science

erin

How glaciers carved Lake Louise & the Rockies: what remains today

Everywhere, the Canadian Rockies are scoured and marked by the power of ice. We have these powerful glaciers to thank for much of the beauty we now enjoy. Banff NP’s Lake Louise at 1,731m elevation is one example of one such famous site created by glacial erosion.

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The Victoria Glacier above the head of Lake Louise, feeds the glacial lake with meltwater.

Above the head of the lake lies Victoria Glacier, a valley glacier, which feeds Lake Louise with beautiful blue-green meltwater (Britannica). Years ago, the Victoria glacier probably once extended much further into the valley while only a fraction of it remains today.

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The end of the trail approaching the head of Lake Louise. Beyond this point the trail crosses avalanche paths. It appears not everyone heeded the warnings; see footprints litter the snow just beyond the sign.

 

 

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The mini-avalanche we witnessed at Lake Louise still roared and crumbled despite the small size of the collapse. I still wouldn’t want to be anywhere near it! These falls must happen regularly based on the debris pile at the bottom. Spring is avalanche season in the mountains.

You can get closer to the  Victoria Glacier on the Plain of Six Glaciers trail, but the latter part of the trail was closed to us (like a few others on our trip) due to potential avalanches. In fact, while we walked along the frozen lake, we witnessed a mini-avalanche on the opposite shore.

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Lake Louise still frozen in late April.

 

Even when frozen, the lake’s waters are blue because it is a glacial-fed lake. As glaciers grind up rocks above the lake, fine glacial silt is created and deposited into the lake by meltwater. The sediment is then suspended in the lake as it slowly settles to the bottom and the sunlight reflects off the sediment is what gives it such rich hues.

As we walked along the lake, Golden-mantled Ground Squirrels scurried along the edges of the frozen lake while Clark’s Nutcrackers were unperturbed by tourists, seeking out an easy meal.

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The small Golden-mantled Ground Squirrel, commonly confused with a chipmunk!
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Clark’s Nutcracker, not at all bothered by the noisy tourists.

While much of the ice that once existed is now gone, glaciers still persist in the Rockies high in the mountains and down alpine valleys. At 2,800m elevation, the Columbia Icefield exists today due to the buildup of the annual fall of 7m of snow; the accumulation of snow over time forms the icefield (Parks Canada).

Perched along the Continental Divide, the approximately 215 square kilometer icefield is a major source of freshwater in North America (Gadd, 2008). The Athabasca River, the North Saskatchewan River and the  Columbia River are all sourced from the icefield, their waters eventually reaching the Arctic, Atlantic and Pacific Oceans, respectively.

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Part of the Columbia Icefield in Jaser NP, AB. The Snow Glacier is the lumpy looking snow on the right of the photo. To the left of the glacier is the Snow Dome at 3,456m elevation which lies directly on the Alberta-British Columbia border.

 

From the top of the Icefield, seven valley glaciers flow downward, one of which is the easily accessible Athabasca Glacier. The Athabasca Glacier is currently retreating although it once reached as far as where the Icefields Visitor Center stands today (Gadd, 2008).

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The Athabasca Glacier, Columbia Icefields, Jasper NP, AB.

While glaciers are mighty erosive forces, they also deposit incredible loads of sediment. By studying the erosive features and deposits left behind by glacier, geologists can determine how far the glacier extended in the past.

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The Athabasca Glacier valley with some glacial features labelled. Glaciers scour through rock, leaving behind characteristic round-bottomed and steep-sided U-shaped valleys as opposed to rivers cutting out V-shaped valleys. (Click for full size image)

The Athabasca Glacier valley where the U-shape of the valley is clearly seen. Lateral moraines are piles of rock debris deposited along the edges of a glacier as it recedes. Here, they mark where the glacier extended much wider into the valley than it does today, almost outlining the glacier’s previous boundaries.

The rocky debris in the foreground of the photo (a recessional moraine) was deposited as the glacier retreated from a former position further into the valley; the land where I stood taking this photo was once covered by ice as recently as the early 1800s (Patton, 2014). A glacier retreats when melting occurs faster at the toe than snow and ice can accumulate further up on the glacier. Basically, it is like simple math. If what goes in (snowfall) is less than what goes out (melt), the glacier retreats.

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The North Saskatchewan River flows from the Rocky Mountains east toward Lake Winnipeg, its waters eventually reaching the Atlantic Ocean at the Hudson Bay via the Nelson River (Jasper NP, AB).

Freshwater is a critical resource not only for human survival, but flora and fauna of all kinds, and the Columbia Icefield is an important resource for all living things besides its simple beauty. The melting and building of the Columbia Icefield impacts what happens downstream in the Columbia River and as far away as the Arctic Ocean where the Mackenzie River (the largest and longest river in Canada) empties into its seas.

All things in nature are inter-connected. Wildlife is wild. When will more people realize this? Animals and plants do not recognize park, provincial or national boundaries. Wolves and bears protected within the park boundaries wander out where they are hunted and killed because legislation permits hunting these animals. Pollution does not stop at the border with Alberta because it is from British Columbia. Invasive species from the U.S. do not stop at a border crossing with Canada to get their passport stamped and approved. When will people work together as stewards and take responsibility for our impact, both positive and negative, on this earth before it is too late for everyone, including ourselves?

