This was an August day hike to explore, look for caribou and wildlife, and identify wildflowers. I was with a group from Bathurst Inlet Lodge, hiking in the vicinity of Gordon Bay on the east side of Bathurst Inlet.
We topped a little rise and an amazing sight stretched before us: a white mass filling a small river valley between gravelly hills. The land all around was green, but the river valley was a brilliant white. I’d seen these before from the air, but this was my first up close encounter with an amazing arctic structure – aufeis, or ‘overflow ice’. It was about four metres thick, layered, and it almost glowed. Certainly not snow!
Sliding down a bank, we entered a series of channels cut through the ice. The ground was littered with caribou and arctic hare bones, and piles of wolf scats. We scanned the surrounding hillsides, but nothing moved except a couple ravens. The narrow ice channels, some two to four metres deep, and two metres wide, were completely clear of ice and the ground had a thin layer of wet sedges and mosses. We found more wolf scats, tracks, and more bones. These were small, bones of caribou calves, hare bones, a few goose bones, and the tiny scats of wolf pups. It dawned on me – this was a wolf daycare! One or two adult wolves likely stood guard at the edge of the aufeis, and kept the cubs corralled in the air-conditioned channels, while the rest of the pack hunted. No wolves appeared as we examined the sheer walls of the channels. Made slick by daily warm temperatures, the walls still showed multiple layers, some marked with dust incorporated in the ice. It was obvious this ice was laid down in layers, one flowing over another, then freezing to create a hard, somewhat arched, structure.
On summer flights over taiga and tundra, you often see aufeis, visible from a great altitude. It might resemble a glacier, but it is not multiyear ice. These isolated white patches have an irregular shape with abrupt edges that more or less follow a valley. They are sometimes furrowed with deep channels.
Aufeis forms when there is a flow of groundwater through saturated gravels at the edge of a stream valley, or by flow from under the ice of a stream, usually from a lake higher up. In winter, water overflows existing ice in the streambed, and freezes, then more overflows, repeating, as layers build up. Occasionally, the ice builds from below as well. Hydrostatic pressure can force water to the surface, creating mounded structures of smooth, very hard ice.
I remember an area of aufeis on the edge of Bathurst Inlet, where water flows into a lake we call Emerald Lake. We visited this in May on a spring program, traveling by snowmobile along the old traditional trail to the Mara River. We came upon a huge dome of ice at the edge of the lake. It was easily five metres high, the colour, a bright blue. Ancient stone inuksuit lined the high bank above the ice dome, lending a surreal feel to the landscape.
Because the ice chills the air, and heavier cold air pools in the stream valleys, aufeis remains for much of the summer, creating its own microclimate. And around the ice, there is an aufeis ‘barrens’, sometimes referred to as an arctic oasis. These are similar to the plant communities that develop where snowbanks remain long on the ground, melting back gradually in summer. Water is plentiful, due to the melting ice. So the plants that survive here are ones that cannot compete out on the open tundra, that need a constant source of moisture, and that can bloom and set seed in a growing season about a third of the length of the summer season away from the ice.
Plants like pygmy buttercup, mountain sorrel, least willow, white arctic heather, moss heather, blue mountain heather, bog laurel, and small sedges manage to hang on here. Tunnels of meadow voles wind through the edges, and the globular nests of lemmings and voles reveal where these small mammals spend the winter. In summer, caribou and grizzlies often bed down on top of the ice as the cooling effect discourages botflies and mosquitoes, and provides relief from the noonday heat. The ground under aufeis also remains slightly warmer in winter than the surrounding land, and allows many microorganisms and small invertebrates to survive.
Once aufeis forms, it tends to form again year after year. But examples are scattered and difficult to get to, if you don’t have a helicopter or aren’t canoeing a relatively small river. It is almost inevitable that the quantity of aufeis will diminish with climate change, while the central barrenlands continue to warm and summers lengthen.
Aufeis can be dangerous if it has formed where a river runs into ice channels and then under the ice. If you are canoeing and see aufeis ahead, beach your canoe and walk ahead along the edge of the ice to determine if the channels persist through the aufeis or if they peter out. If the water flows into under-ice channels, it can suck a canoe under the ice, and that can be deadly.
Sometimes, aufeis is in an area of major flow during the spring freshet and disappears relatively quickly. One year, aufeis formed on the Meliadine River near Rankin Inlet where a new bridge constricted the flow of the river. The dome of ice built up over the winter, and neatly dammed the river. The spring melt flooded the river valley to a depth of about two metres, washing out the road and culvert, and threatening the bridge. Luckily, warm weather intervened; the current cut through the aufeis, and the problem was solved, but it was a spectacular flood while it lasted.
At Point Lake, near Peterson’s Point Lake Lodge, there is an area of aufeis readily accessible via a boat ride and hiking. Guests hike over a sandy esker and undulating terrain with stunning views, descending into a valley via a steep ridge to the gleaming white length of ice. They can explore its channels and admire the tiny plants of the aufeis barrens while watching for grazing caribou, soaring rough-legged hawks, and other wildlife, including (perhaps) wolves babysitting pups.
And did we find wolf pups at Gordon Lake? Yes, we found them, and spent four hours watching them play and observing as the adult wolves returned with a snack of siksik (arctic ground squirrel) for the pups. In the end, we sneaked away, leaving them to their wrestling beside the aufeis, with the sinking sun in the north casting a golden glow over ice and pups.