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This edited article about the Great Lakes originally appeared in Look and Learn issue number 752 published on 12 June 1976.
Imagine a lake nearly twice as wide as the Strait of Dover, and over 200 miles (about 320 km) long. These are the dimensions of the smallest of the Great Lakes of eastern North America, Lake Ontario.
Lake Superior, largest and farthest inland, is the world’s biggest fresh-water lake, and the five lakes together have an area of 95,000 square miles (245,000 sq km). With the St. Lawrence River, they make up a water system of enormous importance to many millions of people.
Lake Michigan is entirely within US territory, but the shores and waters of the rest – Lakes Superior, Huron, Erie and Ontario – are shared with Canada. A seventh of the USA’s population, and as many as a quarter of all Canadians, live and work around the lakes.
During the last of the great Ice Ages, much of North America was frozen over. Then, as the ice-cap and glaciers began to recede, some 15 to 20 thousand years ago, the troughs which the ice had hollowed out of the softer rocks of the region filled with water.
At first these lakes drained southward through what is now the Mississippi River system. As the ice retreated farther northwards, the lakes extended northwards, too. Their outflow switched to the east, reaching the Atlantic via the present Hudson valley. Finally the direction changed again, to the north-east, into the St. Lawrence River.
The Huron and Iroquois Indians who inhabited the lands round the lakes used them as their highway through the thickly forested region. The early French explorers were quick to realise their value as a route into the interior of the continent. Some even thought that the lakes offered an alternative to the eagerly-sought North-west Passage to the Orient. When the French pioneer Jean Nicolet landed on the western shore of Lake Michigan in 1634, he is said to have worn mandarin costume – being quite certain that he had reached China.
In the 17th and 18th centuries, the main importance of the lakes was as a route for fur-traders. On the river joining Lakes Ontario and Erie are the fearsome Niagara Falls, while between Erie and Huron, and the latter and Lake Superior, the traders found swift rivers with dangerous rapids. Canoes had at these points to be carried overland – the process known as “portage”.
When sailing ships were introduced in the 18th century, they were confined to the lake on which they were launched, except between Lakes Michigan and Huron, which are joined by a five-mile-wide strait, spanned today by the soaring Mackinac Bridge. Of the five lakes, only these two lie at the same level.
In many places the shores of the Great Lakes are now lined with expanding cities and great industrial developments. Toronto rears its skyscrapers on Lake Ontario’s north-west shore, Cleveland and Buffalo lie on Lake Erie. For 70 miles along the western margin of Lake Michigan, an almost continuous urban strip runs from Chicago, north to Milwaukee.
Much of the ancient forest has been felled. Where mines and factories have not replaced it, intensive farming is practised. Yet elsewhere the rugged beauty of the region survives. Rocky cliffs, wind-blown dunes and wooded inlets and creek mouths recall the pioneer days. In the winter, ice clogs the harbours and navigation becomes impossible.
Lake Superior is not only the largest of the lakes, but it also has a very distinctive character. The water is colder and clearer than in the other lakes, and its shore-line is more varied and picturesque. No fewer than 200 rivers feed the lake.
Running along the southern shore for a distance of some 14 miles (22 km), and facing the widest part of the lake, are the famous Pictured Rocks. These are steep cliffs of red sandstone, and get their name from the effect of “carving” produced by the erosive action of the waves.
Despite the tremendous development and population growth around the lakes, efforts have been made to preserve wildlife and natural scenery when possible. Along the Canadian shore of Lake Superior, moose and black bear are seen, and the lynx and timber wolf still prowl. The 45-mile (72-km)-long Isle Royale in this lake is protected as a National Park by the US government.
The lakes are naturally rich in fish, but in many areas they are threatened by pollution. Sewage and industrial waste encourages excessive growth of algae. As these water-plants first flourish and then decay, they consume great quantities of vital oxygen. Worst affected is Erie, much of which is regarded as a “dead lake”.
It is hoped that recent laws, and the pressure of public opinion, will bring about a remedy to this sad threat to nature.
Another danger to the fish could hardly be blamed on Man. This comes from the eel-like lamprey, which found its way into the lakes from the ocean. Fastening its sucker mouth on to trout, salmon and other valuable fish, it feeds on their vital juices, and leaves them to die. Happily a chemical has now been found which kills the lampreys without harming the other species.
As early as the first part of last century, communications between the lakes were being improved by the construction of canals and locks, and the clearing of natural passages. But it was not until 1959 that the final great step was achieved with the opening of the St. Lawrence Seaway.
This term properly belongs to the upper St. Lawrence River, and associated canals, which permit ocean-going ships to pass beyond Montreal and into Lake Ontario. But the name is popularly applied to the whole Great Lakes route, including the improved and deepened Welland Canal by-passing the Niagara falls, and the Soo canal and lock system at Sault Ste. Marie below Lake Superior.
Mighty freighters now steam into the heart of the continent, delivering cargoes and picking up wheat and other products from such ports as the USA’s Duluth and the Canadian Port Arthur – 2,300 miles (3,700 km) from the Atlantic, at the western end of Lake Superior.
It would be a mistake to think of the Great Lakes as placid stretches of water. Great storms can whip up waves of oceanic scale, and many a sunken wreck lies beneath the waters. Nor are the shores of the lakes immune to damage. Erosion of these, and even undermining of buildings, has set serious problems.
Yet these great inland seas are far more of a boon than a menace, and have made a major contribution to the life of two great nations.