1. Chapter 3: Changing Climates
3.2 The Icy Epoch
Chapter 3: Changing Climates

2. The Big Freeze
A cooling trend began in the Cretaceous Period and continued throughout the Tertiary Period
By the end of the Tertiary Period (1.7 mya) the climate became so cold that snow began o accumulate year after year in the Polar regions
This marked the beginning of the icy Pleistocene Epoch

3. The Big Freeze
The weight of the snow caused the lower layers of snow to become compacted into ice which formed glaciers
Glacier – a large river of ice that forms on land and moves under the influence of gravity

4. COntinental Glaciers
Very large glacier often more than 1 km thick, forms in polar regions
During the Pleistocene Epoch when these ice sheets reached a critical mass, they began to slowly flow outward toward the equator like a viscous fluid
Current continental glaciers cover nearly all of Antarctic and Greenland

5. As a continental glacier flows outward it eventually reaches the sea, where calving occurs

6. Alpine Glaciers Snow accumulated in mountainous regions
As these glaciers flow to lower altitudes the temperature increases causing ice to melt and flow into streams
In Alberta chances are good that the water coming out of your tap is glacial melt water

7. Alpine Glaciers
As the ice slowly flows it scrapes and gouges the rock below it
The original v-shaped valleys became u-shaped
The original dome shaped mountains became jagged

8. Are we in an Ice Age Right Now?
An ICE AGE is a period which ice sheets cover parts of the Northern and Southern hemisphere
Glaciation is a period during which polar ice sheets advance to cover large regions of North America and northern Europe

9. Ice Core Samples Ice cores contain bubbles of gases from the past
Similar to deep sea sediment cores
The ratio of oxygen-18 to oxygen-16 is calculated and the average temperature change can be charted

11. Glacial Evidence
As a continental ice sheet advances and then retreats, it leaves behind characteristic landforms
KAMES – created as glacier chunks fallen off the larger ice mass are left to melt in place
Found between Slave Lake and Fort Vermillion

12. Glacial Evidence Drumlins
As the ice sheet flow, till is sometimes deposited in streamlined shapes called drumlins
The tapered ends of the drumlins point in the direction the ice sheet flows
Found in Morley Flats

13. Glacial Evidence Sand Dunes
The advancing ice sheet plucked up enormous amounts of fine, clean sand, as it scraped and gouged its way across rocks
When the ice sheet melted, sandy water poured into a glacial lake
The glacial lake drained and left a huge deposit of sand

14. Glacial Evidence Athabasca Sand Dunes
Field of sand piled in the middle of green forests
7 km long, 1.5 km wide and up to 35 m deep
Migrates southward at a rate of 1.5 m per year!

15. Glaciers and Freshwater
Mountain glaciers and ice sheets have been melting
A warming trend has been linked to the burning of fossil fuels which is increasing the Greenhouse effect
As glaciers become obsolete so does our fresh water supply

16. Giants of the Pleistocene Epoch
LARGE mammals thrived
Fossils have been collected near Medicine Hat, Alberta and in the Walsh Valley, Saskatchewan