History of the Earth

Did you know that the Earth is about 4 to 6 billion years old? How do scientists know that the Earth is that old? That is ancient! Well, scientists use rocks and fossils as evidence to tell them many things. The age of rocks can be determined very reliably. Fossils provide information about life and conditions of the past. Watch this short video that gives a quick summary of the past 4-6 billion years here on planet Earth.





Again, how do scientists know the age of the Earth? Well, they are able to determine major events in the Earth's history by using a geologic time scale, which is a system of chronological (time) measurement based on the study of the planet's rock layers. All of the layers of rock at the Earth's surface contain evidence of life during the times at which each layer was formed. By studying this rock record from the very beginning, it is possible to determine many things about life on Earth, as well as the age of the Earth.
As you can see from the picture below, as scientists look at and study different layers of the Earth, they can learn a lot about life and how the Earth has existed these past few billion years!