1. Water Vapor (H₂O): Volcanic outgassing was a major source of water vapor in the early atmosphere.
2. Carbon Dioxide (CO₂): Also released by volcanoes, carbon dioxide was a significant component of the early atmosphere.
It's important to note that the early atmosphere was very different from today's. It lacked significant amounts of oxygen (O₂), which is essential for most life forms today. Oxygen was slowly generated by early photosynthetic organisms over billions of years.
