than the unit with the fragments is important because______ .

A) it allowed geologists to correlate rock units over large distances
B) it provided a tool for sorting out the relative timing of various geologic events
C) it provided a way to recognize if rocks had been deformed
D) it showed that igneous rocks were younger than sedimentary rocks

Question 13

In the late 1800's various principles original horizontality, inclusions, cross cutting relations, etc. arête. were established and used to______ .

A) organize the order in which events occurred on Earth
B) prove that evolution was a valid theory that could explain many geologic observations
C) determine the age of events on Earth
D) determine the age of Earth

Question 14

In the late 1700s James Hutton published his important work entitled______.

A) Principles of Geology
B) Modern Earth Science
C) Theory of the Earth
D) Catastrophism

Question 15

The principle of lateral continuity proposes that sedimentary rock layers continue in all directions until they grade into a different rock type or thin out on the edge of a basin is important because______ .

A) it showed that catastrophism could not explain the flat layers of the earth
B) it allowed geologists to correlate sedimentary rock units over large distances
C) it provided an explanation how rocks behave in a depositional setting
D) it provided a way to recognize if rocks had been deformed

Question 16

The principle of superposition which states that in undeformed rocks, the younger rocks will be on top of older rocks, is particularly important because ______ .

A) it provided an order for assembling the relative ages of various rock layers
B) it showed that the interior of the earth is not growing outward
C) it proved that life evolved by putting fossils in a logical order
D) it supports the laws of gravity which indicate that rocks must be deposited on something that already exists

Question 17

James Hutton stated "We have a chain of facts which clearly demonstrates that the materials of the wasted mountains have traveled through the rivers". He was referring to ______.

A) evidence to support Bishop Ussher's Earth age
B) evidence of the prominence of catastrophic events
C) evidence of the fact that volcanoes have ejected geologic materials
D) evidence Earth having plenty of time for weathering and erosion

Question 18

If you observe a nonconformity, you would infer that the region had experienced ______.

A) uplift and tilting of sedimentary units that exposes them to erosion over a period of time with subsequent renewed deposition
B) intrusion of igneous rocks into a depositional setting, forcing the sedimentary layers upward and possibly deforming them, followed by subsidence of the remaining sedimentary layers and renewed deposition
C) deposition in shallow water, uplift or lowering of sea level enough to expose the rocks to erosion and non- deposition for a period of time, and subsequent resubmergence of the remaining sedimentary units where they experience new deposition
D) deposition of sedimentary layers on crystalline igneous or metamorphic rocks that are exposed at the surface of the earth

Question 19

The principle of horizontality which states that sediments are usually deposited in relatively flat layers is important because______ .

A) it provided an explanation how rocks behave in a depositional setting
B) it showed that catastrophism could not explain the flat layers of the earth
C) it allowed geologists to correlate sedimentary units over large distances
D) it provided a way to recognize if rocks had been deformed

Question 20

A major difference between Catastrophism and Uniformitarianism is______ .

A) catastrophism requires all changes on earth be due to unpredictable events that cannot be explained while Uniformitarianism proposes that all events are predictable
B) catastrophism supports rapid changes on the earth and a young age of Earth while Uniformitarianism requires long times for changes to be significant and thus a very old earth
C) uniformitarianism does not allow for catastrophic events while Catastrophism is based on the assumption that they are the major forces of change in the earth
D) uniformitarianism explains the young age of the earth by suggesting that while processes have not changed over time, the rates of processes may vary significantly

Question 21

You pick up a piece of sandstone. In the rock sample you see an impression of a sea shell in the rock. This type of fossil is a ______ .

A) mold
B) pseudofossil
C) permineralized fossil
D) cast

Question 22

Consider the below diagram of sedimentary layers. We know that the top layer is youngest. Which of the below is not one of the reasons we know this?

A) the principle of inclusions
B) the principle of superposition
C) the principle of original horizontality
D) the principle of lateral continuity

Question 23

Which of the following is not a fossil?

A) a tooth from an early man site in a lake sediment deposit
B) a mummified sloth in a cave
C) imprint of an invertebrate shell in a mudstone
D) None of the above- these are all fossils.

Question 24

You go for a hike across an outcropping of sandstone and you see large footprints in the sandstone. You have just found______ .

A) proof of an ancient flood
B) a mold
C) Bigfoot
D) a trace fossil

Question 25

Which of the following best characterizes an angular unconformity?

A) The discordant boundary between older strata and an intrusive body of granite.
B) Tilted strata that lie below other strata that is also tilted, but at a different angle.
C) Horizontal lava flows lie below the unconformity and horizontal; sedimentary strata lie above.
D) Tilted strata lie below the unconformity; bedding in younger strata above is parallel to the unconformity.

