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ES Finals > Geologic time/Dating > Flashcards

Geologic time/Dating Flashcards

1
Q

What is a half-life?

A

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

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2
Q

What are the three types of unconformities called?

A

Disconformity, nonconformity, and angular unconformity.

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3
Q

What is an angular unconformity?

A

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

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4
Q

What is a disconformity?

A

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

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5
Q

What is a nonconformity?

A

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

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6
Q

How does C-14 work?

A

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.

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7
Q

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

A

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.

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8
Q

What is alpha decay?

A

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

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9
Q

What is beta decay?

A

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

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10
Q

Name the eons in descending age?

A

Hadean, archean, proterozoic, phanerozoic.

HAPP(Y)

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11
Q

What does hadean mean?

A

It means molten

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12
Q

What is special about the archean eon?

A

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

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13
Q

What does proterozoic mean?

A

Early life

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14
Q

Name the eras in descending age

A

Precambrian, paleozoic, mesozoic, cenozoic

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15
Q

What does paleozoic mean?

A

Old life

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16
Q

What does mesozoic mean?

A

Middle life

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17
Q

What does cenozoic mean?

A

Recent life

18
Q

What is the mnemonic device for the periods?

A

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

19
Q

Name the periods in descending age

A

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

20
Q

Name the epochs in descending age

A

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

21
Q

What is the mnemonic device for the epochs

A

Pretty Eager Old Men Play Poker Hard (PEOMPPH)

22
Q

What period(s) is the age of invertebrates?

A

Cambrian and Ordovician

23
Q

What period(s) is the age of fish?

A

Silurian and Devonian

24
Q

What periods are the age of amphibians?

A

Carboniferous and Permian

25
Q

What periods are the age of reptiles?

A

Triassic, Jurassic, and Cretaceous (Mesozoic era)

26
Q

What periods are the age of mammals?

A

Tertiary, Quaternary (Cenozoic era)

27
Q

When did the ice age cycles start?

A

2.6 million years ago

28
Q

When was there a meteor impact(dinosaurs died)?

A

66 million years ago

29
Q

When did pangaea form?

A

252 million years ago

30
Q

When was the explosion of life?

A

541 million years ago

31
Q

When did Earth form?

A

4.6 billion years ago

32
Q

How does the geologic time scale break down?

A

Eon-era-period-epoch

33
Q

What are the relative age dating rules?

A

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

34
Q

What is faunal succession?

A

Using index fossils to relatively date rocks.

35
Q

What is the rule of inclusions?

A

Inclusions are older than the rock that contains them.

36
Q

What are cross-cutting relationships?

A

The intrusion is younger than the rock they intrude.

37
Q

What is lateral continuity?

A

Sedimentary layers continue horizontally over a distance.

38
Q

What is superposition?

A

The oldest sedimentary layers are on the bottom.

39
Q

What is original horizontality?

A

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

40
Q

What is the difference between relative and absolute
age dating?

A

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.

41
Q

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

A

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

42
Q

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

A

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.

ES Finals (8 decks)

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