The Geologic

Time Scale

A history of the Earth

How old is the Earth?

• 4.6 billion years!• 4,600,000,000• Divided into “eras”:

– Precambrian– Paleozoic– Mesozoic– Cenozoic

1.8 million years

4 x 1.8

= 7.2 million years

How long was the Paleozoic?544 MYA - 245 MYA

How long was the Paleozoic?544 MYA - 245 MYA

299 million years

How long was thePrecambrian?

299 million years

4,056 million years

299 million years

Wa r n i ng :

No t t o Sc a l e! !

To scale?

To scale?

How big was a a Sauroposeidon?

A scale timeline

• To appreciate the times involved in Earth’s history, we will make two scale timelines

• A set distance on the timeline represents the same amount of time (E.g. 1 cm = 1 year)

• Example: If this line represents your K-12 school career, where would you be now?

K 12

K 1 2 3 4 5 6 7 8 9 10 11 12

A scale timeline

• To appreciate the times involved in Earth’s history, we will make two scale timelines

• A set distance on the timeline represents the same amount of time (E.g. 1 cm = 1 year)

• Example: If this line represents your K-12 school career, where would you be now?

Scale Timeline of Earth’s HistoryPart I: Outdoor Timeline

• How old is Earth?• 4,600,000,000 years old

(4.6 billion years)

• Today’s time line scale: 1m = 100 million years

• 4.6 billion years = 46 meters

Ground Rules

• We stay together - no stragglers!• When I talk, you listen• Stay with your table partner and make

decisions as a pair

Scale Timeline of Earth’s HistoryPart II: Paper Timeline

• Today, you will create a scale timeline of Earth’s history on a long sheet of adding machine paper

• Scale: 1 inch = 100,000,000 years

• 4.6 billion years = 46 inches• E.g. Mr. Inman’s mother was born

1,625,000,000 years ago. Where would this be on the time line?

Scale Timeline of Earth’s HistoryPart II: Paper Timeline

You may use:• Meter sticks (even though we’re using inches)• Decimal inch rulers• Your textbooks• Copies from other textbooks

• The internet• You may compare your timeline to my sample,

but you can’t take a pencil there when you go!

Scale Timeline of Earth’s HistoryPart II: Paper Timeline

To clean up:• Return

– Meter sticks (even though we’re using inches)– Decimal inch rulers– Your textbooks– Copies from other textbooks

• Leave the computers running and open, but shut down the internet

• One member of each pair will keep the timeline until tomorrow

• Go back to original seats