Volcano Valley

Unbeknownst to the millions who pass through them every year, the mountains of southwestern British Columbia form an active volcanic region thousands of years in the making that could be on the brink of cataclysmic change.

- Andrew Findlay

IN JULY 2016, helicopter pilot Hannibal Preto was flying above Mount Meager, about 40 kilometres north up the Lillooet River valley from Pemberton, B.C., when he caught the whiff of rotten eggs.

A few minutes later, he took his passenger, a wildlife biologist conducting a mountain goat survey, higher up the peak, where Preto spotted vapour emanating from a hole in a glacier. “Combined with the sulphurous smell from earlier,” says Preto, “it was clear to me that we were looking at fumaroles.”

For Preto, who is a graduate of the University of Victoria’s geology and earth sciences program, it was an exciting discovery — or rather rediscovery. Anecdotal reports dating back to the 1930s from mountaineers and other adventurers had also noted the telltale sulphurous rotten-egg smell in the vicinity. Preto’s sighting was a reminder that although these mountains appear docile today, the forces of volcanism that shaped this rugged corner of southwestern British Columbia are still very much alive.

A YEAR AFTER Preto’s sighting, I’m perched on the brink of Keyhole Falls, where the Lillooet River squeezes through a slot canyon that’s barely two arm’s-lengths wide and over a 100-metre precipice into a horseshoe-shaped canyon. Across the river, avalanche paths plunge from the 2,680-metre massif of Mount Meager, one of the northernmost in a chain of volcanoes known as the Garibaldi Volcanic Belt, which itself is the northernmost extension of the Cascade volcanic arc that includes prominent volcanoes in the United States such as mounts Baker, St. Helens, Rainier, Adams and Shasta. Somewhere high above me, pungent gas escapes through a crack in the ice — the exhalations of a sleeping giant.