In the foggy mist, on the beaches of Lake Superior, an ancient people built their temporary shelters, rearranging the cobbles to form oval pits with their entrances sensibly placed on the landward side, facing away from impending storms. These aged structures, named “Pukaskwa Pits,” survive on the lichen-covered beaches that now lie well above the sand, pebbles and cobbles that edge the lake today. The people of the pits, however, are a mystery, any artifacts they left behind long lost among the cobbles. But the pits keep their story alive, offering us a tantalizing glimpse of the richly layered history that enfolds the greatest of the Great Lakes.
This Ontario Ecotour begins at the historic boundary waters of Pigeon River on the border between Canada and the United States. The route skirts the Canadian shore of the lake until it reaches the base of the Gros Cap cliffs near Sault Ste. Marie, where Superior’s waters flow into St. Marys River as it tumbles over red sandstone steps into Lake Huron.
The history of the landscape travelled by this Ecotour route started three billion years ago in the Precambrian Age, with the forming of a barren land of rugged black rock and dull grey dust, borne from numerous violently erupting volcanoes. For millions of years rain and erosion deposited sediments on deserts and in lakes and oceans, creating the land’s first sedimentary rock. Fissures, tapped into the Earth’s crust, turned into conduits for thick flows of red-hot magma. The magma intruded the older rock and formed large granite batholiths — the signature rock of the Precambrian Shield. Magma that flows to the Earth’s surface is called “lava.” Earthquakes ruptured the crust and pressures deformed, folded and faulted the rock. For added effect, while this violent land-building progressed, meteorites regularly smashed into the planet. Like a cake mix, some rocks were partially melted again by new intrusions of magma and altered, or metamorphosed, as geologists call this kind of transformation. The Precambrian, the oldest rocks on Earth, date from three billion to 570 million years ago. Precambrian rock underlies the entire course of our route from Pigeon River to Sault Ste. Marie.
Midcontinental Rift
 It took a continent-splitting event to create many of the spectacular cliffs and canyons of northwestern Ontario, and to form the mineral-rich basalt and valued sandstones that you will see nearer to Sault Ste. Marie. This key Ecotour event occurred 1.09 to 1.11 billion years ago when enormous tectonic forces ripped apart ancient North America, creating a 2,000-kilometre trough known as the Midcontinental Rift. The rift extends under Lake Superior and through fractures, faults and deformation measures up to 30 kilometres deep; it is the deepest known rift in the world. Volcanoes spewed more than a million cubic kilometres of lava basalt into the rift, forming one of the largest basalt deposits in the world, some of which we will see along the route. A major river system deposited sediments into the rift: sediments that ended up forming the famous Jacobsville sandstone that was used in the construction of many stone buildings in Sault Ste. Marie. But perhaps the most prominent result of the Midcontinental Rift was the formation of magnificent mesas (flat-topped, steep-sided hills), cuestas (flat-topped hills with one steep and one gentle side) and canyons — the landscape trademarks of northwestern Ontario. Mount McKay, the Sleeping Giant, Pie Island and the Ouimet Canyon are but a few examples of the rift’s legacy that are visible on this Ecotour.
Earliest Inhabitants
 Just 20,000 years ago, Ontario was buried in ice. Five thousand years later, the glaciers began to melt and finally, by 10,000 years ago, the Ecotour area was glacier-free. With the retreat of the ice, habitation by the Palaeo-Indians was not far behind. During this period, most of Manitoba was covered by glacial Lake Agassiz, and glacial Lake Minong was the name of ancient Lake Superior. The melting ice created new drainage channels and the Lake Superior basin changed: Water levels receded and lake beaches were left high and dry above today’s shoreline. We will see these ancient beaches of gravel, sand and cobbles at several locations along the route.
The Late Palaeo-Indians moved into the Thunder Bay area after the glaciers retreated, and stayed because of the deposits of jasper taconite, a hard chert rock that they used to make a wide variety of tools. Quarries, tool production and campsites have been found near former shoreline features of glacial Lake Minong and post-Lake Minong. Archaeologists believe that small groups of people moved north into the area each year to exploit caribou herds and manufacture stone tools. Archaeological sites have, however, so far revealed little about the shelters or structures of these people. The discovery of Blackduck pottery near Thunder Bay indicates the presence of aboriginal Blackduck residents from Late Woodland times, dating back to 1000 A.D. The Pukaskwa Pits, the puzzling rock structures found along the cobbled beaches of Lake Superior, also indicate the presence of long-ago cultures.
From Furs to Mines
The waters of Lake Superior have, for hundreds of years, served as a transportation route for the Algonquian nations and for the legendary coureurs de bois, such as Pierre-Esprit Radisson and Médard Chouart Des Groseilliers. In 1660, Radisson and Des Groseilliers, accompanied by their Odawa (Ottawa) companions, paddled Lake Superior and journeyed into Lake Nipigon, returning to New France the following year with fur-laden canoes. They carried news of a great saltwater sea just to the north of Lake Nipigon. Soon the canoes of hundreds of voyageurs plied the waters as the fur trade shifted both westward and northward over the next 200 years. In the 1880s, the Canadian Pacific Railway (CPR) began construction along the north shore of Superior, and many towns were created or enlarged, along with an expanding commercial fishery. Mining ventures also started up in the mid-1800s and rapidly multiplied, followed by forest operations, which expanded along the Superior shore.
But by the mid-1900s, many of the railway depots and towns had disappeared and the commercial fishery had virtually collapsed, only recently beginning a gradual comeback. Mining activity has waxed and waned throughout the century, whereas the forest industry, with its diversification of products, remains widespread.
Life Along the Shores
 The rocks and the forests of Superior’s coasts are festooned with lichens, vital indicators that the air here is clean. Other indicator plants point to unique microclimates and include various disjunct arctic-alpine plant species growing along the shoreline, on the diabase cliffs and in the canyons. Woodland caribou, once abundant, has been reduced to a scattered relict population. Nonetheless, in recent years the caribou have been successfully re-introduced to some of the islands in the lake. And the increasing numbers of reintroduced peregrine falcons nesting on the cliffs around Thunder Bay is a remarkable success story (Ecopoint 5).
Lake Superior is home to about 70 species of fish, predominantly native cold-water species such as lake trout, lake whitefish and lake cisco. It is also one of the last strongholds of the shortjaw cisco, a threatened species that once thrived in several of the Great Lakes. Species that have been introduced to the lake include pink, chinook and coho salmon, as well as rainbow trout and rainbow smelt. But many more unwanted alien species have also invaded the lake and they keep coming. The most infamous is the sea lamprey, a parasitic pest that attaches to larger fish with its suction mouth and teeth. It contributed significantly to the collapse of the  commercial fishery in the lake. Among other exotic aquatic species recently recorded in Lake Superior are an amphipod, or freshwater “side swimmer” shrimp, and three new fingernail clams. And there is a tiny mudsnail from New Zealand that can clone itself. How these species will affect the lake’s ecosystem is still unknown.
The lake is often calm on summer days but autumn is another matter. November storms provoked the Reverend George Grant (secretary to Sir Sandford Fleming’s expedition across Canada in 1872) to write: “Superior is a sea. It breeds storms, rains and fogs like the sea . . . it is wild, masterful and dread as the Black Sea.” The same could be said of it today. |
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