Presentation on theme: "Add this unit to your Table of contents!"— Presentation transcript:
1Add this unit to your Table of contents! Geologic TimeAdd this unit to your Table of contents!
2A timeline of your education If we made a timeline of your education, where would you fall??What would we use as the scale?Grade levelK12K1234567891011124.6 billion years agoPresent dayWhere would you fall on the timeline of the Earth’s history??
3Fossils and Geologic Time The geologic time scale organizes geologic and evolutionary events.It is based on evidence in the fossil record and has been shaped by mass extinctions.
4How do extinctions shape Geologic Time? Mass extinction- A large number of species become extinctAfter a mass extinction, opportunities open for new life-forms to emerge.
5Geologic Time Scale Divisions of the Geologic Time Scale Precambrian EraPaleozoic EraMesozoic EraCenozoic Era
6The Precambrian Era 4.6 billion years ago – 542 million years ago ~88% of the earth’s history
7Major EventsFormation of the Earth’s crust from molten rockFirst appearance of life --- bacteria!First organisms could photosynthesize----Oxygenated atmosphereFirst multi-cellular organisms
8Major Events MASS Extinction- widespread glaciation Geologists compared the Earth to a giant snowball during this time
9DOMINATE ORGANISMS Bacteria Multicellular organisms Cyanobacteria and stromatolitesDOMINATE ORGANISMSBacteriaMulticellular organismsFossils found in South Australia
174.6 billion years ago – 542 million years ago Warm-up 10/16/131. What years did the Precambrian Era span?4.6 billion years ago – 542 million years ago2. What percentage of Earth’s history does the Precambrian Era account for?88%
18The Mesozoic Era251 million years ago – 65.5 million years ago