Bio 201 S10 Lect 2 (True) v2r

2 goodsummaryofmajorerasperiodsandevents

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Unformatted text preview: C ra9o decreases »  Half‐life = 5700 years •  How do we date fossil evidence? Isotopes of other elements are used for longer 9meframes –  Requires igneous rocks nearby (embedded) in the sedimentary rocks »  40K/40Ar ra9o used for most events in ancient evolu9on of life »  [half life =~1.25 billion yrs] –  Or if no igneous rocks nearby »  Paleomagne9c da9ng »  ‐record of known reversals of Earth’s magne9c field preserved in sedimentary and igneous rocks •  Table 21.2 –  Good summary of major eras, periods, and events in Earth’s history »  D...
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This note was uploaded on 02/18/2010 for the course BIO 201 taught by Professor True during the Spring '08 term at SUNY Stony Brook.

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