References
Columbia Icefield and Athabasca Glacier, Parks Canada
Gadd, B., 2008. Columbia Icefield, Athabasca Glacier in Canadian Rockies Geology Road Tours, pp. 335-342.
Lake Louise in: Encyclopedia Britannica
Patton, B., 2014. Icefields Parkway Driving Guide in Parkways of the Canadian Rockies.

erin

How the montane & thermal springs provide habitat in Banff’s iconic Bow Valley

The Bow Valley of Banff NP, which today provides a rich habitat we are familiar with, was once covered by glaciers and ice 20,000 years ago during a period of time known as the Last Glacial Maximum. Glaciers carved through the mountains, creating a U-shaped valley with a flat bottom and steep sides. These glaciers disappeared from the Bow Valley by about 13,000 years ago, beginning the development of today’s modern montane valley (Reasoner and Huber, 1999).

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The Bow River Valley on a rainy day in  Banff, AB, Banff NP viewed from Tunnel Mountain. The Vermillion Lakes (discussed below) are on the far right of the photo.

Canada’s oldest national park (established in 1887), Banff lies in the heart of the Rockies and the town of 8,000 residents sits in Bow River valley. The Bow River is sourced from the Bow Glacier, part of the Wapta Icefield and flows into Bow Lake before joining the South Saskatchewan River. The Bow Valley provides important montane habitat for a wide variety of wildlife, from birds and small mammals like squirrels all the way up to grizzly bear and elk.

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American Red Squirrels were commonly seen on forested hikes darting quickly among and up the trees, and were sometimes very noisy. Perhaps they were announcing potential predators (probably us humans) in the area.

With wetlands, grasslands and open forest, an alpine montane ecosystem like the Bow Valley lies below the subalpine zone and is generally warmer and snow-free in the winter, providing habitat for a large range of animals (Parks Canada). Unfortunately, the montane is also an area humans prefer to occupy, putting constant pressure on wildlife in the region.

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The Vermillion Lakes lie within the Bow River valley and provide habitat for many species. Birds I watched here included the Red-Winged Blackbird, Northern Shoveler, Buffleheads, Common Merganser, Canada Gees and Mallards.
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Northern Shoveler at the Vermillion Lakes, Banff NP.

Across the Bow River from the Vermillion Lakes, the Cave and Basin National Historic Site marks where the Banff Thermal springs were discovered and the location of the original baths. The water from the thermal springs provides a niche habitat for species not found elsewhere in the area, including killdeer, garter snakes,  introduced tropical fish and the endangered Banff Springs Snail (Parks Canada).

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The cave where Banff’s thermal springs were discovered at the Cave and Basin National Historic Site.

In the wetlands and lake below the cave, we were lucky to spy what we thought was a beaver in the water. Now I am not sure if it could be a muskrat. We spied his body moving through the water and then he climbed up on shore and began eating some twigs for a while before eventually moving away out of sight.

A beaver or muskrat (I am no longer sure!) in Banff NP, AB in the wetlands below the Cave and Basin Historic Site.
Among many other birds, I was pleased to spy a White-Winged Crossbill in the trees, a new bird and first sighting for me.

 

 

 

 

Around the town and the Bow Valley floor, Columbian Ground Squirrels were a common sight. Unlike tree-dwelling American Red squirrels, these ground squirrels dig burrows underground where they spend winter. Without the lush, warm habitat of the Bow Valley montane or the microclimate of the hotsprings, none of these animals would thrive in the cold Rocky Mountains.

Columbian Ground Squirrel, Banff NP, AB.
Columbian Ground Squirrel standing up attentively to warn others of potential threats (probably humans) Banff NP, AB.

 

References
Ecoregions of Banff National Park, Parks Canada
Reasoner, M.A. and U.M. Huber, 1999. Postglacial paleoenvironments of the upper Bow Valley, Banff National Park, Alberta, Canada. Quaternary Science Reviews 18.
Thermal Waters, Parks Canada

erin

Why does 400ppm matter? & what it has to do with the Pliocene

In May 2013, the Mauna Loa Observatory in Hawai’i recorded the first time global carbon dioxide levels surpassed 400ppm (parts per million). As of this Tuesday, we are sitting at 403.98ppm and have been over 400ppm for much of the last year (Scripps). This observatory has been measuring atmospheric carbon dioxide since 1958. So, you might ask, why is the number 400 so important?

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Average atmospheric carbon dioxide levels for the last 12 months at the Mauna Loa Observatory in Hawai’i. (From: Scripps Institution of Oceanography)

Basically, the answer is: the earth hasn’t seen such high levels of atmospheric carbon dioxide since the mid-Pliocene warm period. 3.3 to 3 billion years ago. During that time, the continents looked much like they do today, but otherwise, the world was quite different. The climate was 2-3°C warmer than it is today and sea level was 25m higher. The expansive ice-sheets of today’s Antarctica had just begun forming. As atmospheric carbon dioxide continues to climb, our world could start looking more like the Pliocene in the future. (Haywood and others, 2009)

Charles Lyell, an important historical figure in geology, once said “the present is the key to the past.” But it could also be said that the past is the key to the present. That is the case for the mid-Pliocene warm period. The hope is that the more that can be learned and understood about the earth in the past, the better the changes happening today can be understood.

A little more about the Pliocene
The Pliocene epoch covers the time between 5.4 and 2.5 million years before present. On the geological timescale, it precedes the Pleistocene epoch which is known for its repeated glaciations and being the time of the last great ice age. While it was significantly warmer during the Pliocene than it is today, the Pliocene actually encompasses a marked cooling from the preceding warm Miocene epoch. Much of today’s forests were grasslands then, creating ideal conditions for grazing mammals which were plentiful.

One of the biggest changes to occur during the Pliocene was the joining of North and South America by the Panama land bridge. This allowed the spread and mingling of many species which were previously isolated from each other. This probably had a big effect on ocean circulation and because ocean circulation is closely linked with climate, this may have impacted climate as well. (University of California Museum of Paleontology, Encyclopedia Britannica)