Presentation on theme: "Add this unit to your Table of contents!"— Presentation transcript:
1 Add this unit to your Table of contents! Geologic TimeAdd this unit to your Table of contents!
2 A 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??
3 Fossils 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.
4 How 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.
5 Geologic Time Scale Divisions of the Geologic Time Scale Precambrian EraPaleozoic EraMesozoic EraCenozoic Era
6 The Precambrian Era 4.6 billion years ago – 542 million years ago ~88% of the earth’s history
7 Major EventsFormation of the Earth’s crust from molten rockFirst appearance of life --- bacteria!First organisms could photosynthesize----Oxygenated atmosphereFirst multi-cellular organisms
8 Major Events MASS Extinction- widespread glaciation Geologists compared the Earth to a giant snowball during this time
9 DOMINATE ORGANISMS Bacteria Multicellular organisms Cyanobacteria and stromatolitesDOMINATE ORGANISMSBacteriaMulticellular organismsFossils found in South Australia
17 4.6 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%
18 The Mesozoic Era251 million years ago – 65.5 million years ago