What Is the "Great Oxidation Event" That Changed Earth?

Описание: This video is about a huge change that happened on Earth a long time ago called the Great Oxidation Event. For a very long time, Earth’s air had no oxygen and was actually poisonous to us. Then, tiny organisms called cyanobacteria started making oxygen as a waste product. At first, the oxygen just rusted the iron in the oceans, but eventually, the oceans couldn’t absorb any more, and oxygen started building up in the air. This was great for life that needs oxygen (like us!), but it was deadly for the life that already existed, causing a massive extinction event and even a global freeze. This event completely changed the planet and made it possible for more complex life to evolve.