A hole in the landscape

by Jon and Leif Nelson

A father and son team unravel the mysterious origins of Devil’s Crater and discover a portal to the past.

My first glimpse of Devil’s Crater took my breath away. I was shooting aerial photographs of outpost cabins for a local outfitter when the pilot and I decided to take a detour to look at an unusually shaped lake off in the distance. In a few minutes, the small, almost perfectly circular lake was below us. Surrounded by towering cliffs, it lay in the midst of a gently undulating topography filled with the bogs, creeks, small lakes and boreal forest that are typical of northwestern Ontario. In an otherwise relatively flat landscape, the crater’s presence, along with the kilometre-long canyon just southeast of it, was a mystery.

I knew immediately that I had to see this remarkable formation up close. My son Leif, a graduate student at the University of Waterloo, and my good friend Al Maddox, a retired teacher and experienced canoeist, were eager to accompany me. Devil’s Crater is located some 150 kilometres north of Thunder Bay, Ontario. There are no roads within 20 kilometres of the crater and canyon, so we decided to fly in and land on a small nearby lake connected to the canyon via a narrow creek.

In the last days of June, we found ourselves crowded into a single canoe, heading down the creek toward the crater. Before long, however, a combination of shallow water and boulders made further progress impossible. Despite much searching, we could not find a portage, although we knew that two other groups from Thunder Bay had reached the crater by this route during the last few years. (The crater is also part of a trapline for a member of the Gull Bay First Nation on Lake Nipigon. First Nations communities in the area have a long history of visiting the crater.) We decided to make a portage using a small chainsaw we had brought with us “just in case.”

We had a beautiful paddle up the canyon. The day was cool and sunny, and there was enough wind to keep the bugs to minimum. Along the canyon shoreline were large rocks and scree slopes at the base of the cliffs. In other spots, the majestic cliffs soared directly out of the dark waters, in which we could see the shimmering reflections of our surroundings. We were eager to fish as we had heard that brook trout might be present.

We managed to catch a northern pike but no trout.

A large amount of scree coming down from both sides of the canyon forms a plug across the narrow opening between the canyon and the crater.We made our campsite along the edge of a grassy area through which the narrow creek coming out of the crater meanders. Our spot was small and uneven; nevertheless we pitched our tent on one of the few dry openings in preparation for a two-night stay.

We were hoping to portage along the base of the scree and reach the crater with relative ease. As the designated photographer, I went ahead and climbed partway up the side of the crater. Leif and Al had the much harder task of hauling the canoe over a great jumble of boulders while weaving it through trees and shrubs – so much for the “relative ease” plan. From my perch I could see two small waterfalls cascading down the cliffs that formed the far wall of the crater – the only visible sources of water entering Devil’s Crater.

Despite what the lake’s name would suggest, a meteorite did not create Devil’s Crater. The impressive force responsible for the crater, and the canyon stretching out below it,was the combination of the retreat of the Laurentide Ice Sheet and the overflow of glacial meltwater from Lake Agassiz, which was then located just west of the crater. The flow from the two small waterfalls that now enter the canyon is a mere fraction of the torrent that carved this feature into the landscape more than 9,000 years ago. Thousands of years of erosion have also softened the crater and canyon. Falling rock combined with lichen growth make it difficult to determine just how much water must have surged through the kilometre-long canyon when Lake Agassiz overflowed. The events that produced Devil’s Crater not only altered the landscape significantly, but may well have been the catalyst for climate change and have influenced the migratory patterns of the first humans who lived in this area.

Approximately 18,000 years ago, the air temperatures of the earth began to rise as the planet emerged from the most recent ice age. Massive continental glaciers that had blanketed most of central North America, including the Laurentide Ice Sheet,were slowly retreating. The water pouring out from the melting Laurentide Ice Sheet – which covered much of what is now Ontario,Manitoba and parts of Quebec, Saskatchewan, Nunavut, Minnesota and North Dakota – produced enormous lakes. One such lake was Lake Agassiz, which formed to the south of the retreating glacier.

Lake Agassiz extended over more than 1.5 million square kilometres, an area larger than all the present

Great Lakes combined. As the lake slowly shifted northward following the retreat of the massive glacier, its shape, size and position changed significantly. Over a 5,000-year period, various outlets routed the lake water in three different directions: south through what is now the Mississippi River Valley to the Gulf of Mexico, east through the Great Lakes and what is now the St. Lawrence River to the Atlantic Ocean, and finally north to Hudson Bay and the Arctic Ocean.

Changes in the direction of the outflow of Lake Agassiz would have significant consequences. It has been generally accepted that the eastern overflow of Lake Agassiz initiated some 11,000 years ago resulted in a tremendous amount of glacial meltwater surging through the Great Lakes basins into the North Atlantic Ocean. The influx of fresh water essentially diverted ocean currents in the North Atlantic, resulting in a significant cooling of the climate in North America and Europe. This 1,000-year cooling period, referred to as the Younger Dryas, is characterized by the lowering of average air temperatures around the North Atlantic at a time when global temperatures were increasing.

Phil Kor, the senior conservation geologist for Ontario Parks who has researched this topic, says, “Although recent research is challenging this theory, as alternate routing of the meltwater from glacial Lake Agassiz is being considered, the influx of an enormous volume of fresh water into the North Atlantic from the Great Lakes basins still seems to be the best explanation for changing ocean currents and the climate in North America and northern Europe.”

