Science B Unit 1 Vocab

Front 1

absolute age

Back 1

the age of a rock given as the number of years since the rock formed

Front 2

amphibian

Back 2

a vertebrate whose body temperature is determined by the temperature of its environment and that lives its early life in water and its adult life on land

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carbon cycle

Back 3

the circulation of carbon in various forms throughout nature

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carbon film

Back 4

a type of fossil consisting of an extremely thin coating of carbon on rock

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carbon sink

Back 5

anything that absorbs more carbon that it releases

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cast

Back 6

a fossil that is a solid copy of an organism’s shape, formed when minerals seep into a mold

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Cenozoic era

Back 7

third of the major eras of Earth’s history, beginning about 65.5 million years ago and extending to the present; during the Cenozoic, the continents assumed their modern configuration and Earth’s flora and fauna evolved toward those of the present

Front 8

comet

Back 8

a loose collection of ice and dust that orbits the sun, typically in a long, narrow orbit

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endangered species

Back 9

a species at high risk of extinction

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era

Back 10

one of the three long units of geologic time between the Precambrian and the present

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evolution

Back 11

change over time; the process by which modern organisms have descended from ancient organisms

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extinct

Back 12

term used to refer to a group of related organisms that has died out and has no living members

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extinction

Back 13

the dying out or termination of a species

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extrusion

Back 14

an igneous rock layer for med when lava flows onto Earth’s surface and hardens

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fault

Back 15

a break in Earth’s crust along which rocks move

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folding

Back 16

the permanent bending or curving of a previously flat layer of rock

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fossil

Back 17

preserved remains or traces of an organism that lived in the past

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geologic time scale

Back 18

a record of the geologic events and life forms in Earth’s history

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half-life

Back 19

the time it takes for half of the atoms of a radioactive element to decay

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index fossil

Back 20

fossil used for indexing and defining geologic periods

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intrusion

Back 21

an igneous rock layer formed when magma hardens beneath Earth’s surface

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invertebrate

Back 22

an animal without a backbone

Front 23

isotope

Back 23

atoms of the same element that have different numbers of neutrons

Front 24

law of superposition

Back 24

the geologic principle that states that in horizontal layers of sedimentary rock, each layer is older than the layer above it and younger that the layer below it

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mammal

Back 25

a vertebrate whose body temperature is regulated by its internal heat and that has skin covered with hair or fur and glands that produce milk to feed its young

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mass extinction

Back 26

when many types of living things become extinct at the same time

Front 27

Mesozoic era

Back 27

second of Earth’s three major geologic eras that began 251 million years ago and ended 65.5 million years ago; this era is best known as the time of the dinosaurs

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mold

Back 28

a type of fossil that is a hollow area in sediment in the shape of an organism or part of an organism

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natural selection

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the process through which individuals that are better adapted to their environments are more likely to survive and reproduce than other members of the species

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paleontologist

Back 30

a scientist who studies fossils to learn about organisms that lived long ago

Front 31

Paleozoic era

Back 31

a major interval of geologic time that began 542 million years ago and ended 251 million years ago with the greatest extinction event in Earth’s history

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period

Back 32

one of the units of geologic time into which geologists divide eras

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petrified fossil

Back 33

a fossil in which minerals replace all or part of an organism

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Precambrian

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period of time that extends from about 4.6 billion years ago (the point at which Earth began to form) to the beginning of the Cambrian period 542 million years ago

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radioactive

Back 35

When an atom's nucleus is unstable and will emit energy or particles in an attempt to become more stable.

Front 36

radioactive decay

Back 36

the process in which radioactive elements break down

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relative age

Back 37

the age of a rock compared to the ages of other rocks

Front 38

reptile

Back 38

a vertebrate whose temperature is determined by the temperature of its environment, that has lungs and scaly skin, and that lays eggs on land

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survival

Back 39

the act or fact of living or continuing longer than another person or thing

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trace fossil

Back 40

a type of fossil that provides evidence of the activities of ancient organisms

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unconformity

Back 41

a rock or sediment surface separating two layers of different ages

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vertebrate

Back 42

an animal with a backbone