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NatureSpeak Articles

On A Clear Day, 14,000 Years Ago

Skiing above the valley fog – or could it be glacier ice? Photo: Paul Morrison courtesy of Whistler-Blackcomb

It started off as just another dark dank late winter day with fog in the valley so thick you could get lost in the parking lot. The kind of day when cabin fever skews your ability to make rational decisions and you head up the mountain regardless.

My trip up the lifts was like being encased in a damp grey cocoon so tiny that the cable disappeared into the gloom only a few feet ahead of my chair. Then suddenly, just below tower 19 on the 7th Heaven Express, the grey turns to blinding light and seconds later I am suspended above a vast expanse of white cloud glistening under a brilliant blue sky.

It’s a magical experience that evokes comparisons to whipped cream, or cotton batting or, if you are a geologist, to glacier ice. For me it’s like stepping out of a time machine into the world of 14,000 years ago when the Cordilleran Ice Sheet was at a maximum.

A small tweak of the imagination and peaks projecting above the cloud layer become nunatacks, islands of rock surrounded by glacier ice that once filled the local valleys up to an elevation of over 2000 metres. With a little more imagination, I can visualize the myriad of moraines winding like multi-land highways across the white surface.

Known as the Fraser Glaciation, the period between 24,000 and 10,000 years ago began with a sudden drop in global temperature that triggered the growth of alpine glaciers. These rapidly expanded into the 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.

Much of the scenery we now enjoy in Sea to Sky country was shaped in both large and small ways by the Fraser Glaciation. The broad U-shaped valleys of the Cheakamus and Squamish Rivers and the steep-sided, overdeepened fjord of Howe Sound are all products of glacial erosion. On a smaller scale almost any natural outcropping of rock along the corridor bears the scars of glacial souring in the form of grooves, fluting, and striae. And higher on the slopes, near the upper limit of glaciation, the ground is strewn with erratics, rocks plucked from some distant mountain, carried on the surface of a glacier, and finally left stranded in a new location tens or hundreds of kilometres from their source.

My trip down to the valley was not a memorable skiing experience. The fog bore no illusions of being anything but fog, but the memory of that view from the top and my brief trip back in time made the day.

Written by: Jack Souther

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