1. Geologic Time Scale (GTS)
a record of the major events and diversity of life forms present in Earth’s history
It divides Earth’s long history into units of time
Personal Time Scale
Geologic Time Introduction

2. On your “personal time scale”…
Try to place the following in order (youngest on top, oldest on the bottom):
My grandparents got married.
I took a breath.
I started kindergarten
I woke up this morning.
My parents were born.
My grandparents were born.
My grandparents met each other.
I was born.
I ate or drank something.
I learned to walk.
I started 4th grade.
I learned to read.

3. Units of Time on the GTS
Fill in the “number of years ago” column using the style of the Geologic Time Scale…
ya= stands for “years ago”
So, you “took a breath” 0 ya
While your grandparents were born ~65 ya

4. Units of Time
Longest
Precambrian Time
Eon
Era
Period
Shortest
Epoch

5. Units of Time on the GTS
So, let’s try to separate our Personal Time Scale into:
1 Era
2 Periods
12 epochs
Which unit of time are we missing?

6. Units of Time
Precambrian is the name given to the earliest span of time in Earth history.
Geologists divide the time between Precambrian and the present into three long units called eras:
Paleozoic era
Mesozoic era
Cenozoic era These are all part of the Phanerozoic Eon

7. How is the GTS made?
Subdivisions are based on large scale events in Earth’s history that are identified in the fossil record and rock layers.
At the end of each era a mass extinction occurred, many kinds of organisms died out, although there were other extinctions going on during each period of geologic time.
The layers of rock on Earth serve as evidence when identifying the geologic time scale. Using the fossil record, paleontologists have created a picture of the different types of common organisms in each geologic period.

8. End of an Era Evidence- choose a color
Causes of Extinction- choose a color

9. TLC- Prehistoric Earth
Fill in Video notes on p. 21.

10. Paleozoic Era Fill in your notes as we watch the video clip…

11. Mesozoic Era Fill in your notes as we watch the video clip…

12. Mesozoic

13. Cenozoic

14. Paleozoic