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Next time you go up the Peak Chair or the 7th Heaven Express pause long enough between runs to pick out the volcanoes. Six of them are visible from either mountain: The Black Tusk, Mount Garibaldi, Mount Fee, Mount Cayley, Powder Mountain, and Ring Mountain. And if you happen to arrive at the top on one of those glorious calm days when the valley is filled with fog and only the tops of the mountains rise into sunshine above the brilliant white cloud layer, let your imagination turn the fog to ice and you will have an image of how the world looked when many of the Garibaldi Belt volcanoes were active.
Known as the Fraser Glaciation, the period between 24,000 and 10,000 years ago began with a drop in global temperature that triggered the growth of alpine glaciers. These rapidly expanded into valley and piedmont glaciers that ultimately coalesced into the Cordilleran Ice Sheet which, at its maximum about 14,000 years ago, covered most of British Columbia. At that time huge valley glaciers, flowing south out of the main ice sheet past Whistler/Blackcomb and into Howe Sound, extended as far south as central Washington State. And as Bill Mathews began to unravel the story of Mount Garibaldi he discovered an amazing correlation between the volcanic and glacial history.
From the top of Whistler only the uppermost dome of Mount Garibaldi is visible against the southern horizon. The best place to get an overall view is from the top of Black Tusk. It's a bit of a scramble up a chimney on the back side but you not only get the view, the climb gives you bragging rights that are guaranteed to impress visitors who see only the steep, edge-on profile of the Tusk from Whistler or Blackcomb. In fact, the chimney has been climbed by so many people that the route is worn smooth not even any loose rocks to worry about but beware of tourists in running shoes.
About 170,000 years ago the Black Tusk was an active volcano. It once had the conical shape of a miniature Fuji but centuries of erosion, including the ravages of the Fraser Glaciation, have stripped away the outer pyroclastic cone of loose bombs, blocks, and ash, leaving only the solid plug-dome of lava that once filled the central conduit and now forms the narrow summit spire. It was already deeply eroded when Garibaldi burst onto the scene.