As one drives towards the Canadian Rockies from Calgary, Mount Yamnuska, the flat-faced mountain, stands with its stunning sheer cliff face guarding the entrance to the Rockies.
Mount Yamnuska has always fascinated me. Each time we drive to the mountains (which is frequent), we see Yamnuska in ever changing glory. Sights include the contrast of green and grey in summer, cloud shadows moving across the cliff face, shrouded in swirling mist, and snow-capped in winter.
When I was a young boy, my Dad (a geologist), told me the cliffs of Mount Yamnuska were older than the slopes below. Now as a child, this concept was hard to understand, but it laid the groundwork for a lifelong fascination of Mount Yamnuska.
I first hiked up to the top of Mount Yamnuska at the age of 12 while at summer camp. I still have vivid memories of that Yamnuska hike. Peering down the flat-faced mountain cliffs with much trepidation, while laying as flat against the rock as possible.
This is probably where I first picked up some rather colourful vocabulary.
Yamnuska – The Flat-Faced Mountain’s Name
The name Yamnuska derives from the Stoney First Nations name of Îyâ Mnathka, meaning “flat-faced mountain”. However, Yamnuska is a misspelling and translates to “messy hair” (oops).
A recent plaque indicates the true translatable name of this flat-faced mountain is E-Yamnuska.
The official name is Mount Laurie, named after John Laurie, who was the founder of the Indian (First Nations) Association of Alberta. He was a strong advocate for First Nations’ rights and cultural preservation in Alberta.
Although the official name is Mount Laurie, Mount Yamnuska, or ‘Yam’ for short, is the common name. Even the road signs refer to it as Yamnuska.
Mount Yamnuska – The Flat-Faced Mountain’s Geology
What happened geologically to create the flat-faced look of Mount Yamnuska?
Middle Cambrian ‘Elden’ limestone, some 510 million years old, make up the upper cliffs of the flat-faced mountain. These rocks derived from marine deposits near the equator in an ancient time between the existence of the Proterozoic and Pangea super-continents (think tropics, coral & tiny ancient sea creatures).
The lower slopes however, are made up of 75-million-year-old Upper Cretaceous ‘Belly River’ sandstone. These rocks were formed from sand and mud deposits near shallow seas (during the time of the dinosaurs).
Yes, you read that right; the cliffs are 435 million years older than the much younger lower slopes.
So how did a rock formation so old end up on top of the relatively young rock?
Thank the tectonic forces which compressed western North America, causing the final mountain building phase of North America. The massive forces caused folding, uplifting, faulting and thrusting, beginning some 75 million years ago.
Several faults were created (cracks through multiple rock formations) facilitating the thrusting of huge blocks of rock.
In the case of Mount Yamnuska, the McConnell thrust fault (see image below) allowed massive blocks containing rocks formations ranging from 510 million to 75 million years old to slide up and over adjacent blocks.
This resulted in older Cambrian rock to slide directly over the much younger Cretaceous rock. Subsequent and ongoing erosion of the rocks above resulted in the current shape and configuration of Mount Yamnuska.
The younger, softer sandstone eroded and crumbled under the weight of rock above, resulting in the steep slopes at the front of the mountain. The harder Cambrian rock retained its shape more successfully resulting in the shear upper cliffs. This harder Cambrian limestone makes for excellent climbing due to its stability.
Mount Yamnuska – Recreation
Mount Yamnuska is a very popular destination for hiking, scrambling and climbing.
The shear cliffs offer some 200 multi-pitch climbing routes with difficulties ranging from 5.5 (intermediate) to 5.14 (very difficult)
For adventurous hikers, there is a 9 kilometre (5.5 mile) loop Yamnuska hike, that takes you up one side of ‘Yam’, across the top of the cliff and down the other end of the mountain.
This Yamnuska trail is a difficult route due to some elevation exposure on portions of the trail. This trail is a mix between hiking and scrambling so knowledge and care need to be employed.
There are other Mount Yamnuska hike options less daunting that take you through the lower portion of the mountain which still deliver great views.
I am eager to hike this mountain again to re-experience the excitement, awesome views, and grandeur of Mount Yamnuska, the flat-faced mountain.
What mountain has always stuck in your memory?
Other geologically focused posts you may be interested in are: