Deck 4: Geologic Time Concepts and Principles

Question 1

Some scientists have suggested that human intervention in the Earth system has been responsible for a new epoch of geologic time called the Anthropocene.

Answer 1

True

Question 2

Evaporites in the rock record commonly indicate a period of arid climate.

Answer 2

True

Question 3

Divisions of the geologic time scale are divided into equal increments of 250 million years.

Answer 3

False

Question 4

James Hutton is considered the founder of modern day geology.

Question 5

C arbon-14 dating technique is generally used to date living matter .

Question 6

If sedimentary rocks are tilted steeply, they most likely have experienced an episode of deformation.

Question 7

The sentence "The Paleozoic Era occurred before the Mesozoic Era" is an example of absolute dating.

Question 8

Relative dating of geologic events was not possible before the discovery of radioactivity in the late 19th century.

Question 9

Relative dating approximates how long ago a particular event took place .

Question 10

Geologists use the natural radioactive decay of elements as the foundation for relative time dating.

Question 11

Atoms with an unequal number of protons and neutrons are called isotopes.

Question 12

Obtaining an absolute age for most sedimentary rocks is difficult.

Question 13

We are currently in the Quaternary period of the Cenozoic era.

Question 14

At times in Earth's history, volcanoes have been more active and large ice sheets have covered the continents. The fact that this is not observed today contradicts uniformitarianism.

Question 15

The present geologic time scale is based on relative and numerical dating techniques.

Question 16

Protons are neutral particles in the nucleus of an atom.

Question 17

The principle of lateral continuity states that sedimentary beds are deposited horizontally with the oldest beds on the bottom.

Question 18

Tree-ring dating, or dendrochronology, is a relative dating method.

Question 19

Nicolas Steno used a mathematical model and the rate of Earth's cooling to calculate that the age of the Earth must be 20-400 million years old.

Question 20

All atoms of the same element have the same atomic number.

Question 21

Any time an element undergoes radioactive decay, it becomes a new element.

Question 22

Who developed the principle of uniformitarianism?

A) James  Hutton
B) William Smith
C) Charles  Darwin
D) Abraham  Werner
E) Alfred  Wegener

Question 23

The time necessary for one-half of the original number of radioactive atoms of an element to decay to a stable daughter product is known as a(n) ____.

A) scale
B) metamorphosis
C) half-life
D) alpha decay
E) relative age

Question 24

Radiometric dates are unaffected by metamorphism.

Question 25

A rock sample containing an isotope with a half-life of 28 million years has an initial mass of 184 grams. How much time has elapsed after three half-lives?

A) 6.5 million years
B) 9.3 million years
C) 32 million years
D) 56 million years
E) 84 million years

Question 26

After three half-lives, a radioactive element will have ____ of its original parent atoms.

A) 1/2
B) 1/6
C) 1/3
D) 1/8
E) 1/32

Question 27

A rock sample containing an isotope with a half-life of 28 million years has an initial mass of 184 grams. How much parent isotope remains after 3 half-lives?

A) 23 grams
B) 46 grams
C) 69 grams
D) 115 grams
E) 161 grams

Question 28

What theory proposes that the same processes seen today have operated throughout geologic time (i.e. the present is the key to the past)?

A) conformitarianism
B) inclusion
C) fossil succession
D) uniformitarianism
E) evolution

Question 29

You are hiking in the mountains and come across a cliff in which a vein of igneous rock is cutting across the layers of sedimentary rock in the area. The igneous rock is ____ than the sedimentary rock.

A) younger
B) older
C) thicker
D) thinner
E) dipping more steeply

Question 30

The principle of superposition states that ____.

A) older rock layers are found above younger rock layers
B) younger rock layers are found above older rock layers
C) younger rock layers are found below older rock layers
D) ages of rock layers can't be determined without fossil evidence
E) rock layers with similar lithologies are likely the same age

Question 31

The principle of fossil succession is one of the principles for relative-age determinations of strata and their contained fossils.

Question 32

Atoms of the same element with different numbers of neutrons in the nuclei are known as ____.

A) ions
B) electrons
C) isotopes
D) neutrons
E) nucleotides

Question 33

Lord Kelvin calculated Earth was 20-400 million years old. Why was he wrong?

A) He didn't account for the erosion of sediments.
B) He didn't account for the presence of salt deposits.
C) He wrongly assumed the oceans were initially fresh.
D) His thermometer was incorrectly calibrated.
E) He didn't know Earth had an internal heat source.

Question 34

James Hutton pioneered the principle that we know today as uniformitarianism.

Question 35

A rock sample containing an isotope with a half-life of 28 million years has an initial mass of 184 grams. How much daughter isotope is present after three half-lives?

A) 23 grams
B) 46 grams
C) 69 grams
D) 115 grams
E) 161 grams

Question 36

In the early 20th century, Pierre and Marie Curie discovered that radioactive decay produces heat.

Question 37

The half-life of carbon 14 is ____ years.

A) 5,730
B) 40,110
C) 80,220
D) 280,770
E) 561,540

Question 38

Determining specific, quantitative dates for rock units or events expressed in years before the present is known as ____ dating.

