Geologic Time Scale Quiz - Free Printable

The image you provided appears to be a blank geological time scale chart. The chart is divided into columns for "Eon," "Era," "Period," "Epoch," and "m.y." (million years). This type of chart is used to organize the history of Earth's geologic time into hierarchical categories.

Solution Explanation:

To fill in this chart, we need to use the standard Geological Time Scale, which is the accepted framework for dividing Earth's history into various time intervals based on significant geological and biological events. Below is a breakdown of how to populate the chart:

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#### 1. Eon Column:
- Phanerozoic Eon: This is the most recent eon, spanning from about 541 million years ago to the present. It includes all life forms with hard parts (e.g., shells, bones).
- Proterozoic Eon: This eon spans from approximately 2,500 million years ago to 541 million years ago. It is characterized by the rise of oxygen levels and the first multicellular life.
- Archean Eon: This eon spans from approximately 4 billion years ago to 2,500 million years ago. It is marked by the formation of the first continents and the emergence of simple life forms.
- Hadean Eon: This is the earliest eon, spanning from the formation of Earth (about 4.6 billion years ago) to 4 billion years ago. It is characterized by extreme conditions and the absence of a stable atmosphere or life as we know it.

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#### 2. Era Column:
Each eon is further divided into eras. Here’s how they break down:

- Phanerozoic Eon:
- Cenozoic Era: 66 million years ago to present.
- Mesozoic Era: 252 million years ago to 66 million years ago.
- Paleozoic Era: 541 million years ago to 252 million years ago.

- Proterozoic Eon:
- Neoproterozoic Era: 1,000 million years ago to 541 million years ago.
- Mesoproterozoic Era: 1,600 million years ago to 1,000 million years ago.
- Paleoproterozoic Era: 2,500 million years ago to 1,600 million years ago.

- Archean Eon:
- Divided into informal periods but not typically categorized into formal eras.

- Hadean Eon:
- Not typically divided into formal eras.

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#### 3. Period Column:
Each era is further divided into periods. Here’s the breakdown:

- Cenozoic Era:
- Quaternary Period: 2.58 million years ago to present.
- Neogene Period: 23 million years ago to 2.58 million years ago.
- Paleogene Period: 66 million years ago to 23 million years ago.

- Mesozoic Era:
- Cretaceous Period: 145 million years ago to 66 million years ago.
- Jurassic Period: 201 million years ago to 145 million years ago.
- Triassic Period: 252 million years ago to 201 million years ago.

- Paleozoic Era:
- Permian Period: 299 million years ago to 252 million years ago.
- Carboniferous Period: 359 million years ago to 299 million years ago.
- Devonian Period: 419 million years ago to 359 million years ago.
- Silurian Period: 443 million years ago to 419 million years ago.
- Ordovician Period: 485 million years ago to 443 million years ago.
- Cambrian Period: 541 million years ago to 485 million years ago.

- Proterozoic Eon:
- Periods are less formally defined but can include:
- Tonian Period (part of Neoproterozoic).
- Cryogenian Period (part of Neoproterozoic).
- Ediacaran Period (part of Neoproterozoic).

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#### 4. Epoch Column:
Each period is further divided into epochs. Here’s an example for the Cenozoic Era:

- Quaternary Period:
- Holocene Epoch: 11,700 years ago to present.
- Pleistocene Epoch: 2.58 million years ago to 11,700 years ago.

- Neogene Period:
- Pliocene Epoch: 5.33 million years ago to 2.58 million years ago.
- Miocene Epoch: 23 million years ago to 5.33 million years ago.

- Paleogene Period:
- Oligocene Epoch: 33.9 million years ago to 23 million years ago.
- Eocene Epoch: 56 million years ago to 33.9 million years ago.
- Paleocene Epoch: 66 million years ago to 56 million years ago.

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#### 5. m.y. (Million Years) Column:
This column indicates the approximate start and end times for each division. For example:
- Quaternary Period: 2.58 million years ago to present.
- Cretaceous Period: 145 million years ago to 66 million years ago.
- Cambrian Period: 541 million years ago to 485 million years ago.

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Final Filled Chart:

Here’s how the chart would look when filled in:

| Eon | Era | Period | Epoch | m.y. |
|-------------------|-------------------|--------------------|-----------------------|----------------|
| Phanerozoic | Cenozoic | Quaternary | Holocene | 11.7 k.y. |
| | | | Pleistocene | 2.58 m.y. |
| | | Neogene | Pliocene | 5.33 m.y. |
| | | | Miocene | 23 m.y. |
| | | Paleogene | Oligocene | 33.9 m.y. |
| | | | Eocene | 56 m.y. |
| | | | Paleocene | 66 m.y. |
| | Mesozoic | Cretaceous | | 145–66 m.y. |
| | | Jurassic | | 201–145 m.y. |
| | | Triassic | | 252–201 m.y. |
| | Paleozoic | Permian | | 299–252 m.y. |
| | | Carboniferous | | 359–299 m.y. |
| | | Devonian | | 419–359 m.y. |
| | | Silurian | | 443–419 m.y. |
| | | Ordovician | | 485–443 m.y. |
| | | Cambrian | | 541–485 m.y. |
| Proterozoic | Neoproterozoic | Ediacaran | | 635–541 m.y. |
| | | Cryogenian | | 720–635 m.y. |
| | | Tonian | | 1,000–720 m.y. |
| | Mesoproterozoic | | | 1,600–1,000 m.y.|
| | Paleoproterozoic | | | 2,500–1,600 m.y.|
| Archean | | | | 4,000–2,500 m.y.|
| Hadean | | | | 4,600–4,000 m.y.|

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Final Answer:

The chart should be filled in with the divisions of geological time as described above. Each row represents a subdivision of time, starting from the largest unit (Eon) and moving to the smallest (Epoch), with corresponding time ranges in the "m.y." column.

\boxed{\text{See the detailed explanation above for the completed chart.}}