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 Geologic Time Line

Life in the Paleozoic Sea

The purpose of this geologic time line is to help you easily find in-depth information on eons, eras, and periods of earth’s history. We think it is convenient and useful to see the time periods all laid out in chart form. As a reference tool, you can easily note the sequence of the various divisions and the length of each unit of time relative to each other.

Eons, The biggest subdivisions are of course the longest lasting and most inclusive of these divisions.

Eras are the next largest categories represented here.

Periods are relatively shorter in time length. They are further broken down into Epochs which are not represented on this chart.

Just like the layers of the earth, the top divisions of the chart represent the most recent time. Moving down the chart, you go further and further back in time.

Geologic Time Line Chart

Mesozoic Dinosaur
Cenozioc Mammals

The names of each Eon, Era or Period are linked to pages that contain information on the geology, biology, and climate of that particular time. Simply click on the name of the time division for more detailed information about it.

Note: At present, information about individual epochs can be found within their respective periods.

Below the chart, you will find links to lesson plans and activities for kids related to the geologic time line.

Old Periods


543 mya to Present

Cenozoic Era
65 mya to Present


1.8 mya to Present



65 to 1.8 mya

Mesozoic Era

248 mya to 65 mya
Cretaceous 144 mya to 65 mya
Jurassic 206 to 144 mya
Triassic 248 to 206 mya
Paleozoic Era
543 to 248 mya
Permian 290 to 248 mya
Carboniferous 354 to 290 mya
Devonian 417 to 354 mya
Silurian 443 to 417 mya
Ordovician 490 to 443 mya
Cambrian 543 to 490 mya
Precambrian Time
4,500 to 543 mya
Ediacaran Period 635 to 540 mya
Proterozoic Era 2,500 to 543 mya
Archaean 3,800 to 2,500 mya
Hadean 4,500 to 3,800 mya

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Geologic Time Line related lesson plans, kid’s activities, and elementary level reading booklets.