3.2 C: Geology = the Changing Earth 3.2 The Icy Epoch Flashcards
What is the Athabasca Dunes?
Alberta’s largest actively migrating sand dune
Located in northeastern Alberta, close to the Athabasca River
How long and wide is the Athabasca Dunes?
7 km long, 1.5 km wide, and up to 35 m deep
This vast size can create a sensation similar to being in the Sahara Desert
At what rate does the Athabasca Dunes migrate?
1.5 m per year
This migration is caused by prevailing winds and results in sandstorms
What natural features does the migrating sand bury?
Trees, ponds, streams, and lakes
The advancing sand creates a seemingly lifeless desert environment
What process created the Athabasca Dunes?
The movement of ice sheets
A sheet of ice over 1 km thick shaped Alberta’s landscape over the last 1.7 million years
How long ago did glaciers begin to advance on Alberta?
1.7 million years ago
This advance of glaciers significantly impacted the region’s geography
What period marks the beginning of the icy Pleistocene Epoch?
The end of the Tertiary Period, around 7 million years ago
This period is characterized by accumulating snow in polar regions
What is a glacier?
A large river of ice that forms on land and moves under the influence of gravity
Glaciers are formed from compacted layers of snow
What happens to snow in polar regions during the early Pleistocene Epoch?
Snow accumulates year after year and compacts into ice
This process leads to the formation of glaciers
What ironic relationship exists between the advancing sand and the ice sheets?
The advancing sand mimics the ice sheet that created it more than 18,000 years ago
This reflects the cyclical nature of geological processes
Where can Earth’s largest glaciers be found?
In the polar regions - the Greenland and Antarctic continental ice sheets.
What happens to ice sheets during the Pleistocene Epoch?
They reached a critical mass and began to slowly flow outward toward the equator like a viscous fluid.
What is the depth of ice accumulation at the centers of current massive continental ice sheets?
Over two kilometers.
What is the process called when huge chunks of ice break off and float away?
Calving.
During the Pleistocene Epoch, where else did snow accumulate besides the continental ice sheets?
In mountainous regions, resulting in mountain glaciers.
Fill in the blank: Ice accumulates at the centers of ice sheets to depths of over _______.
two kilometers
True or False: Icebergs are formed from the calving process of ice sheets.
True.
What is the characteristic behavior of ice sheets when they reach a critical mass?
They begin to flow outward.
What significant geological period is associated with the accumulation of ice in mountain regions?
Pleistocene Epoch.
Fill in the blank: The continental ice sheet covers most of _______.
Greenland
What is the visual analogy used to describe the process of calving?
As if the ice sheet were giving birth.
Where can Earth’s largest glaciers be found?
In the polar regions - the Greenland and Antarctic continental ice sheets.
What happens to ice sheets during the Pleistocene Epoch?
They reached a critical mass and began to slowly flow outward toward the equator like a viscous fluid.
What is the depth of ice accumulation at the centers of current massive continental ice sheets?
Over two kilometers.
What is the process called when huge chunks of ice break off and float away?
Calving.
During the Pleistocene Epoch, where else did snow accumulate besides the continental ice sheets?
In mountainous regions, resulting in mountain glaciers.
Fill in the blank: Ice accumulates at the centers of ice sheets to depths of over _______.
two kilometers
True or False: Icebergs are formed from the calving process of ice sheets.
True.
What is the characteristic behavior of ice sheets when they reach a critical mass?
They begin to flow outward.
What significant geological period is associated with the accumulation of ice in mountain regions?
Pleistocene Epoch.
Fill in the blank: The continental ice sheet covers most of _______.
Greenland
What is the visual analogy used to describe the process of calving?
As if the ice sheet were giving birth.
What is an ice age?
A period when ice sheets cover parts of the Northern and Southern Hemispheres.
Earth is currently in an ice age due to the presence of ice sheets in Antarctica and Greenland.
What do people typically mean when they refer to an ice age?
A time period during which continental ice sheets advance to cover large regions of North America and northern Europe, known as glaciations.
These periods are more accurately termed glaciations.
How many major glaciations were believed to have occurred during the Pleistocene Epoch?
At least four major glaciations.
The Pleistocene Epoch is characterized by these significant cold periods.
What types of large mammals roamed the Pleistocene landscape?
- Mammoths
- Modern horses
- Llamas
- Reindeer
- Camels
- Scavenger dogs
Fossils from regions like Medicine Hat, Alberta, and Walsh Valley, Saskatchewan, provide evidence of these animals.
Name some of the predators that stalked the large mammals during the Pleistocene.
- American lions
- Short-faced bears
- Sabre-toothed cats
- Birds with 8-metre wingspans
These predators were adapted to hunting the large grazing mammals of the time.
What are some examples of exotic Pleistocene giants?
- Woolly mammoths
- Woolly rhinoceroses
These species are notable examples of the large fauna that existed during the Pleistocene Epoch.
Fill in the blank: An ice age is technically defined as a period when _______ cover parts of the Northern and Southern Hemispheres.
ice sheets
True or False: The term glaciation refers to a period during which polar ice sheets retreat.
False
Glaciation refers to the advance of polar ice sheets, not their retreat.
What event marked the end of the Pleistocene Epoch?
The beginning of the Holocene Epoch
Name three examples of landforms that provide evidence of glaciation in Alberta’s past.
- Drums
- Teardrop shaped hills
- Glacial valleys
What is a drumlin?
A teardrop shaped hill formed by glacial activity
What caused the Rocky Mountains to have their characteristic jagged shape?
The glaciers of the Pleistocene Epoch
How do glaciers change the appearance of mountains?
By scraping and gouging the mountain as they flow
What happens to snow that accumulates on mountains during winter?
It is compacted to become ice
What is the term for the flow of ice down a mountain?
Glacial flow
What is glacial meltwater?
Water that comes from melting glaciers
True or False: The Rockies started out as jagged mountains.
False
Fill in the blank: The Wisconsin Glaciation left behind characteristic _______.
landforms
What is the zone of accumulation in a glacier?
The area where snow accumulates and turns into ice
What is the zone of ablation?
The area where ice melts and is replaced by flowing ice
What role does gravity play in glacier movement?
It causes the accumulating ice to flow down the mountain
What is significant about winter snowfall in the Rockies?
It often exceeds summer melting
What drastic cooling trend began during the Tertiary Period?
The cooling trend that continued into the Quaternary Period
What is the coldest epoch of the Quaternary Period?
The Pleistocene
When did repeated glaciations begin according to ice-core data?
1.7 million years ago
What is the most recent glaciation known as?
The Wisconsin Glaciation
How long did the Wisconsin Glaciation last?
Until 10,000 years ago
What continues to shape the world today?
Ice
Which two regions are dominated by enormous ice sheets?
- Antarctica
- Greenland
What natural feature continues to grind slowly in Alberta’s Rocky Mountains?
Mountain glaciers
What may the many retreating glaciers and ice sheets indicate?
A warming trend in recent years
What are two potential challenges resulting from recent warming trends?
- Rising sea levels
- Freshwater shortages
Fill in the blank: The coldest times during the Quaternary Period occurred in the _______.
Pleistocene
True or False: The Tertiary Period and the Quaternary Period are characterized by warming trends.
False
