coal

• Coal:

  • Formed from peat deposits 
  • Needs land plants 
  • Anoxic environments 
  • Rapid burial 
• Warm wet environments have the most prolific plant growth - carboniferous swamps. 
• A succession of cyclothems are formed as the delta subsides due to sediment weight, or the sequence is reset if the sea level rises. 
• Peat is the initial stage in coal formation - dark, brown and spongy formed from partial decay of plant material. 
• Coalification is when Peat is compacted by weight of overburden of sediments, water is squeezed out. Oxygen is lost as CO2 and H2O. Hydrogen is lost as methane. 
• 10m of peat makes 1m of coal. 
• Coal has to be more than 50% carbon. 
• Coal contains impurities like sulphur, chlorine and trace amounts of dirt and other elements. 
• Coal rank describes the extent of geologic changes since deposition. 

  • Low rank ---> high rank 
  • Dull ---> shiny 
  • Hardness increases 
  • Carbon content increases 
• Lignite - brown, woody and dull 
• Bituminous - black with banding and shiny 
• Anthracite - very hard, black, shiny and high density 
• Reserves is amount of a resource that can be extracted at a profit. 
• Coal is the most abundant fossil fuel. 
• Lignite it the most polluting due to being high in sulphur.