Question 26

Visualize five horizontal undeformed sedimentary strata exposed in a cliff or canyon wall identified by consecutive numbers, with 1 representing the lowest of the five beds and 5 representing the highest of the 5 beds. Which of the following statements concerning the strata is true?

A) Bed 4 is older than bed 2.
B) Bed 5 is the oldest.
C) Beds l and 3 are older than bed 4.
D) Bed 3 is older than beds 2 and 4.

Question 27

Which of the following organisms would be most likely to be preserved in the geologic record?

A) a clam with a thick calcite shell that lived on a mudflat
B) the bones of a dinosaur that lived in a humid environment
C) a tree
D) a mussel that clings to rock outcrops in the surf zone

Question 28

By applying the law of superposition,______ dates can be determined.

A) radiometric
B) conventional
C) relative
D) both relative and radiometric

Question 29

Which of the following geologic observations would not bear directly on working out the sequence of geologic events in an area?

A) a well- exposed dike of basalt in sandstone
B) an unconformity between a granite and sandstone
C) inclusions of sandstone in a granite pluton
D) the feldspar and quartz contents of a granite

Question 30

Petrified wood is an example of a fossil formed by ______.

A) direct preservation
B) permineralization replacing original cellulose of the wood
C) cast and mold preservation
D) trace fossil imprints

Question 31

A worm would stand a poor chance of being fossilized because ______ .

A) worms have been rare during the geologic past
B) worms contain no carbon- 14
C) worms have no hard parts
D) all of these

Question 32

Assume that you have just examined several flat- lying sedimentary layers. After much study you determine that there is a considerable span of time missing between two of the sedimentary rock layers at this site. You have just discovered an_______.

A) disconformity
B) series of conformable strata
C) angular unconformity
D) example of cross- cutting relationships

Question 33

The Morrison Formation is exposed in the western United States and represents a nonmarine deposit with abundant dinosaur fossils. Much of the Morrison is pure mudstone, yet it is common to find highly polished pebbles and cobbles in the mud. Which of the following do you think is the best explanation of these cobbles?

A) They are impossible; people must have put them there.
B) They are gastroliths, a trace fossil.
C) They were placed in the mud by space aliens.
D) They represent meteorites that killed the dinosaurs.

Question 34

A child from down the street from your house brings an object that looks like a bone, and says "look, I found a dinosaur bone." Which of the following would not be useful in evaluating their claim?

A) Examine the object for hardness to determine if the sample is permineralized.
B) Evaluate the object for fine textures indicative of bone material or replaced bone material.
C) Extract charcoal from the object and use carbon- 14 dating.
D) Ask if the object was found embedded in rock.

Question 35

What fundamental concept states that in a horizontal sequence of conformable sedimentary strata, each higher bed is younger than the bed below it?

A) law of original correlation
B) law of superposition
C) theory of superstition
D) theory of correlative deposition

Question 36

Who made the first clear statement of the law of superposition? When?

A) John Stuart Priestly, 19^thcentury
B) William Smith, 18^th century
C) Nicolaus Steno, 17^th century
D) John Wesley Powell, 19^th century

Question 37

Paleontology is the study of______ .

A) prehistoric human history
B) ancient life
C) paleo meaning old, and ontology referring to philosophical study of nature, so paleontology is the study of old nature
D) none of the above

Question 38

One type of fossil that can preserve details of organic soft parts is ______.

A) carbonized imprints
B) coprolites
C) mold
D) cast

Question 39

Rare, but complete preservation of organism occurs in______ .

A) shale
B) amber
C) limestone
D) mudstone

Question 40

______is an erosional contact between tilted, older strata below and horizontal, younger strata above.

A) An angular unconformity
B) Cross cutting
C) A disconformity
D) Inverse bedding

Question 41

Oysters are an invertebrate the lives today in brackish waters along coastal zones. When a geologist working in stratified rocks observes a limestone bed with oyster fossils overlain by beds with clam and echinoderm fossils indicative of marine conditions, the safest conclusion to gather from the fossils is that ______.

A) the oysters evolved into clams and echinoderms
B) the oysters went extinct while these rocks were being deposited
C) the environment changed as sea level rose, displacing the oysters environment with marine conditions represented by the clams and echinoderms
D) There is not sufficient information to reach any conclusion from these observations.

Question 42

What is amber?

A) a prehistoric plant stem
B) permineralized wood
C) hardened tree resin
D) fossilized bone marrow

Question 43

Which of the following is an essential characteristic of an index fossil?

