Thursday, September 19, 2019

Travels in Cascadia: The Southernmost Fjord in Western North America: Howe's that Sound?

Our journey through the Pacific Northwest and British Columbia continued. We had spent several days on Vancouver Island, exploring Goldstream Provincial Park, Mt. Douglas and the Mutton Rocks of Victoria, Sitting Woman Falls, and the gabbro oceanic crust of East Sooke Park. It was now time to head back to the mainland and our goal was to explore the geologic environments of Howe Sound, the southernmost glacial fjord in western North America.

We would spend several days looking at this fascinating geological environment. To get there we would need to take a ferry from Nanaimo on Vancouver Island back to the mainland at Horseshoe Bay inside Howe Sound. We just missed an earlier ferry, so we cooled our heels for a couple of hours in the tourist traps at the ferry terminal. Our attention was distracted by a pair of otters hiding out in the shade beneath the ferry building.

After a few hours we were underway, leaving behind the fairly muted glacial topography of Vancouver Island, and heading towards the decidedly more mountainous country of the mainland. The main contrast was that glacial ice sheets covered Vancouver Island, but the mountains rose above the glaciers on the mainland. We could see the city of Vancouver off to the south.

As we scanned the horizon from the upper deck of the ferry, we could see that we were still definitely in the land of volcanoes. Off to the east we could just make out the lower flanks of Mt. Garibaldi, one of the northernmost of the Cascades Volcanoes. Garibaldi is one of the most unusual of the Cascades because a large portion of the edifice was erupted onto a glacier. When the glacier melted away at the end of the ice age, the flank of the volcano collapsed into the adjacent valley in a series of huge debris flows.
Mt. Garibaldi, with Howe Sound in the foreground

The clouds were playing hide and seek, and mostly 'hide' with the summit of Mt. Baker off to the south in Washington. The glacier-covered peak of Mt. Baker is geologically young, and the mountain seemed on the verge of erupting back in 1975, but it fizzled out to the disappointment of geologists and to the relief of everyone else.
Mt. Baker, partly hidden by clouds, from Howe Sound

My favorite sight from the ferry ride was of the Black Tusk or t'ak't'ak mu'yin tl'a in7in'a'xe7en in the language of the Squamish people, who considered the strangely shaped peak to be the landing place of the Thunderbird, a principle figure in First Nations mythology. In geological terms, the mountain is a deeply eroded stratovolcano, once like Mt. Baker or Mt. Hood, but now a spikey remnant of the original cone
The Black Tusk from Howe Sound

As noted before, Howe Sound is a glacial fjord, a deep bay with steep flanks that was carved by glaciers. It is a bit difficult to pick out the entrance from the Strait of Georgia because it includes several islands. The sound is 26 miles long, ending at the town of Squamish at the upper end. The urban center of Vancouver is just south of Howe Sound where there is more level ground.

The sound is full of geological delights. We would spend the next four days in the immediate vicinity. That's where we'll pick up the story next time.

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