Geologic History

1. Geologic History Precambrian Era Paleozoic Era Mesozoic Era Cenozoic Era

2. Geology – science of the earth’s structure • Geologic Time – history of the earth from its formation 4.6 billion years ago to present • Era – a major geologic time lasting 10s to 100s of million of years. • Oldest Era to the Most Recent Era: • Precambrian • Paleozoic • Mesozoic • Cenozoic

3. Breaking Up Each Era -each era is broken up into periods, named for the area where the rocks from the time period were first discovered

4. Videos Early History • http://www.youtube.com/watch?v=-2YEJBK9yJM • First 5 mins only

5. How old is the Earth? -Scientists cannot determine exactly how old the Earth is Why? -They use rocks and Earth’s oldest rocks have been destroyed or recycled by plate tectonics -The oldest rocks (4 billion years old) ever found were found in Canada near Great Slave Lake How? Radiometric Dating -they use what’s called radioactive isotopes naturally occurring in rocks and minerals on the Earth

6. So, how old is the Earth? 4.6 BILLION YEARS Give or take a few million years

7. Precambrian Era Canada-the land-chart 12 • 4.6 billion to 570 million years ago (earliest life) • areas of land and ocean developed and disappeared many times • the Canadian Shield was the first and largest landform in Canada • the rest of Canada formed hundreds of millions of years later • peaks of the Canadian Shield (mountains) were at one time 12,000m above sea level, NOW most peaks of the Canadian Shield are about 500m above sea level

8. Precambrian Era

9. Precambrian Era • Mount Thule on Baffin Island • is the highest peak reaching over 1700 m high. • folding, faulting and erosion were responsible for the changes over the eras • Folding: Bending of rock layers • Faulting: Movement along a crack (fault) or cracks in the earth’s crust • Erosion: Wearing away of the earth’s surface followed by the movement to other locations of the sediments

10. Precambrian Era

11. What were the major geological and biological events of this era? • Canadian Shield formed • Life begins on Earth – age of single and multi celled organisms

12. Canada’s Landform Regions

13. Paleozoic Era • 570 to 245 millions years ago • sediments were moved by rivers and deposited by shallow seas to surround the Canadian Shield • sediment is compressed to form sedimentary rock • North America (N.A.) was located by the equator during this time • Oil and gas deposits formed when N.A. was located here • Swamps turned into Coal mines in Nova Scotia • Pangaea formed 300 million years ago during this period

14. Pangaea

15. Pangaea

16. Paleozoic Era • in the beginning of the era the only living organisms were in the seas • at the end of the era there were plants and forests that began to develop • during the last 600 million years 5 mass extinctions occurred, the largest during this era where 80% of all sea life disappeared and animals/plants became extinct in large numbers • Do you think that Pangaea was the cause of this?

17. Major Geological and Biological Events: • this collision of the continents caused the formation of the Appalachian Mountains • Age of fish, insects and large swamps = coal • plants and animals on land

18. Mesozoic Era • 245 to 66 million years ago • the beginning of this era is marked with the breaking up of the super continent Pangaea • at times seas and swamps covered much of Western Canada • while under water new layers of sedimentary rock formed on top of older rock • Coast Range Mtns. formed when tectonic forces caused the Pacific Plate and the N.A. Plate to collide • Rocky Mountains formed from tectonic forces folding

20. Mesozoic Era • Innuitian Mtns. formed as the N.A. plate moved north • climate was warm enough to sustain dinosaurs and reptiles in huge forests and swamps • Dinosaur Provincial Park in Alberta is where many dinosaurs bones were found because of the great inland sea that was located east of the Rocky Mountains • the end of this era was marked with another mass extinction, where 50% of animals became extinct • no one is absolutely sure of the cause

21. Major Geological and Biological Events: • Innuitian Mountains formed • Age of reptiles and dinosaurs, plants, birds

22. Dinosaur Provincial Park, Alberta

23. Mesozoic Era • Have you heard of possible reasons for this extinction?

24. Cenozoic Era • 66 million yrs ago (present day, right now) • Canada’s landforms took their present shape so did all the other continents • mountains continue to form through folding, faulting and volcanoes - the Rocky Mountains formation completed • seas disappeared to form the Interior Plains • an ice age during the last 2 million years occurred covering a large portion of the Earth • huge masses of ice called glaciers moved across the earth like ‘giant bulldozers’ scraping and gouging the land they covered • How was Canada affected?

25. Major Geological and Biological Events: • Rocky Mountains and Western Cordilleraformed and we had an Ice Age • Human beings developed and age of mammals

26. To get a better understanding of Geologic time, the 4 different eras and to discover what events occurred in each era Cenozoic (1%) -Rocky Mtns form -ice sheets cover NA Paleozoic (7%) -large parts of NA covered by water -Appalachians formed Precambrian (88%) -Shields formed -Canadian, Brazilian, African and Australian Mesozoic (4%) -water drops in NA -Innuitian mtns form

27. Geologic History - Paragraph Discussion Over millions of years, how has Cobourg taken form? What elements from geologic history have shaped and formed Cobourg?

28. Homework • Read: “Canada’s Geologic History” • Complete questions #1-10 • Due TOMORROW!