The layers of rock on Earth serve as evidence when identifying the geologic time scale. Using the fossil record, paleontologists have created a picture of the different types of common organisms in each geologic period.
The Geologic Time Scale
- Humans subdivide time into useable units such as our calendar year, months, weeks, and days; geologists also subdivide time. One way to distinguish and define each segment of time is by major geologic events and the appearance or disappearance of life-forms, starting with the formation of Earth.
- No one person or expert came up with the geologic time scale we use today. It developed by trial and error through the efforts of numerous scientists working for decades. As technology of dating methods improves, geologists will continue to make small but significant changes to the geologic time scale for years to come.
- Most sections of geologic time are marked by major mass extinctions. The end of each era of Earth's history so far for example has ended with a major mass extinction such as the extinction of the dinosaurs. Below are some of the most significant extinction events that have already made their mark on Earth's geologic history.
The Geologic Time Scale Can Be Represented in Many Different Ways
Examine Some Examples of the Geologic Time Scale
Examine each of the geologic time scales below. Start to familiarize yourself with how they are organized.
What are some of the similarities they have? What are some of the differences?
You don't necessarily have to memorize them. Just learn how to USE them.
What are some of the similarities they have? What are some of the differences?
You don't necessarily have to memorize them. Just learn how to USE them.
Explore this detailed representation of the geologic time scale. You can zoom in and out to any geologic time you wish!
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