Cards (7)

  • why is evidence for the early atmosphere limited?
    • it was 4.6 billion years ago
  • how was Earth's early atmosphere formed?
    • volcanic activity released gases: carbon dioxide, nitrogen, water vapour, methane, ammonia
    • early atmosphere was made up of mostly carbon dioxide
  • what happened when oceans formed & how?
    • Earth cooled & water vapour in the atmosphere condensed
    • carbon dioxide dissolved in the oceans
    • the dissolved carbon dioxide went through a series of reactions to form carbonate precipitates that formed sediments on the sea bed
  • how did oxygen increase?
    • plants & algae evolved
    • they absorbed carbon dioxide & released oxygen bc of photosynthesis
  • equation for photosynthesis
    carbon dioxide + water -> glucose + oxygen
  • how did carbon dioxide decrease?
    • algae & plants absorbed carbon dioxide by photosynthesis
    • formation of sedementary rocks trapped carbon dioxide
    • dissolved in oceans
  • describe how deposits of limestone, coal, crude oil & natural gas were formed
    • plankton died
    • organisms were covered by sediments
    • subjected to high temperature & pressure