Lake Superior


Lake Superior is the largest of the Great Lakes of North America, the world's largest freshwater lake by surface area, and the third largest freshwater lake by volume. It is shared by the Canadian province of Ontario to the north, the U.S. state of Minnesota to the west, and Wisconsin and the Upper Peninsula of Michigan to the south. The farthest north and west of the Great Lakes chain, Superior has the highest elevation of all five great lakes and drains into the St. Mary's River.

Name

The Ojibwe name for the lake is gichi-gami, meaning "great sea." Henry Wadsworth Longfellow wrote the name as "Gitche Gumee" in The Song of Hiawatha, as did Gordon Lightfoot in his song "The Wreck of the Edmund Fitzgerald." According to other sources, the actual Ojibwe name is Ojibwe Gichigami or Anishinaabe Gichigami. The 1878 dictionary by Father Frederic Baraga, the first one written for the Ojibway language, gives the Ojibwe name as Otchipwe-kitchi-gami.
The first French explorers approaching the great inland sea by way of the Ottawa River and Lake Huron during the 17th century referred to their discovery as le lac supérieur. Properly translated, the expression means "Upper Lake"—that is, the lake above Lake Huron. The lake was also called Lac Tracy by 17th century Jesuit missionaries. The British, upon taking control of the region from the French in the 1760s following the French and Indian War, anglicized the lake's name to Superior, "on account of its being superior in magnitude to any of the lakes on that vast continent".

Hydrography

Lake Superior empties into Lake Huron via the St. Marys River and the Soo Locks. Lake Superior is the largest freshwater lake in the world in area and the third largest in volume, behind Lake Baikal in Siberia and Lake Tanganyika in East Africa. The Caspian Sea, while larger than Lake Superior in both surface area and volume, is brackish; though presently isolated, prehistorically the Caspian has been repeatedly connected to and then isolated from the Mediterranean via the Black Sea.
Lake Superior has a surface area of, which is approximately the size of South Carolina or Austria. It has a maximum length of and maximum breadth of. Its average depth is with a maximum depth of. Lake Superior contains 2,900 cubic miles of water. There is enough water in Lake Superior to cover the entire land mass of North and South America to a depth of. The shoreline of the lake stretches .
American limnologist J. Val Klump was the first person to reach the lowest depth of Lake Superior on July 30, 1985, as part of a scientific expedition, which at 122 fathoms 1 foot below sea level is the second-lowest spot in the continental interior of the United States and the third-lowest spot in the interior of the North American continent after Iliamna Lake in Alaska and Great Slave Lake in the Northwest Territories of Canada at.
While the temperature of the surface of Lake Superior varies seasonally, the temperature below is an almost constant 39 °F. This variation in temperature makes the lake seasonally stratigraphic. Twice per year, however, the water column reaches a uniform temperature of 39 °F from top to bottom, and the lake waters thoroughly mix. This feature makes the lake dimictic. Because of its volume, Lake Superior has a retention time of 191 years.
Annual storms on Lake Superior regularly feature wave heights of over. Waves well over have been recorded.

Tributaries and outlet

Lake Superior is fed by more than 200 rivers, including the Nipigon River, the St. Louis River, the Pigeon River, the Pic River, the White River, the Michipicoten River, the Bois Brule River and the Kaministiquia River. Lake Superior drains into Lake Huron via the St. Marys River. There are rapids at the river's upper end, where the river bed has a relatively steep gradient. The Soo Locks enable ships to bypass the rapids and to overcome the height difference between Lakes Superior and Huron.

