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24 Cards in this Set
- Front
- Back
hiatus
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a break or gap in the rock record
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In undistributed layers of rock where are the oldest layers?
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at the bottom
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What are some evidence of events on earth?
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igneous intrusions and extrusions
faults, joints, folds internal characteristics |
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What isotopes are useful in dating?
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Carbon-14
Uranium-238 |
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What steps combine in seqwuence to produce an unconformity?
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uplift, erosion, subsidence, and depostition
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What are the ages of rock compared to their surronding?
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rock fragments found in larger rock masses are older the n surronding rock
cracks viens and mineral cement are younger then surronding rock |
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What are the perferable types of index fossils?
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lived over the entire earth for relatively short periods of time
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What is the most reliable fossil evidence?
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index fossils
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vien
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a mineral deposit that has filed a crack
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What isotope does not combine chemically with any other element?
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argon 40
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What species first occured in the Paleozoic era?
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intervertebrates, fishes, amphibians, vertebrates, and land plats and animals
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Why are unconformities useful?
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they indicate a geologic event of some magnitude took place
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Explain the history of the atmosphere
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500 million years ago the earth's interior was solid, earth heated and melted the solid materials, as earth cooled the crust developed
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nonconformity
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interfaces formed when sedimentary rocks are deposited on top of an eroded surface of igneous rocks
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How can potassium 40 be used to date a rock?
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by comparing the amounts of argon 40 and potzassuium 40, the age can be determined
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When using the potasium- argon dating system which determines the age of the rock?
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The more Agron 40 in the rock, the older the rock
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How was earth born?
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as a cloud of gases and dust left over fro m the creation of the sun
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What was the primary source of gases of Earth's earliest atmosphere?
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outgassing by volcanoes.
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How long have have humans been in existence?
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.04% of the 4.5 billion years
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What does the mesozoic era provide evidence of?
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dinosaurs, earliest birds and mammals
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What is necessary for fossils to survive?
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must be buried soon after death and have hard shells, bones,m or teeth
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angular unconformities
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tilted, folded,or faulted rocks that have been eroded and covered again
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what determines the geographic history of an area?
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fossil evidence
age of rocks erosional record |
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parallel unconformities
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occur when parallel rock layers of different ages are seperated by an erosional surface
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