11.4: The Geologic Time Scale

The whole geologic history of the Earth divided into units of varying magnitude:

• Geologic time scale

• Eons

• Phanerozoic

• Eras

• Paleozoic

Tags

NGSS.MS-ESS1-4

These represent the greatest expanses of time on the geologic time scale.

• Geologic time scale

• Eons

• Phanerozoic

• Eras

• Paleozoic

Tags

NGSS.MS-ESS1-4

The eon that began 542 million years ago, a term that means visible life.

• Geologic time scale

• Eons

• Phanerozoic

• Eras

• Paleozoic

Tags

NGSS.MS-ESS1-4

Eons are divided into these smaller units:

• Geologic time scale

• Eons

• Phanerozoic

• Eras

• Paleozoic

Tags

NGSS.MS-ESS1-4

The earliest era within the Phanerozoic eon, meaning ancient life.

• Geologic time scale

• Eons

• Phanerozoic

• Eras

• Paleozoic

Tags

NGSS.MS-ESS1-4

The middle era within the Phanerozoic eon is the______________, meaning middle life.

• Mesozoic

• Periods

• Epochs

• Cenozoic

• Paleozoic

The most recent era within the Phanerozoic, meaning recent life.

• Mesozoic

• Periods

• Epochs

• Cenozoic

• Paleozoic

Each era can be further divided into:

• Mesozoic

• Periods

• Epochs

• Cenozoic

• Paleozoic

Each period can be divided still into smaller units called:

• Mesozoic

• Periods

• Epochs

• Cenozoic

• Paleozoic

Tags

NGSS.MS-ESS1-4

The two eons that occurred before the Cambrian together are often referred to as the:

• Mesozoic

• Periods

• Epochs

• Precambrian

• Paleozoic

Tags

NGSS.MS-ESS1-4