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30 Cards in this Set
- Front
- Back
fossil |
The preserved remains or traces of living things. |
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sedimentary rock |
The type of rock made from hardened sediment. |
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mold |
A fossil formed when an organism buried in sediment dissolves leaving a hollow area. |
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cast |
A fossil that is a solid copy of an organism's shape, formed when minerals seep into a mold. |
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petrified fossil |
A fossil in which minerals replace all or part of an organism. |
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carbon film |
A type of fossil consisting of an extremely thin coating of carbon on rock |
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trace fossil |
A type of fossil that provides evidence of the activities of ancient organisms. |
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paleontologist |
A scientist who studies fossils. |
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scientific theory |
A well tested concept. |
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evoluton |
The process by which living organisms gradually change over time. |
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extinct |
Describes an organism that no longer exists. |
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relative age |
The age of a rock compared to the ages of rock layers. |
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absolute age |
The age of a rock given as the number of years since the rock formed |
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law of superposition |
The geologic principle that states that in horizontal rock layers, each layer is older than the layer above it. |
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extrusion |
Lava that hardens on the surface. |
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intrusion |
Magma that forces its way into rock and hardens. |
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fault |
A break or crack in Earth's crust. |
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unconformity |
A place where an old, eroded rock surface is in contact with a newer rock layer. |
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index fossil |
Fossils of widely distributed organisms that lived briefly. |
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geologic time scale |
A record of the geological events and life forms in Earth's history. |
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era |
One of the three long units of geologic time between the Precambrian and the present. |
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period |
One of the units of geologic time into which are divided into eras. |
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comet |
A ball of ice an dust that orbits the sun. |
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continental drift |
The slow movement of continents over Earth's surface. |
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invertebrate |
An organism without a backbone. |
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vertebrate |
An organism with a backbone. |
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amphibian |
A vertebrate that spends half of its life on land, and half in water. |
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reptile |
A vertebrate with scaly skin that lays eggs with tough leathery shells. |
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mass extinction |
When many types of organisms become extinct at the same time. |
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mammal |
A vertebrate that feeds its young milk. |