Nothing cuts through the quiet serenity of a dog team's headlong plunge through the Canadian plains as the sound of steel bearings grinding to silvery bits.

Dave Halsey has heard that sound twice. It's about all he can take.

Halsey's dogs have been towing a toboggan full of food and gear along a gravel road 100 miles west of Flin Flon, Manitoba. He and partner Pete Souchuk, trekking west to east across Canada for the fun of it, have lately been running alongside the toboggan and listening for the sound of wheels giving up.

Wheels?

"It's really depressing," said Halsey, who left home in McLean, Va., last spring to make this voyage. "We wanted to go on the old trapper trails, but there aren't any. We even flew over the route in a private plane trying to find a passage. There's none there."

So they went to the road. First they tried the shoulder and watched helplessly as the dogs floundered in the deep, plowed snow. Then they brought their first pair of wheels and moved to the gravel. They lasted half a day.

Souchuk hitchhiked ahead and ordered a second set of fancier wheels. They lasted 17 miles.

And now Halsey and Souchuk, Canada wildnerness explorers, are walking to Flin Flon on the road. When they get there they'll rent or borrow a truck, drive back into the wilderness and collect their dog team, drive back to Flin Flon and continue with the mission.

The two young Americans have found first hand the state of the dog-sledding art in 1978. Like the horse before it, the bighearted sled dog has been outflanked and outrun by fossil fuel and the internal combustion engine.

"Let's face it," said a native Manitoban who has watched the decline of sled dogs, "you don't have to feed a snowmobile all summer." And as dogsleds are abandoned, so are dogsled trails.

Halsey and Souchuk hope to get back to smooth sledding once they pass Flin Flon. Their schedule has them traveling south along Lake Winnipeg through March and they hope to be near Lake of the Woods at the Manitoba/Ontario border by spring thaw. They will continue across Ontario and Quebec by canoe and hope to arrive at their final destination, Tadoussac, Quebec, on the St. Lawrence River, before the fall freeze.