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Flashcards in Fossil Record Deck (20)
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1

uniformitarianism

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

2

catastrophic

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 (or the same atomic number) as other atoms of the same element do but that has a different number of neutrons (and a different atomic mass)

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 process

11

trace fossil

a fossilized mark formed in soft sediment by the movement of an animal

12

mold

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

13

cast

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

14

unconformity

a break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time

15

mass extinction

The extinction of a large number of species within a relatively short period of geological time, thought to be due to factors such as a catastrophic global event or widespread environmental change that occurs too rapidly for most species to adapt.

16

Jurassic period

lasting for 55 million years during which dinosaurs and ammonites flourished.

17

Cretaceous period

a period of the Mesozoic Era, from 140 million to 65 million years ago, characterized by the greatest development and subsequent extinction of dinosaurs and the advent of flowering plants and modern insects.

18

Devonian period

a geological time during which a system of rocks formed. The trees are particularly important

19

Quaternary period

a current period of geologic time, which began about 1.8 million years ago. ... The Quaternary period is the name for the time in which we live.

20

Permian period

a Gymnosperms evolved, the first modern conifers appeared, and reptiles diversified. The Permian Period ended with the largest known mass extinction in the history of life. It wiped out nearly 90 percent of known marine life forms.