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Podcast Transcript

Located between Canada and the United States is one of the largest bodies of freshwater in the world, Lake Superior. 

Lake Superior is the largest and deepest of the Great Lakes, and it is the first of the lakes in terms of water flow. 

Despite being the largest of the Great Lakes, it has the fewest number of people living on its shores, yet it is one of the most important economically. 

Learn more about Lake Superior, the big lake they call Gitche Gumee, on this episode of Everything Everywhere Daily. 

The story of Lake Superior begins well before humans gazed upon it—in fact before humans existed. 

Lake Superior is situated in the region known as the Canadian Shield, a massive area of ancient bedrock that dates back to the Precambrian era about 1.1 billion years ago. The Canadian shield is the location of some of the oldest exposed rocks on Earth.

One of the most significant geological events during this time was the formation of the Midcontinent Rift System, a massive crack in the Earth’s crust that stretched from what is now Lake Superior all the way to Kansas. 

This rift was caused by tectonic forces pulling the continent apart, which created deep valleys and filled them with molten rock. This magma cooled and solidified into basalt, forming the foundation of what would later become Lake Superior’s basin.

After the rifting ceased, the area underwent a period of millions of years of uplift and erosion. Over these millions of years, edimentary rocks, such as sandstone, were deposited over the ancient volcanic rock, creating a diverse geologic landscape.

Fast-forward to the Quaternary Period, which started about 2.5 million years ago. This began an era of periodic ice ages.

The current shape of Lake Superior was primarily sculpted during the last Ice Age. As glaciers advanced and retreated across North America, they scoured the land, carving out deep basins in the bedrock. 

About 10,000 years ago, as the glaciers began to retreat at the end of the last glacial period, massive meltwater lakes formed. The largest of these glacial lakes was Glacial Lake Duluth, a precursor to modern Lake Superior.

Lake Duluth was smaller and was located in what is today the western lobe of Lake Superior.

As the ice sheets melted, water levels fluctuated, and the landscape rebounded from the removal of the weight of the glaciers, a process known as isostatic rebound, slowly giving rise to the lake’s modern shape.

Isostatic rebound is still ongoing in regions covered in ice during the last ice age. The southern shore of Lake Superior on the American side is rising ever so faster than the northern shore on the Canadian side. 

Over the last several thousand years, Lake Superior’s water levels stabilized, leading to its present form.

Now resting in the ancient rift valley created by the Midcontinent Rift System, the lake holds about 10% of the world’s fresh surface water. 

Lake Superior has a surface area of 82,100 square kilometers or 31,700 square miles. This would make it the largest fresh water lake in the world by area.

Note: The Caspian Sea is larger, but it isn’t quite a freshwater lake because it has brackish water with 1.2% salinity, not fresh water. On some lists, it will be listed, and on other lists, it will not.

At its deepest point, the lake is 1,333 feet or 406 meters deep due to the erosion of the glaciers and the depth of the ancient Midcontinent Rift. It is only the 42nd deepest lake in the world. Lake Baikal and lakes along the East African Rift, such as Lake Tanganyika, are all much deeper. 

In terms of volume, it ranks behind Baikal and Tanganyika for fresh water lakes. However, it holds more water than the other four Great Lakes put together. 

Another measure of a lake is its Retention time. Retention time is the amount of time water spends in a lake. It is determined by dividing the lake’s volume by its water outflow. The other Great Lakes have retention times ranging from 2.6 years for Lake Erie to 99 years for Lake Michigan.

Lake Superior’s retention time is 191 years old due to its volume and the fact that it only has one outflow, the Saint Mary River. More on that in a bit. 

Human history around Lake Superior dates back to at least 10,000 years, soon after the glaciers retreated. 

Indigenous peoples, particularly the Ojibwe, have lived in the Lake Superior region for thousands of years, relying on its abundant resources for food, transportation, and spiritual significance.

The lake’s waters and surrounding forests provided sustenance, while its shores became important for trade networks as indigenous peoples moved goods like copper, furs, and tools.

Just as an aside, in Gordon Lightfoot’s song “The Wreck of the Edmund Fitzgerald,” he uses the line that I had in the introduction: “the big lake they call Gitche Gumee.” 

This actually is a mispronunciation of the Ojibwe word “gichi-gami” which translates to “great sea.” If you live in a landlocked part of the world and come upon Lake Superior, then it would certainly seem like a great sea.

Gitche Gumee actually comes from Henry Wadsworth Longfellow, who used it in the poem The Song of Hiawatha.

The first Europeans to explore Lake Superior were French explorers and fur traders. In the early 1600s, Étienne Brûlé is credited as being the first European to see Lake Superior.

By the mid-1600s, other French explorers visited the region and recognized the lake’s importance for fur trading.

Lake Superior played a key role in the fur trade during the 17th and 18th centuries. French traders established trading posts along its shores, and the lake became a major part of the transportation route known as the Voyageur’s Highway, which connected Montreal to the interior of North America.

