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 299 million years How long was the Precambrian? 299 million years 4,056 million years War n i n g : 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 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 1 2 3 4 5 6 7 8 9 10 11 12 Scale Timeline of Earth’s History Part 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 History Part 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 History Part 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 History Part 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 .