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23 Cards in this Set
- Front
- Back
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How are fossils created? three ways
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1) Burial
2) Mineralization/fossilization 3) Discovery/exposure |
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Becoming a fossil--mineralization
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-Mineralization is the replacement of organic matter by minerals nearby. organic remains can be replaced by minerals.
-Many body tissues have organic and inorganic materials. Jaws and teeth are more mineralized so they're more likely to remain |
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Relative Dating methods--6
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1) Stratigraphic correlation
2) Biostratigraphy/faunal correlation 3) Lithostratigraphy 4) Tephrostratigraphy 5) Geomagnetic polarity 6) Florine Dating |
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relative dating methods vs. chromometric dating methods
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1) relative dating methods: you date according to something else
2) Chromometric dating methods give it an exact date |
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Biostratigraphy/faunal correlation
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Relative dating method
-Dating the kind of deposits (biological deposits in rocks) found by fossils |
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Lithostratigraphy
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Relative dating method
-date how old the silt and sediment is -dating the geological deposits and their relative rock properties |
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Tephrostratigraphy
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Relative dating method
-Ash, volcanic run off dating -take chemical fingerprint of volcanic ash |
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Geomagnetic polarity
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Relative dating method
-Polarity switches by time. Rocks allign according to polarity, so we can see whether it is normal polarity or abnormal polarity |
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Chromatic dating methods- 2
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1) Dendrochronology-tree ring dating
2) Isotopic/radiometric methods |
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Eocene
Dates |
55-36 mya
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Paleocene
dates |
65mya-55mya
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Oligocene
dates |
36-23mya
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Miocene
dates |
23-5.5mya
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Pliocene
dates |
5.5-2.6mya
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Pleistocene
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2.6mya-10,000
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Holocene
dates |
10,000- now
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cenozoic
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era from 65 mya to present
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cenozoic is an era that has 5 epochs
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1. Paleocene
2. Eocene 3. Oligocene 4. Miocene 5. Pliocene 6. Pleistocene 7. Holocene |
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Isotopic/radiometric dating methods
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Isotopes decay into smaller atomic particles according to constant rate called a half life
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Three examples of Isotopic/radiometric dating methods
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1) Potassion Argon Dating
2) Radio Carbon Dating 3) Uranium Series Datin |
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Potassium Argon Dating 40K/40Ar
Approach Material Range Half life |
Approach is indirect
Material is volcanic Range is 10,000-Age of the Earth Half Life is 1.3 Billion years As potassium breaks down, the argon gets trapped in the rock. more time passes, more argon gets trapped in hardened rock. Sci's find rock, melt it and measure the ratio of potassium to argon |
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Radio Carbon Dating 14C
Approach Material Range Half Life |
Approach is direct
Material is organic (e.g. a bone or a shell) Range is a few hundred to about 40,000 yrs Half Life is 5,730 +/- 40 yrs 12C and 14C are emmitted into atmosphere, then absorbed by plants, which are eaten by animals. 12C breaks down and can be compared to unstabe 14C |
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Uranium Series Dating 230T/234U
Approach Material Range Half Life |
Approach is indirect
Material is limestone Range is from a fwe thousand years to 500,000 yrs |
