Class 11 Geography, Chapter 1: Origin and Evolution of the Earth:3

 Development of Life:

  - Life began in the oceans about 3.5 billion years ago.

  - Photosynthetic organisms released oxygen, gradually changing the composition of the atmosphere.

  - The ozone layer formed, protecting life from harmful ultraviolet radiation.

 5. Geological Time Scale

- Divides Earth's history into eons, eras, periods, and epochs.

- Major divisions include the Precambrian (formation of Earth to 541 million years ago), Paleozoic, Mesozoic, and Cenozoic eras.

6. Conclusion

- Understanding the origin and evolution of the Earth helps in comprehending the present conditions and predicting future changes.

- The study of geology, paleontology, and related sciences provides insights into Earth's dynamic processes and history.