Deck 17: Geologic Time: Concepts and Principles

Question 1

A clast of granite found in a conglomerate is determined to be one hundred million years old. What does this information suggest about the conglomerate?

A)The conglomerate is older than 100 million years.
B)The conglomerate is younger than 100 million years.
C)The conglomerate was exposed to volcanic processes 100 million years ago.
D)The conglomerate experienced volcanic processes more than 100 million years ago.
E)We cannot determine anything about the age of the conglomerate from this information.

Answer 1

The conglomerate is younger than 100 million years.

Question 2

The principle of lateral continuity says that if a fault occurs in a sequence of sedimentary rocks, the fault is older than the rocks.

Answer 2

False

Question 3

Radiocarbon dating is only useful for organic material.

Answer 3

True

Question 4

A fossil is determined to be 175,000 years old. This is an example of a(n)____ date.

A)radiometric
B)certain
C)relative
D)sequential
E)inferential

Question 5

A hiatus between igneous or metamorphic rocks and sedimentary rocks is represented in the rock record by a(n)____.

A)angular unconformity
B)hiatal unconformity
C)nonconformity
D)anticonformity
E)disconformity

Question 6

What is the general term for a gap in the geologic rock record that represents a period of non-deposition, erosion, or both?

A)nonconformity
B)disconformity
C)angular unconformity
D)anticonformity
E)unconformity

Question 7

What is the approximate age of Earth?

A)10,000 years
B)12.6 million years
C)3.2 million years
D)4.6 billion years
E)13.5 billion years

Question 8

The geologic time scale is a static concept that has allowed geologists to accurately date past events.

Question 9

Geologists are correlating past geologic events to see if there are correlations with climate changes.

Question 10

What principle states that in an undisturbed succession of sedimentary rocks, the oldest layer is at the bottom and the youngest is at the top?

A)The principle of cross-cutting relationships
B)The principle of inclusions
C)The principle of fossil succession
D)The principle of uniformitarianism
E)The principle of superposition

Question 11

Fossils cannot usually be dated directly because they are not composed of minerals that naturally contain radioactive isotopes.

Question 12

To correlate rock units over a large area or to correlate age-equivalent units of different composition, fossils and the principle of fossil succession must be used.

Question 13

Geologic time periods are uniformly divided into increments of five million years.

Question 14

Lithostratigraphic units are defined by the physical attributes of the rocks

Question 15

Uniformitarianism is the assumption that ____.

A)principles of one branch of science apply to other branches of science
B)catastrophic events do not impact Earth processes
C)younger sedimentary rocks are always found at the top of a horizontal rock sequence
D)present day warming of the atmosphere is unsustainable
E)present day geologic processes also occurred in the past

Question 16

The placement of events in a sequential order based upon their position in the rock record is referred to as ____ dating.

A)radiometric
B)absolute
C)relative
D)sequential
E)inferential

Question 17

Which statement about methods of determining Earth's age is false?

A)James Ussher derived an age of approximately 6,000 years based on Biblical genealogy.
B)John Joly calculated an age of 90 million years based on how long it would take the oceans to become salty.
C)Lord Kelvin determined an age of 75,000 years by assuming Earth had cooled from a molten state.
D)Early scientists tried to calculate ages based on sedimentation rates.
E)James Hutton calculated the age of Earth by measuring the rate of igneous rock formation.

Question 18

Whose work was the basis for the principle of uniformitarianism and the unavoidable necessity of a great age for Earth?

A)Charles Lyell
B)William Smith
C)James Hutton
D)Lord Kelvin
E)John Joly

Question 19

Stratigraphy is the study of the composition, origin, areal distribution and age relationships of layered rocks.

Question 20

The most visible signs of human activities, such as cities, factories, and power plants, will not be strongly recorded in the rock record.

Question 21

Radiometric dating is possible because ____.

A)daughter isotopes are lost
B)decay constants do not change
C)experimental and sample error is negligible
D)parent isotopes are gained
E)metamorphic and igneous rocks are made of crystals

Question 22

Suppose an isotope has a half-life of 50 million years, and 1\8 of the sample remaining consists of that isotope. What is the age of the rock from which it was taken?

A)150 million years
B)300 million years
C)400 million years
D)600 million years
E)800 million years

Question 23

A half-life is the amount of time required ____.

A)to lose one-half of the daughter isotopes
B)for the mass of a sample to decrease by half
C)for one-half of the parent isotopes to decay to daughter isotopes
D)to gain one-half of the parent isotopes
E)to accurately date a rock sample

Question 24

What is the loss of two protons and two neutrons from the nucleus called?

A)alpha decay
B)beta decay
C)electron decay
D)electron capture
E)half-life decay

Question 25

When an atom of Uranium-238 undergoes alpha decay, it becomes ____.

A)U-234
B)U-236
C)Th-234
D)Th-236
E)Th-238

Question 26

Rock units can be correlated best by examining ____.

