1. Chapter 3: Changing Climates
3.1 The Great Cooling
Chapter 3: Changing Climates

2. Cypress Hills an island of forest within a sea of grassland
600-m thick section of sedimentary rock was not removed by the advancing ice sheet
rare record of Cenozoic Era sediments
provides scientists with a complete record of the last 65 million years of Alberta’s history.

3. Cenozoic Era Most recent Era on the Geological Time Scale
65 million years ago to present
2 periods:
Tertiary Period – 97 % -
Quaternary Period – 3%

4. The Beginning of a Cooling Trend
At the end of the Cretaceous Period….
The collision between the North American Plate and the Pacific Plate caused the North American Plate to migrate northward and its climate got colder
Eventually it was cold enough to cause glaciers and contribute to the Cretaceous Extinction
These glaciers carved jagged edges into the smooth mountain ranges that were formed when the 2 plates initially collided

5. The Retreating Sea The beginning of the Tertiary Period….
As the sea retreated to the south sediment full of dinosaur fossils was deposited
Run off from the new Rocky Mountain Range deposited sediment full of fossils from the bottom of the sea (ex. ammonite)

6. The Rise of Mammals
65 mya – the surviving mammals after the Cretaceous extinction were mainly rodents
65 mya to 40 mya – mammals diversify and flourish
40 mya – many new mammals appear
ancestors of modern hoofed herbivores, flesh-eating carnivores, and large brained primates

7. The Rise of Mammals 35 mya – grasslands dominate Alberta’s landscape
Spread of large herds of grazing species in the late Tertiary Period
As Alberta became cooler and drier, the deep and dense roots of grasses help them survive
Movement from wetlands let to an environment of giant herds of large grazing animals
Rhinoceroses, camels, giant pigs, elephants

8. Evidence of Cooling Trend
Evidence is found in sedimentary rocks
Presence of tropical plants and animal fossils in current day Polar regions indicates these places must have been much warmer in the past
Absence of tree pollen from current tropical landscapes indicates that the past climate was too cold for trees to survive

9. Evidence of Cooling Trend
Evidence is found in deep ocean sediment
Determining the oxygen-18 to oxygen-16 ratio allows average deep ocean temperature to be determined
The higher the ratio, the lower the average deep ocean temperature
See graph on page 372