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18 Cards in this Set
- Front
- Back
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define absolute dating
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also known as isotopic dating
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atoms
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nucleus composed of protons and neutrons
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atomic number
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number of protons
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elements must have
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multiple isotopes (same number of protons, different number neutrons )
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radioactive decay
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isotopes are present - where protons/neutrons leave nucleus and energy is produced ( measured with geiger counter)
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what is a daughter
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atoms becomes a different element when the proton is lost
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isotopic dating
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determining the age of a rock through its radioactive elements
radioactive elements decay through time - proportional decay rate (half-life) -produce "unique" daughter products |
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Half-life
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amount of time required to reduce to amount of radioactive isotope by half
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best isotopes to use for dating
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40K found in micas feldspars, hornblends
has unique daughter product |
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best rocks to date
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igneous rocks - lava flows
metamorphic rocks |
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radiocarbon dating
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14C is a radioactive isotope of carbon
half life of 5730 years living matter incorporates 14C into tissues On dying 14C begins to decay |
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best materials for 14C dating
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archaelogical matterial, that is less than 40000 years ago
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geological time scale
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events through time; eras. periods. epochs
eras (4) precambrian - few fossils paleozoic - old life mesozoic - middle life cenozoic - new life |
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Weathering
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process that change the physical and chemical character of a rock near the Earths surface
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Erosion
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physical removal of rock particles by an agent such as a stream glacier
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weathering, erosion and slopes
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produces landscapes, made up of landforms
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Mechanical weathering
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breaks rocks into smaller pieces
physical change |
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chemical weathering
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decomposition of rocks from exposure to water and atmospheric gases (Co2, oxygen)
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