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Putting time into proportion
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These time scales are drawn to scale so you can compare the relative lengths of geologic time divisions.
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All of Earth history is represented in this time scale. Notice the immense amount of time that passed prior to the explosion of life that took place at the beginning of the Phanerozoic Eon, about 570 million years ago.
Click on time periods to see reconstructions of ancient Earth.
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Now we've narrowed our view down to just the last 570 million years. The Phanerozoic Eon is subdivided into three Eras, the Paleozoic, Mesozoic, and Cenozoic. The Eras are further broken up into Periods. Notice that even at this scale, the Cenozoic Era, also known as the "Age of the Mammals", is only a tiny portion of Earth history.
Click on time periods to see reconstructions of ancient Earth.
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Close-up: The
Cenozoic
Era
Here’s a close-up look at the last 66.4 million years. If you are wondering where us humans are, take a look at the Holocene Epoch. The Holocene Epoch began about 10,000 years ago and continues to the present. Virtually all written human history occurred in the Holocene, yet, at this scale, 10,000 years is such a brief period that it too small to draw! The entire record of human history would be narrower than a single pixel on your computer screen!
Click on time periods to see reconstructions of ancient Earth.
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Close-up: The
Pleistocene
and Holocene Periods
This time scale shows the Pleistocene and Holocene Epochs. The Pleistocene is commonly known as "The Ice Age". The Holocene Epoch includes all recorded human history. These two Epochs span just the last 1.6 million years.
Click on time periods to see reconstructions of ancient Earth.
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