A) The fossils are exceptionally abundant and well preserved.
B) The fossils occur in deep- water marine sediments, but the organism actually lived in the sunlit, surface layer of the ocean.
C) The organism only lived for a short period of geologic time.
D) The organism lived only in specific environments such as beaches or estuaries.

Question 44

Faunal succession recognized in the sequence of fossils in stratified sedimentary rocks was a key concept that led to______ .

A) catastrophism and evidence the world was once covered with water
B) continental drift
C) sea floor spreading
D) the concept of evolution of life on Earth

Question 45

The decay of ⁴⁰K has a half of 1.3 × 10⁹ years. The age of Earth is estimated at 4.6 × 10⁹ years. The decay of ⁴⁰K is a major heat source for Earth's interior. Relative to today, how much more heat was produced by ⁴⁰K in the early Archaeon era or 3.9 × 10⁹ years ago?

A) 6x
B) 8x
C) 4x
D) 2x

Question 46

Assume that man's recorded history can be stretched back to 4600 years before the present. This is approximately what fraction of geologic time?

A) one hundred- thousandth
B) one billionth
C) one millionth
D) one ten- thousandth

Question 47

When a radioactive isotope decays by electron capture, the electron______ .

A) makes the parent isotope into an ion with a charge of negative one
B) combines with a proton in the nucleus; the atomic number of the daughter is one less than the parent
C) combines with a neutron in the nucleus, raising the mass number of the daughter isotope by one
D) makes the daughter isotope into an ion with a charge of positive one

Question 48

When a rock first crystallizes it has unstable isotopes but as of yet no daughter products. After three half- lives, how much total mass has been lost due to decay?

A) two- thirds
B) seven- eighths
C) one- half
D) none

Question 49

Which radioactive decay used for radiometric dating is not an isotope that was generated during nuclear synthesis in the star that went supernova and its products became our solar system?

A) 40_K
B) 147_Sm
C) 238_U
D) 14_C

Question 50

The ______is the idea or concept that ancient life forms succeeded each other in a definite, evolutionary pattern and that the contained assemblage of fossils can determine geologic ages of strata.

A) law of correlative indexing
B) principle of cross correlation
C) principle of fossil succession
D) law of fossil regression

Question 51

Which of the following refers to the investigative process by which geologists identify and match sedimentary strata and other rocks of the same ages in different areas?

A) strata indexing
B) super matching
C) correlation
D) cross- access dating

Question 52

A geologist observes abundant fossils of a distinctive trilobite species in a shale, but this trilobite disappears as she walks through the shale. In younger rocks, just above the horizon where the fossil disappears another species of trilobite becomes the prominent fossil in similar shales. Which conclusion is most logical for this observation?

A) A hurricane or other catastrophe killed all of the early species so the other species could move in.
B) The second, trilobite group in the upper section went extinct where the change in fossils is seen.
C) The first trilobite species went extinct and its ecological niche was occupied by another species, which may have evolved from the first.
D) The organisms whose remains form the first fossil moved from the area for unknown reasons.

Question 53

The ratio of parent to daughter isotopes in a radioactive decay process is 0.40. How many half- lives have elapsed since the material was 100% parent atoms?

A) more than 3
B) less than l
C) between 2 and 3
D) between l and 2

Question 54

The subdivision of the geologic time scale that represents the longest time span is called an______ .

A) period
B) epoch
C) eon
D) era

Question 55

What is the age of Earth accepted by most scientists today?

A) 6.4 billion years
B) 6.4 million years
C) 4.5 billion years
D) 4.5 million years

Question 56

Which of the following describes radioactive decay by beta particle emission?

A) The daughter isotope has an atomic number two less than the parent and a mass number four less.
B) The mass number of the daughter isotope is one more than the parent, and both isotopes have the same atomic number.
C) The atomic number of the daughter isotope is one more than the parent; the mass numbers are the same.
D) The daughter isotope has an atomic number one less than the parent and a mass number two less.

Question 57

You observe a distinct, red sandstone rock body about 50 m thick that is depositionally overlain by a red shale with interbedded gypsum and you follow this boundary in the rock bodies for 1 km until you cross a fault which has displaced the boundary between the two rock bodies. You walk along the fault and see a boundary between a 50 m thick red sandstone and overlying red shale interbedded with gypsum. You conclude______ .

A) the second exposure of sandstone, shale and gypsum correlates to the first, and the boundary between the sandstone and shale is the same stratigraphic horizon
B) this new exposure of sandstone, shale and gypsum must be a different age rock unit
C) the stratigraphic section must have been inverted by the deformation; the rocks are upside down
D) this is impossibly complex; the fault broke up all the rocks

Question 58

Which of the following is not a very long- lived, radioactive isotope?

