Deck 4: Geologic Time: a Story in the Rocks

Question 1

__________ are atoms of the same element that have the same number of protons but different numbers of neutrons.

Answer 1

Isotopes

Question 2

The principle of __________ states that most sediment is deposited as nearly horizontal beds.

A) superposition
B) original horizontality
C) limited horizontality
D) faunal succession

Answer 2

B

Question 3

The thin, sooty iridium-rich layer found at the end of the Permian is an example of a __________ __________.

Answer 3

key bed

Question 4

Dinosaurs evolved during the __________ Era.

Question 5

The principle of __________ __________ states that species succeeded one another through time in a definite and recognizable order.

Question 6

According to the principle of __________, a rock must first exist before anything can happen to it.

A) superposition
B) original horizontality
C) crosscutting relationships
D) evolution

Question 7

In order to determine the absolute ages of rocks, __________ __________ relies on measuring the relative amounts of parent and daughter isotopes.

Question 8

A/an __________ is an unconformity in which the sedimentary layers above and below the unconformity are parallel.

Question 9

The biggest mass extinction in Earth's history occurred at the end of the __________ Period.

A) Ordovician
B) Permian
C) Cretaceous
D) Tertiary

Question 10

During a __________ __________, many life-forms on Earth die out suddenly.

Question 11

The fact that sedimentary rocks usually become younger from bottom to top is the principle of __________.

Question 12

Matching rocks of similar ages from different localities is __________.

Question 13

The volcanic gas __________ forms small particles called aerosols that reflect sunlight and cool Earth.

A) carbon monoxide
B) oxygen
C) nitrogen
D) sulfur dioxide

Question 14

The __________ encompasses approximately the first 4 billion years of Earth's history.

Question 15

__________ __________ refers to time measured in years.

Question 16

Measurement of __________ age refers only to the order in which events occurred.

A) relative
B) absolute
C) radiometric
D) Phanerozoic

Question 17

__________ __________ come from organisms that are abundantly preserved in rocks and are useful for dating.

Question 18

Volcanic eruptions eject __________ __________ into the atmosphere, a greenhouse gas that can cause warming.

Question 19

A basalt dike cutting older sedimentary rocks is an example of the principle of __________ __________.

Question 20

__________ __________ refers to the order in which geologic events occurred.

Question 21

Geologists establish the age relationship of rocks from different locations through the process of __________.

A) conformation
B) invention
C) information
D) correlation

Question 22

Layers of sedimentary rock are __________ if they were deposited without detectable interruption.

A) conformable
B) disconformable
C) unconformable
D) nonconformable

Question 23

To be useful, an index fossil is produced by an organism that:

A) is not well preserved.
B) existed for a relatively short time.
C) existed for a very long time.
D) lived in one place only.

Question 24

Relative age measurement refers to:

A) age measured in years.
B) the order in which events occur.
C) age measured only by carbon-14 dating.
D) age measured only by potassium-argon dating.

Question 25

In a disconformity:

A) the sedimentary layers above and below the unconformity are parallel.
B) the sedimentary layers below the unconformity are tilted.
C) sedimentary rocks lie on older metamorphic rocks.
D) sedimentary rocks lie on older igneous rocks.

Question 26

Imagine that you found two sandstone beds about 200 kilometers apart. The rock in one region was similar to the rock in the other, but one bed was several million years older than the other. From this information, you would conclude that:

A) the two beds were time correlated.
B) both beds would contain the same index fossils.
C) the two beds were lithologically correlated.
D) a and b

Question 27

A magmatic intrusion cutting through sedimentary layers:

A) must be younger than these sedimentary layers.
B) must be older than these sedimentary layers.
C) is of exactly the same age as these sedimentary layers.
D) cannot be used for any relative age measurements.

Question 28

Precambrian refers to all the time before the start of the __________ Eon.

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

Question 29

The half-life of potassium-40 is 1.3 billion years. If a rock that formed 2.6 billion years ago originally contained 5 grams of potassium-40, about __________ grams of potassium-40 would be left in that rock today.

