Canada is concerned we had the Grenville Mountains and they were the tallest during this time.
They were formed during this time but they have eroded to the ground. It was very tropical as
well so there would not have been snow on the mountains.
In addition and combined with the 1st was the formation of glaciers and their melting. This is
how extensive the ice coverage was seen from the North Pole and now we are down to this. You
see this on the news all the time. I have to chuckle when I hear this because this process of
breaking away and melting at the edges has been ongoing since the Wisconsin Ice Age. At that
time all of Canada was under ice and since then it melted away. If Al Gore was around then he
would have been very alarmed at the speed that the glaciers were disappearing. What is going on
in manmade CO2 is more serious because it happens so quickly and I will show you how quickly
The composition of biomes is also different. This shows what the composition was when the ice
age prevailed. There was a large diversity of eco system types on the planet. Don’t think of the
last ice age as ‘Snowball Earth’. The vast majority of the planet was thriving and there were
rainforest, temperate grasslands, etc. In N. America a large part was ice free. The Laurentide ice
sheet went right over to Greenland and the Cordilleran ice sheet covered the Rocky Mountains.
The Rocky Mountains are around 80 million years old which isn’t that old. The rise of the
Rockies and extinction of the dinosaurs is why on the eastern flank of the mountains we have
beautiful fossil finds of dinosaur skeletons that used to live in those days. Snowball Earth is
different in how long it lasted and its extent. Life persisted and after the snowball melted it
rebounded and from a geological perspective such a major deep freeze could find its ending and
it couldn’t have lasted. The tilt of earth at that time was very different about 60 degrees and
today it is 23.5 degrees. Those are the 2 major ice sheets but notice how they are not going that
far down south. Where they were they had a major influence on the other climates of N.
America. Florida would not have been the place to go to for a semi-tropical vacation as it
snowed a lot. After the ice age and it began to retreat (10,000 years ago) species started to
migrate north. Why did species retract so far south? The climate was pushing a lot further
Continental glacier the peak about 11,500 BP. There was actually a connection between
South America, Middle America, and North America up to Alaska. Alaska was one of the few
areas that were ice free almost entirely during the last ice age. How could that be? It was like
the Mongolian dessert and there was not enough moisture there to have ice. The wind patterns
were changed and there was a major vortex on top of the 2 ice sheets that sucked in moisture.
We have the Arctic and Antarctic now that sucks in things like moisture and also pollutants
(CFCs) and that is why over the Antarctic we have a larger depletion of the ozone layer than
anywhere else. Once enough ice was over top of Canada and parts of the U.S. it developed a
vortex and sucked in the moisture around it at the time and left Alaska bone dry. Parts of
Vancouver and Queen Charlotte Islands were left dry as well. There were parts along the fringes
along the east coast that were not ice covered either because of the vortex. Where the coast lines
are now are not the same as they were then because so much moisture was drawn on the ice the
oceanic levels were lower.
BGYC61H3F.November.17.2008 Lecture 10 3