Tuesday, November 10, 2020

Geology of the National Parks in Pictures - Canada's Jasper National Park

 My next series of posts about the Geology of the National Parks Through Pictures is from a trip we took over the summer of 2017 up to Canada and back down through Montana to hit a bunch of the glacial parks in the area. These include two Canadian National Parks.   

You can find more Geology of the National Parks Through Pictures as well as my Geological State Symbols Across America series at my website Dinojim.com.


Continuing our trip north from Banff National Park, we hit the southernmost feature of Jasper National Park. Just after crossing the park boundary along the Icefields Parkway you come to the Icefield Centre where you can park and walk practically up to an active glacier, called Athabasca Glacier. There are also tours available where they take special vehicles onto the glacier, but we opted just for the hike to the base of glacier. 

Although not currently visible from the parking lot, the Athabasca Glacier at one time reached far beyond where I am currently standing. The glacier is part of the Columbia Icefield which spreads for a total of 150 square miles across both Banff and Jasper National Parks as well as neighboring Hamber Provincial Park. 

Glaciers are very sensitive indicators of climate change, whether to a colder climate or a warmer one. If the climate is consistent the glacier will balanced, where the amount of melting is equal to the amount of accumulation of snow and ice. For a consistent climate the glacier will not change in size but slowly act like a conveyor belt carrying the rocks and debris it picks up towards the melting end of a glacier. At the toe of the glacier all of that debris (called till) is deposited into a pile called a moraine. If the climate is cooling, then the amount of snow and ice accumulation would be greater than the amount of melting and the glacier would grow. It will continue to grow until the end of the glacier reaches a warm enough temperature where the amount of melting will match the amount of accumulation. If the climate is warming, the opposite will take place with the amount of melting exceeding the amount of accumulation. The glacier with then shrink until either it finds a new balance point or completely melts away. 

With the current climate change crisis, the climate is warming at an incredible speed and the glaciers are recording this event, to their detriment. Many stewards for the glaciers across the globe, especially the more accessible ones, have been putting up signs to indicate how quickly the current glaciers are slowly sliding away. Unfortunately for Athabasca Glacier these signs had more often than not been destroyed by visitors but at least this one for 1982 still existed when we had visited in July of 2017. The first picture above represents where the glacier was in ~1977.

Upon coming over the hill of rock we are finally able to see the glacier. Where I am standing is approximately the place that the glacier extended to ~1992, and is the one of the closest spots I could get to the glacier from this direction. Up on the top of the glacier you can see the edge of the Columbia Icefield as the snow falls over the edge into the Athabasca Glacier at the top of the valley. You can actively see the glacial meltwater coming off the glacier and forming a river that flows down into the valley. 

When glaciers travel over the ground the bottom ice of the glacier is constantly freezing and thawing. In the process rocks, sands, powdered rock, and other things all get trapped in the ice. Then as the glacier slowly slides forward, all of the debris on the base of the glacier is dragged across the soil and rocks that are there. Eventually anything that can easily be moved is eroded away and all that is left is bedrock, which the rocks are then dragged across as well. This produces scratches across the rocks known as glacial striations, as seen here. If the glacier was no longer around, scientists can still use the striations to identify if there was a glacier there at one point in time and the direction that the glacier traveled by using these lines as a compass. As seen here, all of the lines point straight back to the glacier.


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