How Lake Louise & Johnston Canyon Came to Be

Lake Louise seen from the Plain of Six Glaciers Trail, Sept. 2012

I’ve mentioned before that being in the Rockies awakened in me an interest in geology and earth history.  As I travelled, I wanted to learn how the mountains, lakes and canyons were formed.  Here’s a small bit of what I’ve gathered about Lake Louise and Johnston Canyon.

Johnston Canyon, Banff National Park, September 2012

Lake Louise, Sept. 2012, Alberta, Canada

Near the end of our travels, I bought a book to help in my learning called How Old is that Mountain by Chris Yorath.  From that book I’ve learned that Lake Louise may be a tarn.  And for those of you who have never heard of a tarn, as I had not until a short while ago,  it’s a lake that has formed at the base of a steeply walled recess—shaped like a deep bowl—on the side of a mountain.  These deep recesses are called cirques and are formed by mountain glaciers eroding the mountain’s rock.

In the case of Lake Louise, it’s possible that when the glacier on Mt. Victoria was much larger it carved Lake Louise’s basin.  This may have happened around 25,000 years ago.

Glacier Above Lake Louise, Sept. 2012–I believe this is Mt. Victoria Glacier

Here, the huge lengths of time geology deals with need to be put in terms that our minds can comprehend.  In geological terms, 25,000 years ago is very recent.  For example, scientists estimate that the earth was formed around four and a half billion years ago and that our human ancestors arrived around 3 million years ago.

To help us, Chris Yorath includes the following analogy.  If we imagine the entire history of the earth as a 24 hour clock, the creation of the planet would be at midnight—00:00.  And the appearance of humans would not be until well past 23:00 hours, at one minute and a few seconds before the following midnight.  This has certainly given me pause for reflection and helps me grasp that Lake Louise was formed in recent times.

Fine particles of sediment called rock flour at the edge of Lake Louise, Sept. 2012

Back to her now.  I learned, from information in Banff National Park that the beautiful green blue of Lake Louise and other Rocky Mountain lakes arises in large part from rock flour.  That is, from fine particles of sediment washing down from the mountains into the lake.  This was visible to us at the end of the lake closest to the Plain of Six Glaciers hike.

In the case of Johnston Canyon, Yorath reports that according to Parks Canada the canyon was created around 8,000 years ago.  At that time, a landslide that brought masses of rock down from a nearby mountain diverted Johnston Creek from its path.  Then, over time, the canyon, which is 200 metres deep, was carved out.

Looking down into Johnston Canyon in Banff National Park, September 2012

I alternate between contemplating geological and human time scales.  Either way, while I was in the presence of the mountains, lakes and canyons, I felt something very old, compared to my life, surrounding me.  Being part of nature in that way, experiencing that sense of time and change, was life giving.  Because of that, I hope to always draw on the memories of my time in the Rockies and to return to them again.