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Flashcards in fossil record Deck (20)
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1

uniformitarianism

a principle that that states that geologic processes that occurred in the past can be explained by current geologic processes

2

catastrophism

a principle that states that geologic change occurs suddenly

3

paleontology

the scientific study of fossils

4

relative dating

any method of determining whether an event or object is older or younger than other events or objects

5

absolute dating

any method of measuring the age of an event or object in years

6

superposition

a principle that states that younger rocks lie above older rocks if the layers have not been disturbed

7

isotope

an atom that has the same number of protons as other atoms of the same element do but that has a different number of neutrons

8

radioactive decay

the process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element

9

half-life

the time needed for half of a sample of a radioactive substance to undergo radioactive decay

10

fossil

the remains or physical evidence of an organism preserved by geological processes

11

trace fossil

fossilized mark that is formed in soft sediment by movement of an animal

12

mold

mark or cavity made in a sedimentary surface by a shell or other body

13

cast

type of fossil that forms when sediments fill the cavity left by a decomposed organism

14

unconformity

surface of contact between two groups of unconformable strata

15

mass extinction

widespread and rapid decrease in biodiversity on earth

16

jurassic period

geologic time and system that spanned 56 million years from the end of the triassic period

17

cretaceous period

last and longest segment of the Mesozoic period

18

devonian period

geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian

19

Quaternary period

divided into two epochs: the Pleistocene (2.588 million years ago to 11.7 thousand years ago) and the Holocene (11.7 thousand years ago to today)

20

permian period

geologic period and system which spans 47 million years from the end of the Carboniferous Period 298.9 million years ago, to the beginning of the Triassic period