Evolution of the atmosphere

• What is the composition of the Earth's atmosphere today?

  About 80% nitrogen and 20% oxygen, with other gases making up less than 1%.
• What role did volcanic activity play in the early atmosphere of Earth?

  Volcanic activity produced a carbon dioxide-rich atmosphere.
• How did algae and plants affect the levels of carbon dioxide and oxygen in the atmosphere?

  They reduced carbon dioxide levels and increased oxygen levels through photosynthesis.
• What is the current status of the theory regarding the evolution of Earth's atmosphere?

  It is considered a theory supported by evidence but not definitively proven.
• What was the state of Earth during the first billion years of its history?

  The Earth was dry with intense volcanic activity.
• What gases were produced by volcanic activity in the early atmosphere?

  Carbon dioxide, water vapor, nitrogen, methane, and ammonia.
• What happened to the carbon dioxide as the water vapor condensed into liquid water?

  Carbon dioxide dissolved in the oceans and formed carbon precipitates.
• When did the next major change in the atmosphere begin, and what initiated it?

  About 2.7 billion years ago, initiated by the appearance of algae.
• What process do algae and green plants use to affect atmospheric composition?

  Photosynthesis, which takes in carbon dioxide and produces oxygen.
• How did the burial of dead algae and plants contribute to the formation of fossil fuels?

  They became buried in sediment, which compressed over millions of years to form sedimentary rock, oil, and gas.
• What types of organisms primarily contribute to the formation of crude oil and natural gas?

  Dead plankton, which are tiny organisms that float in the ocean.
• What is coal primarily made from?

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

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

  • Intense volcanic activity produced carbon dioxide and other gases.
  • Water vapor condensed to form oceans, dissolving carbon dioxide.
  • Algae appeared around 2.7 billion years ago, followed by green plants.
  • Photosynthesis reduced carbon dioxide and increased oxygen levels.
  • Burial of organic matter formed sedimentary rock and fossil fuels.
• What is the significance of the changes in atmospheric composition for the evolution of life on Earth?

  It allowed for the evolution of more complex life forms, such as animals.
• What is the approximate age of the Earth?

  1. 6 billion years.
• Why is the current atmosphere composed mostly of nitrogen and oxygen?

  Due to the processes of photosynthesis and the burial of organic matter over billions of years.