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Naturalists speaker talks of cooler time in B.C.

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B.C's Ice Age leaves its footprint

With only a handful of glaciers dotting the nearby landscape these days it's hard to imagine there was a sheet of mile-high ice covering Whistler 15,000 years ago.

Yet, for the past two million years there have been huge ice sheets waxing and waning over the Northern Hemisphere - a time period collectively known as the Ice Age.

"We are smack dab in the middle of that period," said Dr. John Clague, professor of earth sciences at Simon Fraser University.

Clague cooled things down for the crowd at Millennium Place last Thursday night with his presentation on "A Time When Glaciers Ruled - The Ice Ages in B.C." hosted by the Whistler Naturalists.

Among other things, Clague talked about the icy footprint the glaciers had on the surrounding area and the more obvious physical features they left behind.

"We have such a profound signature of glaciation in B.C.," he said.

Clague took the audience on a slideshow journey beginning 27,000 years ago.

That period of time marked the beginning of the last major onset of ice in B.C. and subsequently, geologists get the best information about the Ice Age from this period.

It was around this time the ice in the mountain ranges began to expand.

Roughly 5,000 years later glaciers from different mountain ranges started to meet and merge into each other.

By 15,000 years ago they had merged together to form a complex ice sheet with flow moving in different directions and extending across Vancouver Island and into the Pacific Ocean.

In fact, the whole country except northern Yukon, which does not have enough moisture in the air to sustain an ice field, was covered in ice at this time.

This was the peak of the last ice age.

Then the glaciers began to retreat and 5,000 years later they had disappeared altogether. In geological time, this is considered a fairly fast retreat.

"This requires a radical change in climate," said Clague.

He said the change in climate was probably related to changes in the earth’s orbital path or to some complex interplay between the oceans and the atmosphere.

But currently there is no way of knowing for sure what caused the rapid retreat.

As the ice began to decay all of present-day Vancouver was covered in water.

The weight of the ice sheet had pushed the land down, depressing the surface by about 500 metres, causing it to be submerged by the sea.

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