Friday, August 21, 2015

Vagabonding on Dangerous Ground: Landing Place of the Thunderbird and the Grimy One, the Volcanoes of British Columbia

Nch'kay (Mt. Garibaldi) near Squamish, B.C.  Photo by Mrs. Geotripper
t'ak't'ak mu'yin tl'a in7in'a'xe7en and Nch'kay ("Landing Place of the Thunderbird" and "Grimy One") are the Squamish names for two of the most striking volcanoes in British Columbia. Much more recent colonizers refer to the mountains as Black Tusk and Mt. Garibaldi. I prefer the older names; we should name buildings after people, not mountains. They stand at the far north end of the Cascades Volcanic Arc, and although not as well known as their southern neighbors (at least to those of us in the lower 48), they are a potential threat. Mt. Garibaldi, in particular, is seismically active, although it has not had an eruption in about 10,000 years. Debris avalanches are an ever-present problem, however.
Garibaldi is 2,678 m (8,786 ft) in height, and is one of the more unique volcanoes of the Cascades. Much of the mountain erupted on top of a glacial ice sheet, so that when the glaciers melted back, around half of the edifice collapsed in a series of debris avalanches and mudflows. Mass wasting events have continued into modern times, and some of the slopes are considered dangerous enough to limit development in the areas affected. The oldest lava flows date to around 250,000 years ago and are composed of mostly silica-rich lavas such as dacite and rhyolite. The mountain doesn't show much evidence of more violent ash eruptions.
I was incredibly disappointed when clouds obscured our view of Garibaldi on our previous trip through the area, so our trip a few weeks ago was especially gratifying. As it turned out, we took just a few pictures from a pullout with lots of overhead wires, thinking we would get more the next day when we had a few more hours to spare. As luck would have it, the next day was more cloudy...such a surprise in the Pacific Northwest! These were our only pictures of the peak.

The story was very nearly the same with t'ak't'ak mu'yin tl'a in7in'a'xe7en (Black Tusk). We got some distant shots of the peak from the glacial fjord of Howe Sound. The next day we snapped a few pictures as clouds chased around the uniquely shaped summit. As noted in the title of the blog, the name refers to the Landing Place of the Thunderbird. The black color is said to result from the constant lightning strikes associated with the legendary bird.
t'ak't'ak mu'yin tl'a in7in'a'xe7en (Black Tusk), from the Whistler Olympic Venue. Photo by Mrs. Geotripper
The Tusk is 2,319 m (7,608 ft) and much older than Garibaldi. The main peak developed from eruptions around 1.1-1.3 million years ago, forming a stratovolcano. During a subsequent lull, most of the mountain eroded away. The last eruption took place around 170,000 years ago, so the peak is most likely extinct. Other cones in the area have been active in the last few tens of thousands of years.

I was extremely happy to have seen the volcanoes, but I was equally impressed with the other scenery as well. We spent a night in Whistler, and then did something significant: we turned around. The vagabonders were now starting for home, but there was plenty more to see. More posts to come!

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