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| Pangea supercontinent from space, as it may have looked 300 million years ago. |
The Earth is a little over 4.5 billion years old, its oldest materials being 4.3 billion-year-old zircon crystals. Its earliest times were geologically violent, and it suffered constant bombardment from meteorites. When this ended, the Earth cooled and its surface solidified to a crust - the first solid rocks. There were no continents as yet, just a global ocean peppered with small islands. Erosion, sedimentation and volcanic activity - possibly assisted by more meteor impacts - eventually created small proto-continents which grew until they reached roughly their current size 2.5 billion years ago. The continents have since repeatedly collided and been torn apart, so maps of Earth in the distant past are quite different to today's.
The history of life on Earth began about 3.8 billion years ago, initially with single-celled prokaryotic cells, such as bacteria. Multicellular life evolved over a billion years later and it's only in the last 570 million years that the kind of life forms we are familiar with began to evolve, starting with arthropods, followed by fish 530 million years ago (Ma), land plants 475Ma and forests 385Ma. Mammals didn't evolve until 200Ma and our own species, Homo sapiens, only 200,000 years ago. So humans have been around for a mere 0.004% of the Earth's history.
In Breif Geological timeline :
During its dramatic 4.5 billion year history, Earth has gone through a series of major geological and biological changes. The timescale below highlights a number of notable prehistoric events and the geological periods in which they occurred. As things didn't get interesting from a biological perspective until around 570 million years ago, we've included a couple of zoomed in timelines to show the detail of more recent evolutionary history.| 4.6 billion years ago | The origin of the Earth |
|---|---|
| 3.8 billion years ago | First life arises |
| 2.1 billion years ago | Eukaryotes evolved |
| 1.1 billion years ago | First sexually reproducing organisms |
| 570 million years ago | First arthropods evolve |
| 530 million years ago | The first fish |
| 475 million years ago | First land plants |
| 385 million years ago | First forests |
| 370 million years ago | The first amphibians |
| 320 million years ago | The earliest reptiles |
| 225 million years ago | The dinosaurs evolve |
| 200 million years ago | The mammals evolve |
| 150 million years ago | First birds |
| 130 million years ago | Flowering plants evolve |
| 100 million years ago | The first bees evolve |
| 65 million years ago | Dinosaurs and ammonites become extinct |
| 14 million years ago | The first great apes appear |
| 2.5 million years ago | Genus Homo evolves |
| 200 thousand years ago | Our species, Homo sapiens evolves |
| 10 thousand years ago | End of the last Ice Age |
Organic Farming
