Monday, November 09, 2020

Geology of the National Parks in Pictures - Canada's Banff 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


I had never been to a Canadian National Park and I wasn't sure exactly what to expect. I'm still not entirely sure how they compare to the US National Parks. Our first park of the trip was to Banff just west of Calgary. There is an entire town within the National Park boundaries that seems to be part of the park, unlike in the US where towns are generally not considered as part of the park, even when located within the park. I would say that overall, this is an absolutely gorgeous park that I wouldn't hesitate a moment to return to. The amount of geology within the park is truly astounding so my plan is to only hit a couple of the geological highlights along our trip, going from south to north through the park.

Our first stop within the park was to the Banff Upper Hot Springs, which is a pool that uses water from the local hot springs. The water initially seeps into the ground in Mount Rundle's high western slopes (seen in the background), then works its way down into the ground through the sedimentary rock layers were it is slowly heated, pressurized, and enriched with local dissolved minerals (including sulphates, calcium, bicarbonate, magnesium, and sodium). After hundreds of years it then rises up towards the surface along the Sulphur Mountain Thrust Fault until it reaches the surface at one of the several outlets, including this one at the Upper Hot Springs. 

View of Cascade Mountain from the town of Banff. Cascade Mountain is made up of Devonian and Mississippian age rocks. Banff National Park is Canada's oldest national park and the third oldest park in the world. It is known mainly for its glacial landscape which includes more than 300 glaciers, however that number is quickly shrinking as the planet quickly heats up from climate change.

Geology of Cascade Mountain. Image courtesy of the Geological Survey of Canada.

Starting at the base of the mountain (at least as far down as we can see) is the Palliser Limestone. The Palliser limestone (aka Palliser Formation) is a Late Devonian (~360 million years old) that was deposited along a warm, coastal shelf environment, very similar to the Bahama Banks today. Then above that along the more eroded slopes is the Banff Shale. The Banff Shale (aka Banff Formation) is also a Late Devonian age deposit that was deposited in a sediment rich marine environment. And the top of the mountain is capped with the resistant Rundle limestone. The Rundle Limestone (aka the Rundle Group) is a Mississippian age (~340 million year old) limestone deposited in a marine environment. 

Moving our way north from Banff, we stopped at the Lake Louise area. We were able to take a hike outside the visitors center and up along the Bow River. Here we have a view off to the south west looking at the Canadian Rockies. The amount of glacial features within the park is simply astounding. Glaciers are giant blocks of ice that don't melt during the summer. Over time they build up from snow that eventually gets so big that it starts to flow down the side of a mountain within the previously existing river valleys. As it flows it erodes away the ground that it is flowing over. Here you can just glimpse one of the glaciers located between the mountains as well as the harshly carved mountains typical of glacial terrains. 

One of the goals of the trip was to do some paddle boarding on Moraine Lake, the lake in the valley neighboring Lake Louise. Despite the heavy traffic to the lake we were able to plan to come back during the evening hours and made it up to an almost solitary part of the lake where we could spend the evening with just us. Moraine Lake is a moraine dammed lake. The valley was carved out by glaciers initially. You can tell a glacial carved valley from a stream carved valley because a stream carved valley will typically have a "V" profile from the stream constantly eroding straight down at the point of the water contact. However, since a glacier often fills most, if not all, of the valley it will erode on all sides equally creating a "U" shaped valley. Glaciers also carry the sediment that they erode out within the ice. Eventually the ice melts when it reaches an elevation or a climate that is too warm for it. At this point the glacier acts like a conveyor belt, dropping all of the sediment it had been carrying along the way into one big pile called a moraine. That is what happened here. A glacier carved out the valley and as it was melting away it deposited a pile of sediment (glacial sediment is called till) at the end of the valley forming a dam for the lake to sit behind. 

Glaciers also have a tendency to rub along the ground with the rocks and sediments embedded within them grinding down the rocks to a fine flour. This is called glacial flour and it is actually what gives the lake its lovely turquoise color when the light reflects off of it (suspended sediments in the water). Here is another view of Moraine Lake, facing west off into the valley. 

Despite the constantly warming climate which we are faced with in todays world, there are still some glaciers that are present and easily visible within the park. Moving our way a little further north the glaciers have a tendency to get a bit bigger and more noticeable. We are now traveling along the Icefields Parkway, making a at Bow Lake. 

There are a couple of glaciers visible at Bow Lake including this one, Crowfoot Glacier along the southwestern edge of the lake. The glaciers visible in the park have a tendency to only be a small outlet from a much larger icefield further up the mountains that generally aren't visible from the road. The glaciers along Bow Lake are all part of the Wapta Icefield to the west. 

Even in July, these waters are COLD. You can see Bow Glacier in the back of the photo here at the foot of Bow Lake. Bow Lake is another moraine dammed lake, like Lake Louise. The mountains seen here in the distance are made up of Cambrian quartzites and shales (~530 million years old) overlain by Middle Cambrian Limestones (~510 million years old). 

There are several types of river systems that are possible depending on the environment in which they are found. Within this region you get a lot of braided rivers. The North Saskatchewan River is a prime example of this type of river system. A braided river is where at times the river has a ton of water and energy, specifically around the spring melt. This enables the river to transport large amounts of sediment, but only during this time. At other times of the year the amount of water isn't enough to transport all the sediment in the river, causing it to dump the sediment as the water levels decrease to a trickle of what they once were. What is left is a series of river channels that weave in and out of each other within the river bed around the piles of dropped sediment, like a braid. 

At the northern most limits of Banff National Park along the Icefields Parkway the road takes a sharp, hairpin turn that at that top of gives a fantastic view off to the south. Here you can look down the North Saskatchewan River valley and you can see the beautiful "U" shaped glacial valley right in the center with the smooth sweeping valley walls characteristic of glacial terrains. 


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