A) 0.0125
B) 0.125
C) 1.25
D) 0.25

Question 30

Geologic evidence for the cause of the extinction event at the end of the Cretaceous includes:

A) a silicate-rich layer.
B) glacier deposits.
C) iron-nickel deposits.
D) an iridium-rich layer.

Question 31

In a __________, the sedimentary layers above and below the unconformity are parallel.

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

Question 32

Scientists have noted that mass extinctions have coincided with:

A) unusually high rates of volcanic activity.
B) meteorite impacts.
C) slow step-wise evolution.
D) a and b

Question 33

Fish, amphibians, and reptiles all evolved during the __________ Era/Eon.

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

Question 34

An unconformity in which tectonic activity tilted older sedimentary rock layers before younger sediment accumulated is:

A) an angular unconformity.
B) a disconformity.
C) conformable.
D) a nonconformity.

Question 35

The principle of faunal succession states that:

A) sediment usually accumulates in horizontal layers.
B) sedimentary rocks generally become younger from bottom to top.
C) fossil organisms succeeded one another through time in a definite and recognizable order.
D) rocks can be dated by studying radioactive decay of the elements.

Question 36

The earliest fossils have been found from the __________ Eon.

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

Question 37

Scientists have determined the Earth's age to be about __________ years.

A) 65 million
B) 248 million
C) 543 million
D) 4.6 billion

Question 38

The principle of original horizontality is based on the fact that:

A) sediment usually accumulates in horizontal layers.
B) sedimentary rocks generally become younger from bottom to top.
C) sedimentary rocks must be older than an intruding dike.
D) rocks can be dated by studying radioactive decay of the elements.

Question 39

Humans evolved during the __________ Era/Eon.

A) Cenozoic
B) Proterozoic
C) Paleozoic
D) Mesozoic
Multiple Choice

Question 40

The smallest unit of geologic time is a/an __________.

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

Question 41

In a disconformity, older sedimentary beds were tilted and eroded before younger layers were deposited.

Question 42

Carbon-14 dating is used to determine the age of materials older than 50,000 years.

Question 43

Parent and daughter isotopes occur when an isotope is __________.

A) stable
B) unstable
C) radioactive
D) b and c

Question 44

The half-life of a radioactive isotope is:

A) the time it takes for half the atoms of the radioactive isotope in one sample to decay.
B) half of one radioactive atom.
C) the time it takes for all atoms of the radioactive isotope in one sample to decay.
D) the electron of one radioactive atom.

Question 45

The Permian extinction occurred at the end of the:

A) Paleozoic Era.
B) Mesozoic Era.
C) Cenozoic Era.
D) Proterozoic Eon.

Question 46

The largest time units in the geologic column are periods.

Question 47

The longer the time span that a species existed, the more precisely an index fossil can be used to determine the age of a rock.

Question 48

When a parent isotope decomposes, the quantity of daughter isotopes in a sample decreases with time.

Question 49

Volcanic eruptions can influence the climate both by cooling as well as by warming the atmosphere.

Question 50

Dinosaurs roamed the Earth during the:

A) Paleozoic Era.
B) Mesozoic Era.
C) Cenozoic Era.
D) Proterozoic Eon.
True/False

Question 51

Relative age measurement provides scientists with age measured in years.

Question 52

Many scientists believe that a giant meteorite impact caused the extinction of the dinosaurs.

Question 53

Humans evolved and lived wholly during the Mesozoic Era.

Question 54

Isotopes with long half-lives give good ages for old rocks, but not enough daughter isotopes accumulate in young rocks for good age measurement.

Question 55

The principle of crosscutting relationships states that fossil organisms succeeded one another through time in a definite and recognizable order and that the relative ages of rocks can therefore be recognized from their fossils.

Question 56

The principle of superposition assures us that sedimentary rocks formed continuously from 2 billion to 200 million years ago.

Question 57

Phanerozoic Eon sedimentary rocks contain only microscopic fossils of single-celled organisms.

Question 58

Geologists use radioactive elements in rocks mainly to identify:

A) their relative age.
B) an angular disconformity.
C) a nonconformity.
D) their absolute age.

Question 59

Younger layers of sediment always accumulate on top of older layers.

Question 60

Fossil remains first became very abundant during the Cambrian Period.