Geological Time Scale

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Earth’s history is divided into units of time that make up a geological time scale which is divided into four major subdivisions:

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True

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Eons

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longest subdivisions; based on abundance of fossils

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Eras

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marked by significant worldwide changes in the types of fossils present in rocks

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Periods

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based on types of existing life globally at a particular time

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Epochs

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divided periods characterized by differences in life forms

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Geological time begins with a long span of time called Cambrian Time, which covers about 88 percent of Earth’s history and ended about 8 million years ago.

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False

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Scientists hypothesize that Earth formed roughly 4.6 billion years ago.

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True

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What is the time period of Precambrian Time?

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4.6 billion-544 million years ago

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Earliest life form to appear was ___________

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cyanobacteria

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oldest era divided into six periods of Precambrain Era

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Paleozoic era