Timeline of Evolution of Earth
| Time Period | Event |
|---|---|
| 4.6 billion years ago | Formation of the Earth from the solar nebula. |
| 4.5 billion years ago | Differentiation of the Earth into core, mantle, and crust layers. |
| 4.1 – 3.8 billion years ago | Late Heavy Bombardment period, with intense meteor impacts. |
| 4 billion years ago | Formation of the earliest oceans and solidification of the Earth’s crust. |
| 3.8 billion years ago | Earliest evidence of life on Earth (fossil record of single-celled microorganisms). |
| 2.7 billion years ago | Emergence of oxygen-producing cyanobacteria, leading to the gradual oxygenation of the atmosphere. |
| 2.5 billion years ago | Formation of the first stable continents and the onset of plate tectonics. |
| 1.8 billion years ago | Appearance of eukaryotic cells (cells with a nucleus). |
| 1 billion years ago | Development of multicellular organisms. |
| 541 million years ago | Start of the Phanerozoic Eon, characterized by the appearance of complex life forms with hard shells and skeletons (the “Cambrian Explosion”). |
| 470 million years ago | First plants and fungi colonize the land. |
| 360 million years ago | Emergence of the first amphibians. |
| 290 million years ago | First reptiles appear. |
| 230 million years ago | First dinosaurs evolve. |
| 200 million years ago | First mammals appear. |
| 66 million years ago | Mass extinction event leads to the extinction of dinosaurs and the rise of mammals. |
| 2.6 million years ago | Emergence of the earliest humans (genus Homo). |
Evolution of Earth Class 11 Geography Notes
The Earth is a remarkable planet that has undergone a fascinating journey of formation and evolution over billions of years. From its humble beginnings as a hot, molten sphere to the diverse and life-sustaining world we know today, the Earth has witnessed countless transformations shaped by cosmic events and geological processes.
Evolution of Earth Class 11 Geography Notes