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21 Cards in this Set
- Front
- Back
Bishop Ussher
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used the bible to date the earth, said that it was about 6000 years old
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Catastrophism
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belief that worldwide events happened to create the earth, earth was 6000 years old, except that radioactive dating is wrong
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James Hutton
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observed sedimentation rates, said that the earth was older than 6000 years old
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Uniformitarianism
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process of the earth still happening today, except that it was slower now, no specific number of how old the earth is
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William Thompson
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assumed earth had been cooling steadily since made, called for 20 million year old earth
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John Joly
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assumed oceans had collected salts from erosion at a constant rate, calls for 90 million year old earth
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the Curies
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discovered radioactive dating, and estimates the earth to be 4.6 billion years old
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Absolute Dating
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gives an actual number, cant be used on all rocks, dependent on interactions of strong and weak nuclear forces
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Radioactive decay
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when a parent gives off an alpha particle (2 pro, 2 neut) from its nucleus and transforms to an entirely different element, comes at a very predicable rate
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one half life
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1:1
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two half lives
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1:3
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three half lives
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1:7
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four half lives
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1:15
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five half lives
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1:31
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six half lives
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1:63
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1/8 of a half life
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15:1
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1/4 of a half life
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7:1
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1/2 of a half life
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3:1
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Relative Dating
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gives ages only to relation to others
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Law of Superposition
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says that the sediment on the bottom is older than the sediment on the top
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Index fossils
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must be widesperad, short lived, easily fossilized and have bones
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