Geologic Timeline

      Three very important events in earth's history were the first prokaryotes, the Cambrian explosion, and the Permian-Triassic Extinction. Prokaryotes were the first life forms on earth, so I believe that the creation of the first prokaryotes was extremely significant, as they paved the way for life on earth. If they have never been created, life on earth may not exist now or be as diverse as it is. The Cambrian explosion was radiation of a lot of species, and when a lot of complex fossils began to appear. This event was very a very important evolutionary event, and may have paved they way for many species we have now. Although the Permian-Triassic extinction was the largest mass extinction in history, it paved the way for a lot of new species. These species include dinosaurs, which are a very unique and valued part of earth's history.

      Earth was formed about 4.6 billion years ago, but it was just fire and no life. The simplest life appeared about 4 billion years ago and complex life forms only began to become more common about 542 million years ago. I was surprised by how large the amount of time was that we had no life or only prokaryotic cells. More complex life and life that we are more familiar with only showed up towards the end of the scale. 

      Even though humans have not been around for a long time, I believe that we have had a huge impact. We have changed the environment fundamentally by deforestation, pollution, etc. We have also affected not only the earth itself, but everything that lives on it as well. However I believe that when the human race is no longer dominant, our impacts may not have effects effects on the life then. I wonder what the future looks like for the earth. Was life before the humans really what we have estimated it to be like, or was it completely different?