Water levels

The lake's average surface elevation is above sea level. Until approximately 1887, the natural hydraulic conveyance through the St. Marys River rapids determined the outflow from Lake Superior. By 1921, development in support of transportation and hydroelectric power resulted in gates, locks, power canals and other control structures completely spanning St. Marys rapids. The regulating structure is known as the Compensating Works and is operated according to a regulation plan known as Plan 1977-A. Water levels, including diversions of water from the Hudson Bay watershed, are regulated by the International Lake Superior Board of Control, which was established in 1914 by the International Joint Commission.
Lake Superior's water level was at a new record low in September 2007, slightly less than the previous record low in 1926. Water levels recovered within a few days.
Historic high water
The lake's water level fluctuates from month to month, with the highest lake levels in October and November. The normal high-water mark is above datum. In the summer of 1985, Lake Superior reached its highest recorded level at above datum. The winter of 1986 set new high-water records through the winter and spring months, ranging from to above Chart Datum.
Historic low water
The lake's lowest levels occur in March and April. The normal low-water mark is below datum. In the winter of 1926 Lake Superior reached its lowest recorded level at below datum. Additionally, the entire first half of the year included record low months. The low water was a continuation of the dropping lake levels from the previous year, 1925, which set low-water records for October through December. During the nine-month period of October 1925 to June 1926, water levels ranged from to below Chart Datum. In the summer of 2007 monthly historic lows were set; August at, September at.

Climate change

According to a study by professors at the University of Minnesota Duluth, Lake Superior may have warmed faster than its surrounding area. Summer surface temperatures in the lake appeared to have increased by about between 1979 and 2007, compared with an approximately increase in the surrounding average air temperature. The increase in the lake's surface temperature may be related to the decreasing ice cover. Less winter ice cover allows more solar radiation to penetrate and warm the water. If trends continue, Lake Superior, which freezes over completely once every 20 years, could routinely be ice-free by 2040. This would be a significant departure from historical records as, according to Hubert Lamb, Samuel Champlain reported ice along the shores of Lake Superior in June 1608. Warmer temperatures could lead to more snow in the lake effect snow belts along the shores of the lake, especially in the Upper Peninsula of Michigan. Two recent consecutive winters brought unusually high ice coverage to the Great Lakes, and on March 6, 2014, overall ice coverage peaked at 92.5%, the second-highest in recorded history. Lake Superior's ice coverage further beat 2014's record in 2019, reaching 95% coverage.

Geography

The largest island in Lake Superior is Isle Royale in the state of Michigan. Isle Royale contains several lakes, some of which also contain islands. Other well-known islands include Madeline Island in the state of Wisconsin, Michipicoten Island in the province of Ontario, and Grand Island in the state of Michigan.
The larger cities on Lake Superior include the twin ports of Duluth, Minnesota and Superior, Wisconsin; Thunder Bay, Ontario; Marquette, Michigan; and the twin cities of Sault Ste. Marie, Michigan, and Sault Ste. Marie, Ontario. Duluth-Superior, at the western end of Lake Superior, is the most inland point on the St. Lawrence Seaway and the most inland port in the world.
Among the scenic places on the lake are Apostle Islands National Lakeshore, Brockway Mountain Drive on the Keweenaw Peninsula, Isle Royale National Park, Porcupine Mountains Wilderness State Park, Pukaskwa National Park, Lake Superior Provincial Park, Grand Island National Recreation Area, Sleeping Giant and Pictured Rocks National Lakeshore.

Great Lakes Circle Tour

The Great Lakes Circle Tour is a designated scenic road system connecting all of the Great Lakes and the St. Lawrence River.

Climate

Lake Superior's size reduces the severity of the seasons of its humid continental climate. The water surface's slow reaction to temperature changes, seasonally ranging between 32 and 55 °F around 1970, helps to moderate surrounding air temperatures in the summer and winter, and creates lake effect snow in colder months. The hills and mountains that border the lake hold moisture and fog, particularly in the fall.
The lake's surface temperature rose by 4.5 °F from 1979 to 2006.
of the U.S. area bordering Lake Superior: Minnesota, Wisconsin, and the Upper Peninsula of Michigan
s and basement rock, showing the formation of the Midcontinent Rift containing today's Lake Superior