A)fossil data, rock types, and key beds
B)the presence of oil, rock sequence, and key beds
C)rock type, rock sequence, and the current environment
D)key beds, rock type, and the current environment
E)fossil data, rock type, and the presence of oil

Question 27

A hiatus between igneous or metamorphic rocks and sedimentary rocks is represented in the rock record by a(n)____.

A)angular unconformity
B)hiatal unconformity
C)nonconformity
D)anticonformity
E)disconformity

Question 28

A rock sample containing an isotope with a half-life of 12 million years has an initial mass of 72 grams. How much of the parent isotope will be present after three half-lives?

A)4.5 grams
B)9 grams
C)18 grams
D)54 grams
E)63 grams

Question 29

When an atom undergoes alpha or beta decay, it ____.

A)becomes an ion of the same element
B)becomes an isotope oh the same element
C)becomes a completely different element
D)may or may not become a completely different element
E)becomes permanently stable

Question 30

What is the maximum age limit for radiocarbon dating of fossils?

A)70,000 years
B)700,000 years
C)7 million years
D)70 million years
E)700 million years

Question 31

Index, or guide, fossils are most useful because they ____.

A)occur over small geographic region
B)lived during a brief period of geologic time
C)rarely occur
D)lived over a long period of geologic time
E)are found in all types of rock

Question 32

The longest divisions of geologic time are called ____.

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

Question 33

A rock sample containing an isotope with a half-life of 12 million years has an initial mass of 72 grams. How much of the daughter isotope will be present after three half-lives?

A)4.5 grams
B)9 grams
C)18 grams
D)54 grams
E)63 grams

Question 34

____ are a type of lithostratigraphic unit with distinctive upper and lower boundaries.

A)Biozones
B)Stratotypes
C)Formations
D)Systems
E)Zones

Question 35

The most useful method for dating the oldest events on Earth is ____.

A)tree ring records
B)radiometric dating of rocks and fossils
C)oxygen isotope ratios from ice cores
D)plankton and isotopes in ocean sediments
E)glacial evidence

Question 36

____ is the study of the composition, origin, areal distribution, and age relationships of layered rocks.

A)Stratigraphy
B)Uniformitarianism
C)Lithography
D)Chronography
E)Biostratification

Question 37

The geologic time scale was initially put together by ____.

A)radiometric dating and correlation
B)superposition, fossil succession and correlation
C)lithostratigraphy and biostratigraphy
D)carbon-14 age dating and lithostratigraphy
E)geologists in the United States

Question 38

Divisions in geologic time represent ____.

A)the passage of 10 million years
B)a mass extinction
C)distinct changes in the rock record
D)the onset of Ice Ages
E)the passage of 20 million years

Question 39

Which principle states that fossil assemblages succeed one another through time in a regular and predictable order?

A)The principle of cross-cutting relationships
B)The principle of inclusions
C)The principle of fossil succession
D)The principle of uniformitarianism
E)The principle of superposition

Question 40

Radiocarbon dating is possible primarily because ____.

A)the ratio of carbon-14 to carbon-12 in the atmosphere is constant
B)carbon-14 is constantly being formed in the upper atmosphere
C)living organisms selectively use carbon-13 and carbon-12
D)organisms stop accumulating carbon-14 when they die
E)carbon 14 decays to oxygen

Question 41

What is the principle of uniformitarianism? Why does the principle of uniformitarianism lead to the conclusion that Earth's age is great?

Question 42

An interval of geologic time not represented by strata in a particular area is a(n)____________________.

Question 43

An examination of fossilized plants and organisms, along with an analysis of rock type enables scientists to reconstruct historical ____________________.

Question 44

What lines of evidence would indicate that a granitic magma body once intruded into a layer of sandstone?

Question 45

____________________ dating is used to obtain absolute age dates.

Question 46

How does relative dating differ from absolute dating?

Question 47

Why don't the sources of uncertainty in radiometric dating invalidate or lend suspicion to the results obtained?

Question 48

In the accompanying figure, what type of feature is represented by the letter U? How did it form?

Question 49

Scientists have coined the ____________________ Epoch to describe present day geologic time and recognize the impact humans have on planet Earth.

Question 50

To determine the age of sedimentary rocks containing fossils, ____________________ zones are established, plotting the overlapping geologic ranges of different species of fossils.

Question 51

Why was Lord Kelvin's argument for the age of Earth fundamentally in error?

Question 52

Different varieties of an atom that have a different number of neutrons in their nuclei are ____________________.

Question 53

The most accurate radiometric dates are obtained from ____________________ rocks. Only in very unusual circumstances can ____________________ rocks be radiometrically dated.

Question 54

What is the goal of the subsurface correlation techniques that are used in the search for oil and gas?

Question 55

The principle of ____________________ states that rock layers extend laterally in all directions unless or until they terminate in one of a number of natural means.

Question 56

A body of strata recognized only on the basis of its fossil content is called a(n)____________________ unit.

Question 57

The geologic time scale was initially developed by using ____________________ dating and subsequently refined by using ____________________ dating.

Question 58

Consider the accompanying figure and place the lettered events in order. Which principles of relative dating did you use and how did you use them? Youngest ____ ____ ____ ____ ____ ____ ____ ____ ____ Oldest