As Lake Agassiz continued its northward shift, the land behind it slowly rebounded as the great weight of the glacier withdrew. Water from Lake Agassiz flowed south when ice occupied the Superior basin. Then it flowed again to the east, this time through Lake Nipigon and on to Lake Superior and the North Atlantic Ocean. Large volumes of water flowed through channels that today are shallow streams and creeks.

As the glacier receded, new outlets formed in a northerly pattern. The water ran through this new area with such tremendous force that it carved Devil’s Crater, along with the canyon southeast of it, out of the bedrock of the Canadian Shield. In creating this deep gash in the landscape, the rushing water worked in tandem with local geology. The crater and the canyon probably began as a fault in the bedrock. The immense overflow eroded the bedrock along the fault to create the crater and canyon.

Eventually, the continued retreat of the glacier and the rebounding land surface behind it opened up new outlets north of Devil’s Crater. The outflow through Devil’s Crater would have lasted only a short time, anywhere from a few years to a couple of hundred years. James Teller, professor of geology at the University of Manitoba and a leading researcher on Lake Agassiz overflows, has written that the spillways from the Lake Agassiz overflow formed “spectacular breaks in slope. These ‘knickpoints’ form 50- to 100-metre-deep plunge basins in the Lake Agassiz spillways.” The most spectacular example of these plunge basins is Devil’s Crater.

From inside the crater, the view is incredible. Two-thirds of the crater’s edge is a curved wall of dramatic, lichen-encrusted cliffs that rise more than 70 metres directly out of the water. When seen from a canoe on the lake, the cliff walls seem even higher because the lake is only about 200 metres in diameter. The remaining portion of the crater’s edge is a steep slope composed primarily of large boulders. Al noted that, from some locations, there didn’t seem to be any way out other than scaling the cliffs. Near the middle of the lake,we tied a rock on the end of a rope and lowered it to the bottom in an attempt to estimate the depth of the water. We were astounded to find that our primitive measuring device indicated that this tiny lake is approximately 70 metres deep.

When travelling into and out of the crater, we were paddling near the bottom of a spillway formed more than 9,000 years ago. What is now a canyon was once filled with water that moved with enough force to enlarge a crack in the bedrock and form a chasm. This area, whch is now a mass of car-sized boulders,was once submerged beneath at least 50 metres of rushing water.Today, white and red pine trees grow along the canyon and near the edge of Devil’s Crater.Three arctic alpine plants, Nahanni oak fern, smooth woodsia and showy locoweed, grow along the shaded cliffs nearby.

Researchers, primarily Teller and associates, have found that the terrific amount of water that once tore through this area left behind remnants of riverbeds, broad, flat deposits of sand and gravel, and giant boulders at various locations between Lake Agassiz and Lake Nipigon. In recognition of the significance of these areas, the Pantagruel Creek Provincial Nature Reserve and the Ottertooth Conservation Reserve were established. Ottertooth Canyon and Mink Bridge Portage Falls on the Kopka River are dramatic remnants of the glacial spillways.

Lichens, herbs, grasses and shrubs quickly populated the newly exposed land. Large, cold-adapted grazing animals, such as woolly mammoths,muskox and barren-ground caribou, thrived. So did sabre-toothed tigers and “dire”wolves, which grew to one and a half times the size of timber wolves. The most intimidating predator of all, human beings, may also have been present. Paleoindians, the first people known to have inhabited this region, probably followed the large mammals in their northerly migration.

However, by the time Lake Agassiz overflowed into Devil’s Crater, the woolly mammoths, sabre-toothed tigers and dire wolves were extinct, but caribou continued to be a main source of food for Paleoindians. In 1957, a caribou antler recovered from the bottom of Steep Rock Lake near Atikokan, Ontario,was determined, through carbon dating, to be nearly 10,000 years old.William Ross, a retired regional archaeologist for the Ministry of Tourism, Culture and Recreation for the Thunder Bay region who is regarded as a leading authority on the archaeology of northwestern Ontario, told us that “there is a strong possibility that Palaeoindians were witnesses to the dramatic overflow of Lake Agassiz.The water surging down the east side of Lake Agassiz may have prevented these early peoples from expanding northward until the waters subsided enough that a crossing to the north could be safely made.”

Floating in our canoe on the small, placid lake inside the crater, we were in awe of what occurred here at the end of the last ice age. The crater’s two small waterfalls are reminders that just over 9,000 years ago, an outpouring of water draining a lake that stretched all the way to Saskatchewan careened and swirled through here with devastating power to form Devil’s Crater and the canyon below it. These formations are portals to the past. They remind us how, in an instant of geological time, a piece of Ontario’s terrain was dramatically altered.

BUY THIS ISSUE!

---

Jon Nelson, a part-time archaeologist, is a former Quetico Provincial Park ranger who recently retired from teaching at Confederation College in Thunder Bay, Ontario. Images and articles of northwestern Ontario can be seen on his website, www.jon-nelson.com.

Leif Nelson is a graduate student in the Earth Sciences Department at the University of Waterloo working on a master’s degree in hydrogeology.