Geology

The rocks of Lake Superior's northern shore date back to the early history of the earth. During the Precambrian magma forcing its way to the surface created the intrusive granites of the Canadian Shield. These ancient granites can be seen on the North Shore today. It was during the Penokean orogeny, part of the process that created the Great Lakes Tectonic Zone, that many valuable metals were deposited. The region surrounding the lake has proved to be rich in minerals. Copper, iron, silver, gold and nickel are or were the most frequently mined. Examples include the Hemlo gold mine near Marathon, copper from the Keweenaw Peninsula and the Mamainse Point Formation, iron from the Gogebic Range, silver at Silver Islet and uranium at Theano Point.
The mountains steadily eroded, depositing layers of sediments that compacted and became limestone, dolomite, taconite and the shale at Kakabeka Falls.
The continent was later riven, creating one of the deepest rifts in the world. The lake lies in this long-extinct Mesoproterozoic rift valley, the Midcontinent Rift. Magma was injected between layers of sedimentary rock, forming diabase sills. This hard diabase protects the layers of sedimentary rock below, forming the flat-topped mesas in the Thunder Bay area.
Amethyst formed in some of the cavities created by the Midcontinent Rift and there are several amethyst mines in the Thunder Bay area.
Lava erupted from the rift and formed the black basalt rock of Michipicoten Island, Black Bay Peninsula, and St. Ignace Island.
During the Wisconsin glaciation 10,000 years ago, ice covered the region at a thickness of. The land contours familiar today were carved by the advance and retreat of the ice sheet. The retreat left gravel, sand, clay and boulder deposits. Glacial meltwaters gathered in the Superior basin creating Lake Minong, a precursor to Lake Superior. Without the immense weight of the ice, the land rebounded, and a drainage outlet formed at Sault Ste. Marie, which would become known as St. Mary's River.

History

The first people came to the Lake Superior region 10,000 years ago after the retreat of the glaciers in the last Ice Age. They are known as the Plano, and they used stone-tipped spears to hunt caribou on the northwestern side of Lake Minong.
The next documented people are known as the Shield Archaic. Evidence of this culture can be found at the eastern and western ends of the Canadian shore. They used bows and arrows, dugout canoes, fished, hunted, mined copper for tools and weapons, and established trading networks. They are believed to be the direct ancestors of the Ojibwe and Cree.
The Laurel people developed seine net fishing, evidence being found at rivers around Superior such as the Pic and Michipicoten.
s at Lake Superior Provincial Park, Ontario
Another culture known as the Terminal Woodland Indians has been found. They were Algonkian people who hunted, fished and gathered berries. They used snow shoes, birch bark canoes and conical or domed lodges. At the mouth of the Michipicoten River, nine layers of encampments have been discovered. Most of the Pukaskwa Pits were likely made during this time.
The Anishinaabe, which includes the Ojibwe or Chippewa, have inhabited the Lake Superior region for over five hundred years and were preceded by the Dakota, Fox, Menominee, Nipigon, Noquet and Gros Ventres. They called Lake Superior either Ojibwe Gichigami or Anishnaabe Gichgamiing. After the arrival of Europeans, the Anishinaabe made themselves the middle-men between the French fur traders and other Native peoples. They soon became the dominant Native American nation in the region: they forced out the Sioux and Fox and won a victory against the Iroquois west of Sault Ste. Marie in 1662. By the mid-18th century, the Ojibwe occupied all of Lake Superior's shores.
, Minnesota
In the 18th century, the fur trade in the region was booming, with the Hudson's Bay Company having a virtual monopoly until 1783, when the North West Company was formed to rival the Hudson's Bay Company. The North West Company built forts on Lake Superior at Grand Portage, Fort William, Nipigon, the Pic River, the Michipicoten River, and Sault Ste. Marie. But by 1821, with competition taking too great a toll on both, the companies merged under the Hudson's Bay Company name.
Many towns around the lake are either current or former mining areas, or engaged in processing or shipping. Today, tourism is another significant industry; the sparsely populated Lake Superior country, with its rugged shorelines and wilderness, attracts tourists and adventurers.

Shipping

Lake Superior has been an important link in the Great Lakes Waterway, providing a route for the transportation of iron ore as well as grain and other mined and manufactured materials. Large cargo vessels called lake freighters, as well as smaller ocean-going freighters, transport these commodities across Lake Superior.
Shipping was slow to arrive at Lake Superior in the 19th century. The first steamboat to run on the lake was the Independence, which didn't appear until 1847, compared to the arrival of the first steamers on the other Great Lakes beginning in 1816.
Because of ice, the Lake is closed to shipping from mid-January to late March. Exact dates for the shipping season vary each year, depending on weather conditions that form and break the ice.

