ESCI 1120 Study Guide - Midterm Guide: Lake Huron, Cenozoic, Plate Tectonics
17 May 2018
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Exam 2: Ice Ages and the Glaciation of Canada October 3, 2017
• Ice ages are periods that are characterized by cold periods
• They last tens of millions of years
• In part to the amount of greenhouse gases in the atmosphere
• Plate tectonics are all good reasons to get these ice ages
• Why does the ice age temperature change?
o Answer: Variations of the orbit around the sun
• First ice ages:
o Huronian ice age (North shore of Lake Huron)
o 2.1 to 2.5 billion years ago
o Glacial sediment, Non Glacial, glacial, non, etc.
o Ice ages also evident in Australia, South Africa, Amazon, etc.
o In Canada, the best evidence for these ancient ice ages is the Huronian deposits in an
area along what is now the north shore of Lake Huron
• Present Ice Age:
o The Late Cenozoic
o Began when Australia and South America broke away from Antarctica
o About 40 million years ago
o Allowed a current to flow around most of Antarctica and to isolate it from the warmer
water to the north
o Cooling increased as a result, and Antarctica was ice covered by about 20 Ma (million)
o Large ice sheets did not appear in North America and northern Europe, however, until
about 2 to 3 Ma ago
o Only a small portion (western) that is a real concern to flood If it melts
Within the Present Ice Age (Late Cenozoic):
• This latter part of the Late Cenozoic (when large ice sheets formed in Canada and northern
Europe) is known as the Pleistocene (ended at Holocene)
o About 2.6 million to 12,000 years ago
• Also called the Quaternary
o About 2.6 million years ago to the present
• The Holocene = postglacial period, started 12,000 years ago
• Quarernary period = Pleistocene + Holocene put together
o A period characterized by as many as 17 to 20 major alternations of warm and cold
periods and retreat / advance of ice sheets
• Intervals that are as warm as today are known as interglacial stages while cooler periods and
massive ice sheets are known as glacial stages
o Last glacial stage since an interglacial stage in North America is known as the Wisconsin
o Warmer periods within a glacial stage (but too cool to be considered interglacial) are
interstadials
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• A few interglacial stages were as warm as today, and some even warmer (about 125,000 years
ago) were even warmer (2 – 2.5 degrees C warmer)
• Proof of this is in The Don Beds (Toronto area) contain remains of plants and animals that show
the temperature during the last interglacial was 2 to 2.5 degrees C higher than today.
• Sea level is closely related to temperature
During Glacial Stages → sea level fell to about 80 to 120M below its present level (due to large
quantities of water trapped in the ice)
Interglacial → like today, it rose to its current levels when ice sheets melted (although higher by 3 to 6m
than today)
• Land is depressed by weight of the overlying ice in glacial stages
• In most of Canada, relative sea level has fallen in the last ten of thousands of years (Holocene)
o This is because land formerly under thick ice has been uplifted more rapidly than the
rise in sea level (which has fallen)
Quaternary (Pleistocene) Ice Sheets
• Two massive ice sheets developed in the Northern Hemisphere during glacial stages
o The Laurentide Ice Sheet: in Central and Eastern Canada
▪ Developed first on Baffin Island
▪ Southwestern Arctic, American Midwest & Yukon were NOT glaciated (dry)
o Fennoscandia Ice Sheet: Scandinavia, Finland, Scotland, Germany, etc. (Europe)
• A second large ice sheet developed in western Canada
• Cordilleran ice sheet was the result of ice flowing into the interior plateau of B.C. from Coast
Mountains to the west, the Rockies, and associated ranges to the east.
• Third large ice sheet in high Arctic islands of Canada
3 Current Glaciers in Canada:
1. Northeastern Arctic
2. Coast Mountains of B.C. and Yukon
3. Eastern Rockies
3 Interglacial Periods:
1. Antarctica
2. Greenland
3. Mountains
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find more resources at oneclass.com
7 Glacial Periods:
1. Antarctica
2. Greenland
3. Mountains
4. Laurentide
5. Cordilleran
6. Arctic
7. Femo-seadian
Glacial isostasy: areas adjacent to the thick ice are sinking down (e.g. New York, Boston, London →
Interglacial) → Most of Canada is going up though
Georgian Bay: Stones (limestones) are the same, but discoloured because the beach is like a giant
conveyer belt; constantly rising and moving new stone which is exposed to elements (ice, water, etc.)
Topic 2: Glacial → Slides
• Glaciers develop above the snowline → in the accumulation zone
• Snow Line → it is the lowest point at which snow can persist throughout the years
o This is where glaciers will develop due to the continuous build-up of snow
• Accumulation → layers that vary in thickness that depend on how hot the summer was, how
cold the winter was
• Transforming fresh snow from winter to glacial ice
o If you are only reliant on pressure, it will take hundreds of thousands of years for this
process to work
o We only get pressure alone in very cold places (e.g. Antarctica)
o If we add in meltwater (e.g. Canadian Rockies, European Alpes), we have both pressure
and meltwater
o Meltwater seeps down in the spaces, freezes, and compacts much more quickly →
maybe looking at a few years, not very long compared to pressure alone
o A. Cold Ice → Fos e slo glaies dot oe uikl o do uh at all
o B. Warm Ice → Fast ice, much more erosion, much more deposition
• Two zones separated by snow line:
o Accumulation Zone
o Ablation Zones
• Two things determine Snow Line: Temperature and Wetness
• Glacier is a transport system that takes the ice from above the snow line, and moves it down.
• Increase snowfall → drop snowline → glaciers advance
• Decrease snowfall → Higher Snowline → glaciers retreat (See diagraph on glacial)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Exam 2: ice ages and the glaciation of canada. Ice ages also evident in australia, south africa, amazon, etc. Within the present ice age (late cenozoic): this latter part of the late cenozoic (when large ice sheets formed in canada and northern. During glacial stages sea level fell to about 80 to 120m below its present level (due to large quantities of water trapped in the ice) Interglacial like today, it rose to its current levels when ice sheets melted (although higher by 3 to 6m than today) Land is depressed by weight of the overlying ice in glacial stages. Mountains to the west, the rockies, and associated ranges to the east: third large ice sheet in high arctic islands of canada. 3 current glaciers in canada: northeastern arctic, coast mountains of b. c. and yukon, eastern rockies. 7 glacial periods: antarctica, greenland, mountains, laurentide, cordilleran, arctic, femo-seadian.
