Unit 7 Review Geotime

uniformitarianism
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Terms in this set (27)
uniformitarianism
concept that processes that have shaped the Earth in the past are essentially the same as those operating today
Image: uniformitarianism
relative dating
process by which rocks are placed in their proper sequence or order; Only the chronological order of events is determined, not the absolute age in years
Image: relative dating
low of superposition
in an undeformed sequence of sedimentary rocks, each layer is older than the one above it and younger than the one below it.
Image: low of superposition
principle of original horizontally
layers of sediment are generally deposited in a horizontal position; Rock layers that are flat means that they have not been disturbed.
Image: principle of original horizontally
principle of cross-cutting relationships
when a fault cuts through rock layers, or magma intrudes into other rocks and hardens, then the fault or intrusion is younger than the rocks around it
Image: principle of cross-cutting relationships
unconformity
gap in the rock record
Image: unconformity
correlation
establishing the equivalence of rocks of similar age in different areas
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fossil
Fossils will be found most commonly in sedimentary rocks.
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index fossil
match rocks of the same age in different regions
Image: index fossil
half-life
the time required for one half of the atoms of a radioactive substance to decay
Image: half-life
radiometric datingthe procedure of calculating the absolute ages of rocks and minerals that contain radioactive isotopesradiocarbon datingmethod for determining agen(up to 75,000 years) by comparing the amount of carbon-14 to the amount of carbon-12 in a samplegeologic time scalethe division of Earth history into blocks of time - eons, eras, periods, and epochs; The time scale was created using relative dating principles.eonthe largest ime unit on the geologic time scale, next in order of magnitude above eraPrecambrian timethe long time span from Earth's formation tothe beginning of the Cambrian period; made up of the Hadean, Archaean, and Proterozoic eons.eraa major division on the geologic time scale: Ears are divided into shorter units called periods.perioda basic unit of geologic time scale that is a subdivision of an era: Periods may be divided into smaller units called epochs.epocha unit of geologic time scale that is a subdivision of a periodWhat is important to form a fossil?Rapid burial and hard parts.PhaneroziocVisible lifePaleozoicAncient life540 million years agoWhen did abundant fossil evidence appear in the geologic record?What follows the Precambrian era?PaleozoicIn the early Paleozoic, life was found where?SeasIn what era did Pangea start to break apart?MesoziocDimosaurs where around in what era?MesozoicDevonianage of fishes and ferns 400 million years ago

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