A) relative
B) absolute
C) sedimentary
D) correlative
E) blind

Question 39

Because heat and pressure affect the ratio of radioactive parent to stable daughter, ____ rocks generally are difficult to date accurately by radiometric dating.

A) igneous
B) sedimentary
C) metamorphic
D) mafic
E) felsic

Question 40

The ____ states that sediment extends laterally in all directions until it thins and pinches out, or terminates, against the edge of the depositional basin.

A) principle of original horizontality
B) principle of superposition
C) principle of lateral continuity
D) principle of cross-cutting relationships
E) principle of uniformitarianism

Question 41

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

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

Question 42

A(n) ____________________ is a break in the geologic record resulting, at times, from erosion.

Question 43

Placing geologic events in a chronological order from their position in the rock record is called ____.

A) positioning
B) sequencing
C) relative dating
D) absolute dating
E) numerical dating

Question 44

The emission of an electron from the nucleus is called ____________________.

Question 45

The principle of ____________________ states that rock layers extend out in all directions until they pinch out or terminate against the edge of a basin.

Question 46

A division on the geologic time scale represents ____.

A) the passage of 500,000 years.
B) the passage of 250 million years
C) an increase in reptilian poopulation by 100,000
D) an increase in population of all living organisms by one million
E) a distinctive event in the rock record

Question 47

Which scientist used a mathematical model and the rate of Earth's cooling to calculate that the age of the Earth must be 20-400 million years old?

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

Question 48

Lead-214 (Pb-214) that undergoes beta decay becomes ____.

A) Pb-212
B) Bi-210
C) Bi-214
D) Tl-214
E) Tl-210

Question 49

__________________, an isotope commonly used to date organic material, is formed from the conversion of nitrogen-14 by cosmic rays.

Question 50

Atoms of a particular element that have a different number of neutrons in their nuclei are called ____________________.

Question 51

The principle of _________________________ states that an igneous intrusion or a fault must be younger than the rock it intrudes or displaces.

Question 52

Uranium-238 (U-238) that undergoes alpha decay becomes ____.

A) Th-232
B) Th-234
C) Pa-234
D) Pu-242
E) U-234

Question 53

If sedimentary rocks are tilted steeply, we assume that they were initially deposited ____________________.

Question 54

The two types of geologic age dates are ____________________ and ____________________.

Question 55

The principle of ____________________ states that, in a sequence of sedimentary rocks, those found at the bottom of the sequence are oldest.

Question 56

Radiometric dating is based on ____.

A) the presence of fossils
B) cross-cutting relationships
C) spontaneous decay of radioactive elements
D) superposition
E) dendrochronology

Question 57

Uniformitarianism is the assumption that ____.

A) principles of one branch of science apply to other branches of science
B) catastrophic events don't impact Earth processes
C) younger sedimentary rocks are at the top of rock sequences
D) current rates of atmospheric warming are unsustainable
E) present-day geological processes also occurred in the past

Question 58

The most notable trace in the geologic record of human activities is likely to be a(n) ____.

A) more diverse pollen record
B) concrete and metal debris field left from cities
C) expansion of farmland
D) increase in carbon dioxide levels, as recorded by ice cores
E) more alkaline ocean

Question 59

Assigning a specific date to a rock, which is measured in years before present, is known as ____.

A) relative dating
B) absolute dating
C) superposition
D) carbon dating
E) fossil succession

Question 60

The most accurate radiometric dates are obtained from ____________________ rocks.

Question 61

Discuss the recent proposal by Paul Crutzen and Eugene Stoermer for the addition of the Anthropocene Epoch to the Geologic Time Scale. What evidence supports this inclusion? What refutes it?

Question 62

List three ways in which scientists can detect changes in climate, particularly due to the accumulation of carbon dioxide, by examining the geologic record.

Question 63

Explain how John Wesley Powell could have used the relative dating principles of original horizontality, superposition, and lateral continuity on his journey through the Grand Canyon.

Question 64

Discuss the historic use of relative and absolute dating to develop the geologic time scale. Were relative dates or absolute dates first employed to develop this time scale? Explain your reasoning.

Question 65

List at least three pieces of information you would need when attempting to radiometrically date an igneous rock using uranium-238/lead-206 isotopes.

Question 66

Discuss methods of absolute dating that may provide insight into relatively recent climate change. How are these methods employed?

Question 67

Describe and discuss the methods for deriving absolute geologic dates. How have these methods influenced the geologic time scale? Discuss possible sources of uncertainty in dates determined using these methods.

Question 68

Geologists prefer to use rocks from closed systems when they radiometrically date the rocks. What is a closed system, and why is it important for radiometric dating?

Question 69

Compare and contrast the attempts by James Ussher and Lord Kelvin to measure the age of Earth. Explain what they did and why it was or was not scientific.

Question 70

Early geologists tried calculating the age of Earth based on sedimentation rates and deduced ages of 1 million to 2 billion years old. Explain the logic behind using sedimentation rates to calculate the age of Earth, and explain at least two reasons why this method did not work.