Evolution of The Atmosphere

• What is the composition of Earth's atmosphere?

  About 80% nitrogen and 20% oxygen
• What role did volcanic activity play in the early atmosphere?

  It created a carbon dioxide-rich atmosphere
• How did algae and plants affect atmospheric composition?

  They reduced CO2 and increased oxygen levels
• What is the current status of the theory regarding atmospheric evolution?

  It is supported by evidence but remains a theory
• How long has Earth been evolving its atmosphere?

  About 4.6 billion years
• What was the state of Earth during the first billion years?

  It was dry with intense volcanic activity
• What gases were produced by volcanic activity in early Earth?

  Carbon dioxide, water vapor, and nitrogen
• What happened to carbon dioxide as water vapor condensed?

  It dissolved in oceans and formed sediments
• When did algae begin to appear in Earth's history?

  About 2.7 billion years ago
• What process do algae and green plants use to produce oxygen?

  Photosynthesis
• How did the evolution of algae and plants impact life on Earth?

  It allowed more complex life forms to evolve
• What happens to algae and plants when they die?

  They become buried and form sedimentary rock
• What types of substances can form from buried organic material?

  Sedimentary rock, oil, and gas
• What is coal primarily made from?

  Thick deposits of dead plant material
• What is limestone primarily composed of?

  Calcium carbonate from marine organisms
• What are the key stages in the evolution of Earth's atmosphere?

  • Intense volcanic activity produced CO2 and other gases
  • Water vapor condensed to form oceans
  • Algae and plants evolved, reducing CO2 and increasing oxygen
  • Organic material became sedimentary rock and fossil fuels
• What is the current composition of Earth's atmosphere?

  Mostly nitrogen and oxygen
• Why is the theory of atmospheric evolution still considered a theory?

  Because it is based on evidence, not certainty
• How did the formation of oceans affect atmospheric carbon dioxide levels?

  It allowed CO2 to dissolve and reduce levels