Park holds a rare piece of geology
Terry Halifax
Northern News Services
Lake Athabasca (Nov 20/00) - Just below the 60th parallel, the boreal forest is yielding to a bizarre geological formation unique to the world.
Giant sand dunes have blown up from the banks of Lake Athabasca and surrounding river systems to form a desert in the midst of jackpine and spruce.
The Athabasca Plain is home to the Athabasca Sand Dunes Provincial Wilderness Park -- about 2,000 square kilometers of wind-swept sand dunes, river systems and boreal forest.
Photographers and authors Robin and Arlene Karpan visited the dunes four times to gather information and images for their book Northern Sandscapes, Exploring Saskatchewan's Athabasca Sand Dunes.
Robin said the sight of the dunes is a stark contrast to anything he's seen.
"It's unlike anywhere, period," Karpan said. "It's considered the largest area of dunes in Canada and depending on how you measure, it could be the largest in North America."
The wind is slowly taking the sands southeast, leaving a desolate, dead forest.
"It's slow, but they are advancing," Karpan said. "It goes with the prevailing north-westerly winds. There are a lot of places where you get the edge of the dune and you can see how it's covering the forest floor.
"You'll have green vegetation and then this very sharp line where the edge of the dune face is moving in," he explained.
Changing landscape
As the dunes advance, wind uncovers trees that were buried centuries ago.
"It looks almost like petrified wood," Karpan said. "It's not really petrified, it's just very dry and desiccated and very ghostly looking."
The William River is the water course in the park and Karpan said it serves as a boundary which accentuates the contrasting landscape.
"For a 25 kilometre stretch it's like a ribbon between two totally different worlds," he said.
"On the east shore is fairly typical jackpine forest that you see throughout the North and on the west are walls of sand that come right to the water's edge."
The prevailing winds keep the dunes moving toward the river and the William washes the sand downstream into light and dark brown braids which Karpan describes look like "butterscotch pudding and whipped cream."
"It doesn't even look like a river bottom, because it's so bizarre," he said.
Peter Jonker is the program director for Environment Science and Technology programs at the University of Saskatchewan. He is completing a comprehensive manual on the unique dunes.
"They are the most extensive dunes in the world North of 55 degrees," Jonker said. "The largest dunes are about 100 feet high."
He has led about a dozen tours into the dunes and people are always amazed by the sight of the sand in the sub arctic.
"There is enormous contrast between the starkness of the sandscapes and the lushness of the surrounding forest and river valleys," Jonker said.
Another peculiar feature are areas of "gravel pavements" created when the wind swept away sand and left rock formations that look like a cobblestone street.
"They are exactly one stone thick, you can dig your hand underneath and it's just sand again," he said.
He describes the enormous underlying sandstone as a "thin lens" which covers the ancient Canadian Shield beneath.
"It extends from the north shore of Lake Athabasca, south to Cree Lake, east to Wallaston Lake and west to the Alberta border," he said. "All of that was blowing sand at one point."
Dunes will disappear
The forest acts as a "snow fence" and the dunes can only blow one way. Over thousands of years, the dunes will eventually disappear, Jonkers said.
Geologist Dr. Walter Kupsch, of the University of Saskatchewan, said the formation of the dunes began when the Athabasca region was entirely under water.
Kupsch said the sandstone was formed around 700 million years ago when the area was covered by water and marine sand settled on the bedrock.
The massive lake stretched 1,000 kilometers from Great Bear Lake, south to what is now Great Slave and still farther south to Lake Athabasca.
"It used to be a basin and sandstone was deposited on top of the bedrock by the sea," Kupsch said. "Sand was deposited on top of the Precambrian rocks beneath the sea."
