Note 1: Do not park along the shoulder. Walk to waypoint 2 (GZ) from the parking lot. You cannot answer all questions from the posted coordinates.
Note 2: This location is not accessible to westbound Trans-Canada Highway travellers. Take the first/east highway exit onto Banff Avenue.
Note 3: "Found" logs will be deleted without notice if acceptable answers to the questions at the bottom of this page are not received within two days.
Note 4: You will need to pay admission if you do not hold a valid national park pass.
Tunnel Mountain (SW of GZ) Stoney Squaw Mountain (NW of GZ)
On either side of the Bow Valley, towering peaks soar into the sky. Against this backdrop, two less majestic mountains stand out conspicuously. Tunnel Mountain (SW of waypoint 2) and Stoney Squaw Mountain (NW, beyond the end of Compound Road) are a full kilometre shorter than their neighbours, Rundle and Cascade. They are roches moutonnées, and their distinctive shape is the product of being overwhelmed by advancing glaciers long ago.
“Roche moutonnée” is a French phrase that roughly translates to “sheepback”. (The history behind this odd name is complicated – you can read about it here.) This name is given to rocky outcrops that have been scoured by glaciers and eroded in distinctive ways. The “up ice” (stoss – where the glacier came from) slope is gentle and relatively smooth due to abrasion, while the “down ice” (lee – where the glacier was going) slope is steep and rough.
As the advancing glacier encounters a rocky hill, it slowly climbs up the stoss slope, polishing the rock smooth along the way. The great pressure caused by this friction causes some of the ice to melt and run off into cracks in the rock. Once the ice reaches the top of the rock, the pressure is reduced, as the ice is no longer obstructed or fighting gravity. With the friction reduced, the meltwater re-freezes in the cracks, effectively making the rock a part of the glacier. With continued advancement, the glacier “plucks” pieces of the rock away and deposits them further ahead, creating the rough, steep slope on the lee side of the rocky hill and giving roches moutonnées their distinctive shape.
In contrast to Tunnel Mountain and Stoney Squaw Mountain, the peaks that line the Bow Valley were tall enough that they avoided being overcome by the Bow Glacier during the Wisconsinan glaciation, 11,000 to 25,000 years ago.
Sources
- https://en.wikipedia.org/wiki/R%C3%B4che_moutonn%C3%A9e
- https://www.theatlantic.com/technology/archive/2017/07/roches-moutonnees/532971/
- http://www.geography-site.co.uk/pages/physical/glaciers/stria.html
- https://en.wikipedia.org/wiki/Bow_Glacier
- https://en.wikipedia.org/wiki/Wisconsin_glaciation
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To log this earthcache as found, first e-mail me the answers to the first three questions (don’t post them in your log!). You may log it as found without hearing a response from me, but e-mails with missing or poor answers may be deleted, and the cacher notified as to the reason(s) why.
Questions
1. Identify the stoss and lee slopes of Tunnel Mountain and Stoney Squaw Mountain. Based on their orientation, in what compass direction was the Bow Glacier travelling when it passed through this area?
2. Where do you see a third roche moutonnée in the area? Does it appear taller or shorter than the other two? (Hint: It's not Sulphur Mountain.)
3. Your elevation at GZ is 1,395 m. The summit of Cascade Mountain (due north of GZ) is 2,998 m above sea level. Estimate the height the glacier must have been when it passed through this area (i.e. from valley floor to top of glacier). For reference, Stoney Squaw Mountain reaches 1,852 m above sea level.
4. (Optional) Post a photo of yourself with your favourite roche mountonnée in the background.
FTF: mikefromcanmore
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