Page 129 - Science Course 3 (Book 2)

The Geological Time Scale Mo11-L4a: How was the Geologic Time
Scale Developed?
Lesson 4

eon
the longest units of geologic time.

In this topic, you will learn the following
lessons: era
Mo.11–L4a: How was the Geologic Time Scale a large division of geologic time that is smaller
Developed? than an eon.
Mo.11–L4b: What Causes Mass Extinction?
period
a until of geologic time smaller than an era.

How was the Geologic Time Scale
Mo11–L4a
Developed? epoch
KEY CONCEPTS: a division of geologic time smaller than a period.
1. How was the Geologic Time Scale Developed?
Era Period Epoch

Holocene
Vocabulary A-Z Quaternary Pleistocene

Let us learn some vocabulary Pliocene
CENOZOIC Tertiary Miocene

Oligocene
Eocene

Paleocene
Let’s Begin

Developing a Geologic Time Line

Geologists developed a time line called the geologic
time scale to organize Earth’s past.

Eons are the longest units of geologic time.

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