Earths History Flashcards

1
Q

how old is the earth

A

4.6 billion years old

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2
Q

what happened 3.9 billion years ago

A

the earth cooled and water condenses and fills oceans

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3
Q

when was the precambrian era

A

4.6BYA - 544 MYA

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4
Q

how many years ago do eukaryotic organisms appear

A

1.8 BYA

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5
Q

when was the Paleozoic era

A

544 MYA - 245 MYA

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6
Q

what happend during the first half of the paleozoic era

A

animals with backbones appear in the ocean and seeded plants appear on land

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7
Q

what happened in the middle of the paleozoic

A

4 legged amphibians are on land

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8
Q

what happened at the end of the paleozoic

A

reptiles begin to flourish on land

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9
Q

when was the mesozoic era

A

245 MYA - 66 MYA

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10
Q

what was the mesozoic famous for

A

dinosaurs and appearance of small mammals

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11
Q

which era had the theorized meteorite that killed the dinosaurs

A

mesozoic era

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12
Q

when was the cenozoic era

A

modern era

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13
Q

when did the first primates appear

A

30 MYA during the tertiary period

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14
Q

when did modern humans begin to appear

A

200,000 YA during the quaternary period

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15
Q

what are fossils

A

any trace or remainds of an organisms that has been preserved by natural processes

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16
Q

what are fossils used to determine

A

geography, environment, animals, plants, and behavior

17
Q

where are fossils found

A

sedimentary rock

18
Q

what is a trace fossil

A

marking left by an animal like a footprint

19
Q

what is a cast fossil

A

fossil in which mineral fill a space left by a decayed organism

20
Q

what is an imprint fossil

A

when a thin object falls into sediment and leaves mark when rock hardens

21
Q

what is a petrified fossil

A

when minerals penetrate and replace hard parts of an organism

22
Q

what are mold fossils

A

when organisms is buried in sediment and decays leaving an empty space

23
Q

what is an amber or ice fossil

A

when the entire organisms is trapped in tree sap or ice

24
Q

which layers are the oldest

A

the bottom layrs

25
fossil dating can determine _______ of appearance and extinction
order
26
what does radiometric fossil dating use
radioactive isotopes to date fossils
27
how is appropriate age determined
by comparing the isotope to th eelement it decays into
28
what is teh halflife of K-40
13 billion years
29
what is the halflife of carbon 14
5730 years