Geologic time/Dating

Question 1

What is a half-life?

Answer 1

A half-life is the amount of time it takes half of the parents(unstable) to become daughters(stable).

Question 2

What are the three types of unconformities called?

Answer 2

Disconformity, nonconformity, and angular unconformity.

Question 3

What is an angular unconformity?

Answer 3

An angular conformity is when horizontal rocks are deformed, and then more rock builds on top of it.

Question 4

What is a disconformity?

Answer 4

A disconformity is when the top rock layer gets eroded, and then more rock builds on top of it

Question 5

What is a nonconformity?

Answer 5

A nonconformity occurs when sedimentary rock gets eroded to expose metamorphic or igneous rock, and then new rock develops on top of it.

Question 6

How does C-14 work?

Answer 6

C-14 is used to date fossils. Scientists compare C-14 and C-12 in a bone. However, correction curves are needed due to changes in the atmosphere that can effect C-14 concentrate.

Question 7

How do you use a varve sequence to date a rock?

Answer 7

A varve sequence is a core found in glacial lakes. There is a layer of mud representing winter and a layer of sand representing summer. Using those layers, you can determine a rocks age, if it is recent.

Question 8

What is alpha decay?

Answer 8

Alpha decay is when 2 protons and 2 neutrons are released as alpha particles.

Question 9

What is beta decay?

Answer 9

Beta decay is when a neutron releases it’s electron and becomes a proton.

Question 10

Name the eons in descending age?

Answer 10

Hadean, archean, proterozoic, phanerozoic.

HAPP(Y)

Question 11

What does hadean mean?

Answer 11

It means molten

Question 12

What is special about the archean eon?

Answer 12

The oldest rock is found then, the ocean and atmosphere developed.

Question 13

What does proterozoic mean?

Answer 13

Early life

Question 14

Name the eras in descending age

Answer 14

Precambrian, paleozoic, mesozoic, cenozoic

Question 15

What does paleozoic mean?

Answer 15

Old life

Question 16

What does mesozoic mean?

Answer 16

Middle life

Question 17

What does cenozoic mean?

Answer 17

Recent life

Question 18

What is the mnemonic device for the periods?

Answer 18

Come Over Some Day, Maybe Play Poker, Three Jacks Kill Two Queens.

Question 19

Name the periods in descending age

Answer 19

Cambrian, ordovician, silurian, devonian, mississippian, pennsylvanian, permian, triassic, jurassic, cretaceous, tertiary (paleogene and neogene), quaternary

Question 20

Name the epochs in descending age

Answer 20

Paleocene, eocene, oligocene, miocene, pliocene, pleistocene, holocene.

Question 21

What is the mnemonic device for the epochs

Answer 21

Pretty Eager Old Men Play Poker Hard (PEOMPPH)

Question 22

What period(s) is the age of invertebrates?

Answer 22

Cambrian and Ordovician

Question 23

What period(s) is the age of fish?

Answer 23

Silurian and Devonian

Question 24

What periods are the age of amphibians?

Answer 24

Carboniferous and Permian

Question 25

What periods are the age of reptiles?

Answer 25

Triassic, Jurassic, and Cretaceous (Mesozoic era)

Question 26

What periods are the age of mammals?

Answer 26

Tertiary, Quaternary (Cenozoic era)

Question 27

When did the ice age cycles start?

Answer 27

2.6 million years ago

Question 28

When was there a meteor impact(dinosaurs died)?

Answer 28

66 million years ago

Question 29

When did pangaea form?

Answer 29

252 million years ago

Question 30

When was the explosion of life?

Answer 30

541 million years ago

Question 31

When did Earth form?

Answer 31

4.6 billion years ago

Question 32

How does the geologic time scale break down?

Answer 32

Eon-era-period-epoch

Question 33

What are the relative age dating rules?

Answer 33

Original horizontality, superposition, lateral continuity, cross-cutting relationships, inclusions, faunal succession

Question 34

What is faunal succession?

Answer 34

Using index fossils to relatively date rocks.

Question 35

What is the rule of inclusions?

Answer 35

Inclusions are older than the rock that contains them.

Question 36

What are cross-cutting relationships?

Answer 36

The intrusion is younger than the rock they intrude.

Question 37

What is lateral continuity?

Answer 37

Sedimentary layers continue horizontally over a distance.

Question 38

What is superposition?

Answer 38

The oldest sedimentary layers are on the bottom.

Question 39

What is original horizontality?

Answer 39

Sedimentary layers form horizontally. Any deformations happen after the rock forms.

Question 40

What is the difference between relative and absolute age dating?

Answer 40

In relative age dating, you establish a series of events to figure out age compared to other rocks. In absolute age dating, you figure a numerical value for the rock's age. You cannot absolutely date sedimentary rocks.

Question 41

How do you figure out how many half-lives have passed?

Answer 41

You use the ratio of parent to daughter and use the fact that the parent decreases by 50% every time.

Question 42

How do you figure out the age of a rock using half-lives?

Answer 42

Once you know how many half-lives have passed in an isotope, you have to multiply that by the half-life time of that isotope.