Those of us lucky enough to live in Ontario often take the Great Lakes for granted. We might not realize that one-fifth of all the fresh surface water in the world — that works out to 27 quadrillion litres — is contained within them. If all that water were spread across the surface of the United States’ “lower 48,” it would submerge the country to a depth of three metres.
We might not think, either, of what it was like before they existed, but the Great Lakes are actually a fairly recent addition to the landscape. In fact, they didn’t begin to appear until near the end of the last Ice Age about 15,000 years ago — nothing more than a camera flash in the entire picture of our Earth’s history.
If we could take a time machine and travel back 18,000 years, we would see that what is today Ontario was covered in a thick sheet of ice, a sheet that in some places measured four kilometres deep. That was at the height of the last Ice Age. After that time, this huge glacier began to melt and, as it retreated northward, it left behind immense depressions that it had dug into the Earth’s surface. The melting ice began to fill up those depressions, creating the predecessors to our modern-day Great Lakes.
The release of all of that weight of ice also began to allow the land to “bounce” back and, over time, the landscape started to tilt at different angles. A spillway that emptied through Lake Nipissing and down the Ottawa River stopped flowing and a new one — the one we call the St. Lawrence River — opened up.
The changes that formed the Great Lakes are not yet finished. It’s been just the past 10,000 years that Lake Huron has been emptying into Lake Erie. At that time, all of the upper lakes began to empty into the Niagara River, creating the volume of water that flows over Niagara Falls today.
As the eastern end of Erie continues to rise, eventually the lake will reverse its flow and begin to empty back up the Detroit and St. Clair rivers and into Lake Huron. The waters of the upper lakes will then begin to empty into the Mississippi River system at Chicago.
But that’s not likely to happen any time soon. It takes a great many years for the Earth’s surface to adjust itself enough to precipitate such immense changes, so don’t worry about Niagara running dry for a few millennia yet.
Ever wonder where the Great Lakes got their names? Wonder no more!
Lake Ontario stretches 310 kilometres by 85 kilometres and has an average depth of 86 metres.
The first European to name it was Champlain, who dubbed it Lac de St. Louis in 1632. Nearly three decades later, it was named Lacus Ontarius by the Jesuit historian, Creuxius, after the Iroquois work meaning “beautiful lake.” With a slight adjustment, the name stuck.
Lake Erie measures 388 kilometres by 92 kilometres and is the shallowest of the Great Lakes, with an average depth of 19 metres.
Erie is an abbreviated form of Erielhonan, which means “long tail” in the Iroquois language. The First Nations people who lived along its southern shore when Europeans arrived called themselves the “people of the long tail cat,” after the mountain lions that lived there at the time. The name was shortened and attached to the lake.
Lake Huron measures 331 kilometres by 294 kilometres and has an average depth of 59 metres.
Initially, the French explorers called Huron La Mer Douce, or the “sweet” or “fresh-water sea”. A map in 1656 labelled it Karegnondi, but later charts used Lac des Hurons, for the Huron First Nation people who lived along its eastern shores.
Lake Michigan, the only Great Lake totally within the United States, measures 190 kilometres by 494 kilometres. It has an average depth of 85 metres.
To Champlain, Michigan was Le Grand Lac. Later, it went through Lake of the Stinking Water and Lake of the Puants, named for the First Nation people who lived along its waters. For a time, it was called Lac St. Joseph and, later, Lac des Illinois, because beyond it lay the country of the Illinois people. It also was sometimes named Lac Dauphin. Finally, the Indian name for the water, “Michi gami,” was anglicized to Michigan.
Lake Superior is the largest of the five, stretching 563 kilometres by 257 kilometres and averaging 152 metres deep.
Early on, the French referred to this lake as Lac Supérieur, meaning “the upper lake.” The First Nations people called it “Kitchi-gummi,” which in Chippewa means “great water” or “great lake.” While for a time the Jesuit name Lac Tracy stuck, Superior it has nearly always been in English and French.
Did you know ...
• That if you lived in the United States there would be six Great Lakes? No, they’re not adding tiny Lake St. Clair, which people often mistakenly assume is a Great Lake. But former U.S. president Bill Clinton actually signed a bill in 1998 that officially recognized Lake Champlain as the sixth Great Lakes. Go figure.
• That only the polar ice caps and Lake Baikal in Siberia contain more fresh water than the Great Lakes?
• That the total surface area of all the Great Lakes is 244,000 square kilometres? That’s about the same size as the entire nation of Britain, which includes England, Wales, Scotland and Northern Ireland. In fact, if you took the entire shoreline of all of the lakes, the length would be 44 per cent of the circumference of the Earth.
• That 45 million people live in the Great Lakes basin? One-third live in Canada and two-thirds in the U.S.
• That 186 species of fish and other water creatures now living in the Great Lakes are not native to those waters? Most of them have arrived in the past quarter-century. Sources: Great Lakes Information Network; Environment Canada; CIA World Factbook; The Great Lakes: The natural history of a changing region, by Wayne Grady.