Shipwrecks

The southern shore of Lake Superior between Grand Marais, Michigan, and Whitefish Point is known as the "Graveyard of the Great Lakes" and more ships have been lost around the Whitefish Point area than any other part of Lake Superior. These shipwrecks are now protected by the Whitefish Point Underwater Preserve.
Storms that claimed multiple ships include the Mataafa Storm in 1905 and the Great Lakes Storm of 1913.
Wreckage of —a ore carrier that sank on October 11, 1907, during a Lake Superior storm in 77 fathoms of water—was located in August 2007. All but Charles G. Pitz of Cypruss 23 crew perished. The ore carrier sank in Lake Superior on her second voyage, while hauling iron ore from Superior, Wisconsin, to Buffalo, New York. Built in Lorain, Ohio, Cyprus was launched August 17, 1907.
In 1918 the last warships to sink in the Great Lakes, French minesweepers Inkerman and Cerisoles, vanished in a Lake Superior storm, perhaps upon striking the uncharted danger of the Superior Shoal in an otherwise deep part of the lake. With 78 crewmembers dead, their sinking marked the largest loss of life on Lake Superior to date.
was the latest major shipwreck on Lake Superior, sinking from Whitefish Point in a storm on November 10, 1975. The wreck was immortalized by Gordon Lightfoot in his ballad "The Wreck of the Edmund Fitzgerald". All 29 crew members perished when the ship sank, and no bodies were ever recovered. Edmund Fitzgerald was swallowed up so intensely by Lake Superior that the ship split in half; her two pieces are approximately apart in a depth of 91 fathoms 4 feet.
According to legend, "Lake Superior seldom gives up her dead". This is because of the unusually low temperature of the water, estimated at under on average around 1970. Normally, bacteria feeding on a sunken decaying body will generate gas inside the body, causing it to float to the surface after a few days. But Lake Superior's water is cold enough year-round to inhibit bacterial growth, and bodies tend to sink and never resurface. This is alluded to in Lightfoot's "The Wreck of the Edmund Fitzgerald" ballad with the line "The lake, it is said, never gives up her dead". Fitzgerald adventurer Joe MacInnis reported that, in July 1994, explorer Frederick Shannon's Expedition 94 to the wreck of Edmund Fitzgerald discovered and filmed a man's body near the port side of her pilothouse, not far from the open door, "fully clothed, wearing an orange life jacket, and lying face down in the sediment".
, Ontario
, Michigan

Ecology

More than 80 species of fish have been found in Lake Superior. Species native to the lake include: banded killifish, bloater, brook trout, burbot, cisco, lake sturgeon, lake trout, lake whitefish, longnose sucker, muskellunge, northern pike, pumpkinseed, rock bass, round whitefish, smallmouth bass, walleye, white sucker and yellow perch. In addition, many fish species have been either intentionally or accidentally introduced to Lake Superior: Atlantic salmon, brown trout, carp, chinook salmon, coho salmon, freshwater drum, pink salmon, rainbow smelt, rainbow trout, round goby, ruffe, sea lamprey and white perch.
Lake Superior has fewer dissolved nutrients relative to its water volume than the other Great Lakes and so is less productive in terms of fish populations and is an oligotrophic lake. This is a result of the underdeveloped soils found in its relatively small watershed. It is also a reflection of relatively small human population and small amount of agriculture in its watershed. However, nitrate concentrations in the lake have been continuously rising for more than a century. They are still much lower than levels considered dangerous to human health; but this steady, long-term rise is an unusual record of environmental nitrogen buildup. It may relate to anthropogenic alternations to the regional nitrogen cycle, but researchers are still unsure of the causes of this change to the lake's ecology.
As for other Great Lakes fish, populations have also been affected by the accidental or intentional introduction of foreign species such as the sea lamprey and Eurasian ruffe. Accidental introductions have occurred in part by the removal of natural barriers to navigation between the Great Lakes. Overfishing has also been a factor in the decline of fish populations.

General