Geologic Timeline Individual Reflection

          In class, we made a scaled timeline of Earth's history from the creation of Earth to the present. Three major events that happened in Earth's history were the creation of Earth, the formation of life, and the evolution of humans. The creation of the Earth is important because that is when Earth is formed. That leads to all the changes that happened after that. The formation of life is important because that led to all of the evolution of life that led to the extreme diversity in life and changed the planet. The evolution of humans is important because they are the most advanced organisms that have developed technology that is changing the Earth to this day.

          The scale of Earth's history is very large. What surprised me the most was the length of some of the eras, especially the periods in Precambrian era. Also what surprised me was the large amount of evolution and speciation that occurred all throughout Earth's history. My thoughts on human's impact on the Earth in such a short amount of time is that it is hard to comprehend. We have just been on this planet for about 200,000 years and the Earth has changed dramatically, whether it is climate change, or the urbanization of the world.
Some questions I have are why are the Precambrian eras and periods extremely long compared to the Post-Cambrian eras and periods. Also, I wonder what led to all 5 of the mass extinctions that happened.