Interpreting Geologic History- Earth Science – Flashcards
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which number best represents when humans are interfered to have first appeared on Earth?
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4
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Which group of organisms has the shortest record of life on Earth?
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Placodern fish
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Evidence indicates that 251 million years ago a mass extinction of many life-forms occurred on Earth. Which form of life became extinct at this time?
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tribolates
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Thin layers of volcanic ash act as excellent time markers in the correlation of bedrock because volcanic ash
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falls to Earth over a large area in a short period of time
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Which numbered layers most likely formed at the same time?
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3 and 5
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Organisms that later became good index fossils lived over a
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wide geographic area and existed for a short geologic time.
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What evidence suggests that a mass extinction of the dinosaurs occurred at the end f the Cretaceous period?
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An absence of dinosaur fossils in Paleocene bedrock
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Which radioactive element is used to determine the absolute age of late Pleistocene animals remains?
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carbon-14
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How much of an 800-gram sample of potassium 40-
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50 grams
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Most scientists believe Earth's early Archean atmosphere was formed primarily by gases released from
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volcanic eruptions
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What is inferred to be the main source of the free oxygen that first entered Earth's atmosphere?
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oxygen-producing organisms
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Which geologic event is inferred to gave occurred most recently?
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initial opening of the Atlantic Ocean
