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34 Cards in this Set

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  • Back
ABSOLUTE AGE
Actual age of an object
AMBER
Hardened tree sap in which fossils may be preserved
ANGULAR UNCONFORMITY
Boundary between horizontal and tilted layers of rock
BEDDING PLANE
Boundary between two sedimentary rock layers
COPROLITE
Fossilized waste material from an animal
DISCONFORMITY
Boundary between layers of rock that have not been deposited continuously
EVOLUTION
Change of living things over time
GASTROLITH
Fossilized stone found within the digestive system of a dinosaur or other reptile
HALF-LIFE
Time required for half the mass of a radioactive element to decay into its daughter elements
INDEX FOSSIL
Guide fossil; fossil found in the rock layers of only one geologic age and is used to establish the age of the rock layers
LAW OF CROSSCUTTING PRINCIPLE
Principle that a fault or intrusion is always younger than the rock layers it cuts through
LAW OF SUPERPOSITION
Principle that a sedimentary rock layer is older than the layers above it and younger than the layers below it
MUMMIFICATION
Preservation of a dead organism by drying
NONCONFORMITY
Unconformity in which stratified rock rests on unstratified rock
PALEONTOLOGIST
Scientist who studies fossils
PALEONTOLOGY
Study of fossils
PETRIFICATION
Process in which organic materials are replaced by new materials
PRINCIPLE OF UNIFORMITARIANISM
Theory that geologic processes at work in the present were also at work in the past
RELATIVE AGE
Age of an object compared with the ages of other objects
TRACE FOSSIL
Fossil trace left by an ancient organism, such as a track, footprint, boring, or burrow
UNCONFORMITY
Break in the geologic record created when rock layers are removed by erosion
VARVE
Annual layer of sedimentary deposit on a lake bed
CENOZOIC ERA
The most recent geologic era, beginning 65 million years ago; the Age of Mammals
EPOCH
Subdivision of a geologic period
ERA
Largest unit of geologic time
GEOLOGIC COLUMN
Arrangement of rock layers based on the ages of the rocks
INVERTEBRATE
Animal without a backbone
ION
Atom or group of atoms that carries an electrical charge
MESOZOIC ERA
Geologic era that lasted from 248 to 65 million years ago, prior to the Cenozoic; the Age of Reptiles
PALEOZOIC ERA
Geologic era that followed Precambrian time, lasting from 540 million to 248 million years ago
PERIOD
Subdivision of geologic era
PRECAMBRIAN TIME
Earliest and longest geologic era, lasting from 4.6 billion to 540 million years ago
THEORY OF EVOLUTION
Theory that organisms change over time and that new organisms are derived from ancestral types
VERTEBRATE
Animal with a backbone