2. Monday December 9,2013 Do Now: Iron oxides are chemicals composed of iron and oxygen. Scientist found that sedimentary rocks prior to 3.5 billion years ago did not contain iron oxides. This information is an indicator or clue about the atmosphere 3.5 billion years ago. Would you expect to find oxygen in the atmosphere 3.5 billion years ago? Today 1.Do Now 2.Major events in Earth’s history 3.Complete geologic time webquest. Homework 1.Cornell notes section 30.1 2.Unit 4 test Tuesday- binders can be used for the test Reminder 1.Do Nows are grade weekly and can not be made up. 2.Engagement points are graded weekly

3. What is the Earth’s time scale? The Geological time scale is a record of the life forms and geological events in Earth’s history. Scientists developed the time scale by studying rock layers and fossils world wide. Radioactive dating helped determine the absolute divisions in the time scale.

4. Divisions of Geologic Time Eras are subdivided into periods...periods are subdivided into epochs. Era Period Epoch E + P = EP

6. FOUR Eras… PRE-CAMBRIAN – 88% of earth’s history Paleozoic (ancient life) 544 million years ago…lasted 300 million yrs Mesozoic (middle life) 245 million years ago…lasted 180 million yrs Cenozoic (recent life) 65 million years ago…continues through present day

7. Earth’s Major Events The formation of Earth 4.6 BYA The Big Bang Theory videovideo

8. First Life 3.8 BYA – simple unicellular bacteria Anaerobic & did not photosynthesize

9. Great Oxidation/ Catastrophe Event Cyanobacteria-3500 BYA- Archean Eon Oxygen accumulates in atmosphere- 2.4 BYA- Proterozoic Era Greatest Extinction

10. Cambrian Explosion Biodiversity Increases 543 MYA- Paleozoic era began and the Cambrian period video video

11. Permian Triassic Extinction 252 MYA Ended the Paleozoic Era & Permian period 96 % marine species & 70% terrestrial species were wiped out

12. Mesozoic Era Cretaceous Tertiary Extinction 65 MYA- end of the Cretaceous period and Mesozoic era. Beginning of the Cenozoic era & Tertiary period. 50 % of plants and animals were wiped out

13. Last Ice Age 1.8 MYA- Cenozoic Era, Quaternary period, Pleistocene Epoch

14. First Homo Sapiens 200,000 YA- Cenozoic Era, Quaternary Period, Holocene Epoch