The Formation of Coal The vegetation of swamps must fall and be buried in an

The formation of coal the vegetation of swamps must

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° ° The Formation of Coal ° -The vegetation of swamps must fall and be buried in an oxygen-poor environment. ° -Compaction and partial decay of the vegetation transforms it into peat. (Is a form of energy in other parts of the world) ° -To transform peat into coal, the peat must be buried deeply (4-10km) by overlying sediment. ° -At a certain depth, the weight of overlying sediment compact the peat and squeezes out any remaining water. ° -Temperature increases with depth, deeply buried peat gradually heats up. ° -Heat accelerates chemical reactions that gradually destroy plant fibers and release elements in the form of gas. ° -The gases seep out of the peat layer, leaving behind a residue concentrated with carbon. Once the carbon proportion of the residue exceeds 50%, the deposits become coal. ° -Process continues, highest grade coal: anthracite. ° ° Phanerozoic Ice Ages and CO 2 ° ° -Impact of burning fossil fuels °
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° ° ° Graph: ° - Temperature are in relative terms to present day ° - Left side: deltao18: Measure of the isotopic composition of oxygen. (2 isotopes: o16 and o18) Ocean water has a consistent o16 o18 ratio Ratio changes as temperature of ocean changes With water vapour, o16 goes with it. The heavier isotope stays behind. As the temperature of the ocean changes, the isotopic composition of the ocean will change. We can measure this by looking at fossil organisms (shells). We can measure the isotopic ratio from these shells and minerals, and therefore can find the composition of the sea water- from there we can find temperature. The measure of proportion o18/o16, gives a temperature measure. ° -Lows: ice ages. Interesting point: we’re in the middle of an ice age right now. ° -Within ice ages, there are periods of interglacial periods (temporary warming before deep freeze). ° -4 major ice ages going back 500M years. ° ° CO2 content on earth °
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° ° ° -CO2 content has been much higher in the past. ° -Because we’re in the middle of an ice age. ° -The fuss: humans are increasing it very rapidly ° - There has been time when the whole planet has been free of ice (even at poles). ° Other times, the whole earth has been covered by ice. ° ° Temperature on Planet Earth ° ° °
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° -For the last 15k years, the temperatures have been climbing, and then they go flate. Prediction: much higher. ° -The concern: we’rve had a million years of modest fluctuations, and then not its taking off because of us. ° ° CO2 Concentration vs. Temperature: ° ° ° -Tracked remarkably well. ° -Dating comes from ice precisely ° -Complete record of the deltao18 (the proportion of 18 to 16, which tracks temperature perfectly. Tracks ocean temperature. ° -They measure the CO2 content (because air gets trapped) ° ° -Reason for concern: Over 400k years, there’s been a predictable pattern (up to 280 ppm). Now CO2 concentrations are high. -If temperature is going to follow CO2, we’ll have all sorts of impacts.
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  • Fall '09
  • Sedimentary rocks, rocks

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