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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.

This chart is not to scale. A timeline to scale is a valuable tool but requires lots of space. There are many commercially available timelines that are scaled to represent all 4.5 billion years of earth's history. They tend to be over 10 feet long! We are currently working on our own version.

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


541 mya to Present

Cenozoic Era
66 mya to Present


2.58 mya to Present

.012 to present


2.58 mya to Present

2.58 to .012 mya
5.3 to 2.58 mya


66 to 2.58 mya

23 to 5.3 mya
34 to 23 mya
56 to 34 mya
66 to 56 mya
Mesozoic Era

252 mya to 66 mya
Cretaceous 145 mya to 66 mya
Jurassic 201 to 145 mya
Triassic 252 to 201 mya
Paleozoic Era
541 to 252 mya
Permian 299 to 252 mya
Carboniferous 359 to 299 mya
Devonian 419 to 359 mya
Silurian 444 to 419 mya
Ordovician 485 to 444 mya
Cambrian 541 to 485 mya
Precambrian Time
4,600 to 541 mya
Ediacaran Period 635 to 541 mya
Proterozoic Era 2,500 to 541 mya
Archaean 4,000 to 2,500 mya
Hadean 4,600 to 4,000 mya

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