A) Rb- 87
B) C- 14
C) K- 40
D) U- 238

Question 59

The half- life of carbon- 14 is about 6000 years. Assume that a sample of charcoal formed by burning of living wood 15,000 years ago. How much of the original carbon- 14 would remain today?

A) between one- half and one- fourth
B) more than one- half
C) between one- half and one- third
D) between one- fourth and one- eighth

Question 60

An important absolute dating measure is the decay of ¹⁴⁷Sm to ¹⁴³Nd. What type of radioactive decay is involved in this parent- daughter pair?

A) alpha decay
B) beta decay
C) a positron capture
D) electron capture

Question 61

______dating based on radioactivity are very important for studying Precambrian geologic history because______ in such strata.

A) Absolute; fossils are rare
B) Relative; fossils are rare
C) Relative; fossils are abundant
D) Absolute; fossils are abundant

Question 62

Examine the words and/or phrases below and determine the relationship among the majority of words/phrases. Choose the option that does not fit the pattern.

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

Question 63

As it relates to the names of the eras in the geologic time scale, what is meant by "zoic"?

A) places; geographic references
B) time; recording of events
C) life; living things
D) rocks; lithified strata

Question 64

Examine the words and/or phrases below and determine the relationship among the majority of words/phrases. Choose the option that does not fit the pattern.

A) superposition
B) inclusions
C) correlation
D) original horizontality

Question 65

The era known as the "age of mammals" is the______ era.

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

Question 66

The percentage of radioactive atoms that decay during one half- life is______ .

A) 50
B) 25
C) 75
D) 100

Question 67

The radioactive isotope, K- 40, has ______ as a daughter product.

A) Ar- 38
B) K- 38
C) Ar- 40
D) K- 39

Question 68

Examine the words and/or phrases below and determine the relationship among the majority of words/phrases. Choose the option that does not fit the pattern.

A) delta capture
B) alpha emission
C) electron capture
D) beta emission

Question 69

There is geologic evidence that Earth has experienced______ .

A) many episodes of mountain building but not much erosion
B) many episodes of both mountain building and erosion
C) few episodes of erosion and an unknown amount of mountain building
D) only a few recent episodes of mountain building but much erosion

Question 70

Strata above an______were deposited after older strata were deformed.

A) conformity
B) nonconformity
C) disconformity
D) angular unconformity

Question 71

Which of the following denotes the divisions of the geologic time scale in correct order of decreasing lengths of time beginning with the longest time interval and ending with the shortest?

A) eon, era, period, epoch
B) eon, epoch, period, era
C) era, period, epoch, eon
D) eon, era, epoch, period

Question 72

After three half- lives,______ of an original radioactive parent isotope remains.

A) 1/3
B) 1/5
C) 1/7
D) 1/2

Question 73

In the last few years improvements in technology have allowed geologists to date single grains of some minerals in rocks. A geologist separates 5 grains of the mineral zircon, which can be dated by the Uranium- lead method, and the crystal retains parent and daughter through weathering, erosion, and deposition. Thus, dating each mineral grain only gives the age of the source rock that was eroded, to produce that sand, from which the zircon grain is derived. The 5 grains yield ages of 160, 110, 2020, 66, and 162 million years. What do these ages tell you about the age of the sedimentary strata?

A) They are younger than 66 million years.
B) There are no age constraints from this data; sedimentary rocks cannot be dated by geochronology.
C) They are between 160 and 162 million years.
D) They are Precambrian rocks, older than 2020 million years.

Question 74

An unconformity involving older metamorphic rocks and younger sedimentary strata is termed a ______.

A) disconformity
B) angular unconformity
C) nonconformity
D) conformity

Question 75

Different periods of the geologic time scale are different in length. Why?

A) The geologists who developed the time scale did not care about absolute ages.
B) The time scale was developed ad hoc, as a relative time scale based on rocks and fossil succession with no reference to absolute time when it was developed.
C) Early geologists made mistakes, but it was easier to retain the terminology in the time scale.
D) None of the above.

Question 76

About 88 percent of geologic time is represented by the time span called the______ era.

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

Question 77

Radiometric data was ______modern geology replacing catastrophism.

A) the key to
B) counter evidence for
C) the only reason for
D) relatively unimportant in

Question 78

When a beta particle is emitted, the mass number of the isotope______.

A) remains unchanged
B) goes up one
C) goes down two
D) goes down four

Question 79

The era of "ancient life" is the______ era.

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

Question 80

An______ is an erosional unconformity with parallel beds or strata above and below.

A) nonconformity
B) conformity
C) disconformity
D) angular unconformity