An eon is the largest division of geologic time, encompassing billions of years. In the geologic time scale, an eon is divided into eras, which are further divided into periods, epochs, and ages. There are four main eons in Earth’s history:
- Hadean Eon: This eon lasted from about 4.6 billion to 4 billion years ago. It represents the time from Earth’s formation to the formation of the first rocks.
- Archean Eon: This eon lasted from about 4 billion to 2.5 billion years ago. It is characterized by the formation of the first continents and the emergence of life.
- Proterozoic Eon: This eon lasted from about 2.5 billion to 541 million years ago. It saw the development of more complex life forms and the oxygenation of the atmosphere.
- Phanerozoic Eon: This eon began about 541 million years ago and continues to the present day. It is marked by the rapid diversification of life and the development of modern ecosystems.
Each eon represents a significant span of time in Earth’s history, reflecting major changes in the planet’s geology, climate, and life forms.