Earth's History

10 Important Events

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Great Oxidation

This event occurred 2 billion years ago. The Great Oxidation allowed the ozone layer to form, protecting life on Earth from ultraviolet radiation.

Life On Land

About 2 billion years ago organisms leave the ocean and begin to live life on land. many scientists believe that this event occurred much earlier.

Creation of Earth

There are many different theories as to how the Earth and the universe came be, one including the Big Bang. This theory suggests that the universe suddenly exploded from an abundance of mass and energy creating all of the planets, and will always constantly be expanding. The Big Bang occurred about 13.6 billion years ago and the Earth formed about 4.6 billion years ago.

Oceans Emerge

Around 4.2 billion years ago the oceans were created. Some believe that the oceans came from an enormous asteroid, although this date is disputed. Some scientists think the oceans emerged around 3.8 billion years ago.


1.25 billion years ago stromatolites came to be. Mats of bacteria reach their peak, and the amount of oxygen in the atmosphere begins to increase dramatically.

First Bacterial Life

The first bacterial and archean life on Earth occurred 3.5 billion years ago. Although once again many believe that this event happened much earlier.

Oxygen Catastrophe

This event took place about 2.4 billion years ago. The Oxygen Catastrophe caused earth's anaerobic inhabitants were mostly wiped out from a severe lack of oxygen.

Permian Extinction

The Permian Extinction happened 248 million years ago. This massive extinction wiped out 96% of all species that roamed among the earth.

Cambrian Explosion

530 million years ago the Cambrian Explosion begins. This was the rapid appearance of most major animal groups, including the trilobites.

Human Evolution

About 200,000 years ago us modern humans begin to evolve for the first time. This event is the most recent event on the geologic time scale today.