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9 Cards in this Set
- Front
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Archives |
1. Instrumental- Central England temperatures started 1659 2. Historical- crop yield and correlation between yield and good weather conditions... Winchester -Historical pictures... Skating through time alexander hall... Thames iced over... photos- analyse glaciers 3. archaeological- collect sediment cores ... deep mud shows old climate... date sediment cores... used on oceans too |
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Absolute dating |
Tree rings, annually laminated sediments, annual ice layers Same for sediment cores- bands between mud, white band= summer... dark= winter |
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Radiometric dating |
1. Radioactive- time dependent decay -rate is known -rate of decay= half life - age measured by how much decay and how much remains 2. Radiocarbon dating (14C) -used quaternary -14c absorbed into surfaces -half life 5730 +- 40 years 3. U/TH- up to 1.5Ma 4. 210Pb- sediments, half life 22.3 yrs 5. artificial radionuclides |
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Age equivalence... |
TEPHRA- Volcanic ash - white in the core= ash |
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Proxies |
1. biological 2. physical 3. chemical 4. stable isotopes |
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1. Biological |
Interpretation on modern day ecology -ecological requirements unchanged -death assemblage reflects living community-taphonomy Macro remains- bones, beetles, charcoal... Hippo bones trafalgar sq. 120000 yrs ago
Micro remains- pollen- identification to plant/genus= analysed to record vegetation change Case study E America-18000 yrs ago boreal forest... large ice sheet... modern ice sheet has shrunk... -how quickly did ice sheets retreat? Elms- recolonised permafrost environments- 8000 yrs ago died out due to disease |
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Framinifera |
Imbrie and Kipp tried to estimate temp of ocean in last ice age |
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Drought reconstruction USA |
colonise Jamestown trees grew thick ring in warm summer and small when cold/drought when they colonised these area= huge drought |
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Stable isotopes |
same chemicals... different masses= ratios controlled by climate |