Following the British acquisition of New France in North America in 1763 and the establishment of the United States, American settlers began to move into the Lake Superior region. 

After the War of 1812, a new border was established through the lake in 1817. The United States established Fort Brady in Sault Ste. Marie, Michigan, which was located on the rapids in St. Mary River, the choke point for access into or out of Lake Superior by water. 

The discovery of large deposits of copper and iron ore around Lake Superior in the mid-1800s led to a mining boom.

The Keweenaw Peninsula, located on the southern shore of Lake Superior, became one of the most productive copper mining regions in the world. Iron mining also became crucial in the Mesabi Range, near Lake Superior’s western shore in Minnesota, and in the Marquette Range in Michigan’s Upper Peninsul. 

These mining activities transformed the region economically and socially, drawing thousands of immigrants, especially from Europe, to work in the mines and surrounding industries.

It also necessitated the creation of a system of locks so ships could bypass the rapids on the St. Mary River that connects Lake Superior with Lake Huron. 

The first lock was built on the Canadian side of the river as early as 1798. However, it was a very simple lock designed for the fur trade. The United States destroyed it in 1814 as part of the 1812 war. 

With growing copper and iron production, the United States next built a lock in 1853. 

As of the time of this recording, there are currently three locks that allow access across the rapids in the St. Mary River in Sault Ste. Marie, Michigan, and Sault Ste. Marie, Ontario. Each lock will take ships up or down 21 feet or 6.4 meters to avoid the St. Mary’s rapids.

There is one smaller Canadian lock which is used for smaller craft and pleasure vessels. The American side has two locks, the Poe Lock, built in 1896, and the MacArthur Lock, built in 1943, which are used for larger ore haulers. 

There is a third lock on the American side which is currently under construction. It is expected to be complete in 2030 and it will replace two older locks that were decommissioned in 2010.

The Soo Locks allow all of Lake Superior to be accessible to the Great Lakes Seaway Navigation System.  From there, you can go through Lake Huron to Lake Ontario, Lake Erie, and then the Saint Lawrence Seaway. This effectively makes the Port of Duluth, Minnesota, the westernmost Atlantic Ocean port. 

There are approximately 10,000 ships that pass through the Soo locks every year. 

Because of how far north it is, there aren’t any major cities on Lake Superior like you see on the other Great Lakes. The largest city on Lake Superior is Thunder Bay, Ontario, which has a population of a little over 100,000. 

As a tourist attraction, Lake Superior differs from other great lakes. 

For starters, the lake is cold. Very cold. The average temperature of the lake water year around is about 40 degrees Fahrenheit or 4 degrees celsius.  The lake has never frozen over in recorded human history, but there have been times when ice cover has reached 95%. Because of the enormous volume of water it retains a lot of heat, even thought it has a low temperature. 

I suppose you could technically go swimming in Lake Superior, but most people wouldn’t. 

Lake Superior is also the cleanest of the Great Lakes. This has resulted in exceptional clarity. In parts of the lake, there is underwater visibility up to 27 feet or 8.2 meters.

Several notable protected areas are in and around the lake. On the Canadian side is Pukaskwa National Park. It is one of the most remote parks in Ontario, far away from the populated parts of the province. 

In Wisconsin is the Apostle Islands National Lakeshore. It is a group of 21 islands and a stretch of shoreline along Lake Superior in northern Wisconsin, known for its stunning sea caves, old-growth forests, and historic lighthouses.

In the Upper Peninsula of Michigan is Pictured Rocks National Lakeshore. It is renowned for its striking multicolored sandstone cliffs, waterfalls, and pristine beaches.

Perhaps the crown jewel of Lake Superior is Isle Royal National Park, the largest island in the lake. Technically, it is part of Michigan even thought it is much closer to both Minnesota and Ontario.  

The reason why it is part of Michigan instead of Minnesota has to do with the deal, which made the city of Toledo part of Ohio. 

Isle Royale is the least visited national park outside of Alaska, and, oddly enough, it is the most revisited park in the National Park Service. The reason why it gets so few visitors is because it is an island that requires a ferry ride to get there, and it is the only park outside of Alaska that is closed in the winter. 

Isle Royale is almost entirely wilderness. One of the things it is well known for is its population of moose and wolves. At some point over a century ago, some moose and wolves made it to the island during a particularly harsh winter when the lake froze between it and the mainland. 

The moose and wolves have lived in a textbook-like case of predators and prey on the island. When the moose population rose, it was soon followed by a rise in the wolf population, which would decrease the moose population, which would subsequently reduce the wolf population. 

Because everything took place on an island that had no other megafauna, researchers would track the population of moose and wolves every year. 

Many people make the popular trip of circumnavigating the entire lake. The Lake Superior Circle Tour is a route that will take you 1,300 miles or 2,000 kilometers and require two border crossings. 

Lake Superior remains culturally and economically important to both the United States and Canada. Its status as one of the largest and most important fresh water lakes in the world is all due to geologic forces that created it millions of years ago.