Geologic Timeline Reflection

1) One of the major events on Earth's history is Ordovician-Silurian Mass Extinction. According to the study, this is the third largest extinction. This extinction wiped out 85% of sea creatures, contributing to the loss of different species in the ocean. The exticntion is said to be caused by a huge ice sheet, which is a major factor that led to the decrease in sea level and climate change. Another major event on Earth's histtory is the Permian Mass Extinction. According to the study, this is by far the worst extinction. It is known as the great dying because it almost ended life on Earth. This extinction wiped out 96% of life, leaving only 4% of species alive on Earth. The third major event is the Cretaceous -Tertiary Mass Extinction. This event is famous for wiping out all the dinosaurs that once ruled Earth. This extinction also killed 76% of life on Earth. Without this extinction, there is a great chance that Earth is always going to be dominated by dinosaurs.

2) The scale of Earth's history is huge. The thing that surprised me is the fact that we, human, only appear during an extremely small fraction of Earth's history. Another thing that surprised me is how the mass extinctions did not wipe out all life on Earth.

3) We have a huge impact on Earth in a short time. We caused global warming, increase in air pollution, exessive usage of natural resources, and more. We are destroying are beautiful nature in the short time that human appears on Earth. I believe our actions will eventually lead to another mass extinction or even cause Earth to become a place humans can longer live in.

4) One question that I have is "Why are people saying that we are experiencing the sixth mass extinction? Is there any evidence?" Another question that I have is "How do species survive the mass extinction?"

http://ichef.bbci.co.uk/naturelibrary/images/ic/640x360/t/ty/tyrannosauridae/tyrannosauridae_1.jpg

http://nbmpub.com/blog/wp-content/uploads/2012/11/history-of-earth_spread.jpg

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