It has happened to most of us drivers here in Jasper. One late winter or early spring day you’re driving down Highway 16 toward Hinton, only to reach Jasper Lake and be suddenly engulfed in a dust storm that throws your car around and pelts your windshield with silt.
The east part of Jasper National Park is dusty, and I don’t mean just a little. There have been drives when I can’t see farther than five metres in front of my car, and later notice my teeth are gritty from the silty particles that have snaked their way in through the vents. I’ve always thought of these episodes as “sand storms,” but I was wrong. They are “dust storms,” and there’s a difference.
Dr. Chris Hugenholtz studies dust. He’s a professor at the University of Lethbridge and the University of Calgary, and he’s just returned from New Mexico where he was working at White Sands National Monument. He has spent a great deal of time in the Canadian Prairies studying agricultural dust. But one of the most unique and naturally dusty landscapes he’s studied is found at Jasper Lake.
“Most people think of dust being an arid, desert-like phenomenon. But it’s present in a localized, unique area around Jasper.”
“Dust is pretty much anything smaller than fine sand,” Hugenholtz said.
Sand is heavier, and around here, stays close to the ground surface when blowing around.
“It gives you the prickly feeling on your legs, the ‘sandblasting,’ whereas the dust is the stuff that gets up much higher in the air, and can travel long distances.”
These are the dust storms we sometimes experience when we drive by Jasper Lake.
Jasper Lake is not a lake at all, but a seasonally filled reach of the Athabasca River. The shallow “lake” is formed when late spring and summer meltwater increase the volume and velocity of river water entering the basin. Water movement is slowed downstream by two big sand and silt accumulations formed where the Snake Indian and Rocky Rivers enter the Athabasca. As water movement slows, sand and fine particles that were collected upstream settle out.
But come fall, the water of Jasper Lake begins to drain away, reducing the flow to one or two river channels. Left behind is a sand flat approximately two by eight kilometres long. By winter it is completely dried out. Constant westerly winds accelerate as they are funnelled against the mountain sides, scouring the barren lake bottom.
One would think dust would become mobile more readily than sand, given the fact that it’s lighter. But it’s actually the movement of sand that initiates a dust storm.
“Once you get enough wind to mobilize larger particles like sand, they start hopping and skipping across the surface, kicking up the smaller particles that are wedged in the sand matrix,” said Hugenholtz.
This is similar to what happens when a child pours dry sand into buckets; as the sand is poured from one place to another, dust is released into the air.
At Jasper Lake the sand is too heavy to move very far, and ends up forming the sand dunes we see along the north side of the highway. But the dust is often carried several kilometres.
The rates of dust movement at Jasper Lake are some of the highest recorded to date in contemporary North America. During his study, Hugenholtz recorded thousands of tons of dust blowing across Jasper Lake.
If that seems like a lot (and it is), consider that dust storms occurred even more frequently thousands of years ago along the foothills and mountain boundary area. Hugenholtz said a lot of that dust accumulated near Hinton. “We know that into Hinton, and further east, there are [dust] deposits that have been very important for agriculture, because it has moisture-retaining capabilities.” You can see it along the roadside as you drive through.
Hugenholtz said studying Jasper Lake gives scientists a peek at what the end of the last ice age looked like 10,000 years ago.
“When the ice sheet was receding, we had major rivers, much larger than we have now. Those were [also] changing the water levels on a seasonal basis. It was colder, there were stronger temperature gradients driving stronger winds, so that means there was a lot more potential [for particles to become airborne]. Western Canada was much dustier at the end of the last ice age. Jasper Lake gives us an idea of what that may have been like.”
Hugenholtz said the global impacts of dust on climate are still debated in his field. But what we do know is that dust can have an impact at a regional or local scale, with some unexpected results.
For example, as Jasper Lake dust storms hit forests further east, the wind is absorbed by the trees, and the dust settles on the vegetation. “It turns out that some plants do well with a sprinkling of dust and slight rates of burial, such that it actually stimulates growth,” Hugenholtz said. He pointed to juniper as one species, in particular, that responds well to this kind of disturbance. “There’s definitely work to be done to try and understand why this is.”
In this way, dust could be viewed as a type of cyclical natural process, although, as Hugenholtz said: “It’s a smaller and slower process than an avalanche or fire, and more spread out over geologic time. But it might be doing some really neat things in terms of ecology in [the] area.”
Hugenholtz hopes to be back at Jasper Lake this summer to do more measurements. With the same passion a paleontologist uses to uncover the past in the bones of dinosaurs, Hugenholtz will take finer scale measurements of dust and sand in an effort to better understand the processes that shaped this area, and the rest of Western Canada.
I’ll remember that the next time I drive through. The dust storm that envelops me is actually history in the making.