Lake Superior, Landsat photographyName
In the Ojibwe language, the lake is called "Gichigami" ("big water"), but it is better known as "Gitche Gumee" as recorded by Henry Wadsworth Longfellow in The Song of Hiawatha. Lake Superior is referred to as "Gitche Gumee" in the song The Wreck of the Edmund Fitzgerald, by Gordon Lightfoot.
The lake was named le lac supérieur, or "Upper Lake," in the seventeenth century by French explorers because it was located above Lake Huron.(Nute, 1946)
Hydrography
Lake Superior is the largest freshwater lake in the world by surface area. Lake Baikal in Russia is larger by volume, as is Lake Tanganyika (The Caspian Sea, while vastly larger than Lake Superior in both surface area and volume, is saline; though presently isolated, in the past, it has been repeatedly connected to, and isolated from, the Mediterranean via the Black Sea).
Lake Superior (48°00’N, 88°00’W) has a surface area of 31,820 square miles (82,414 km²)[1]—which is larger than South Carolina. It has a maximum length of 350 miles (563 km) and maximum breadth of 160 miles (257 km). Its average depth is 483 feet (147 m) with a maximum depth of 1,333 feet (406 m).[1] Lake Superior contains 2,900 cu mi (12,100 km³) of water. There is enough water in Lake Superior to cover the entire land mass of North and South America with a foot (30 cm) of water. The shoreline of the lake stretches 2,726 miles (4,385 km) (including islands). The lake's elevation is 600 feet (183 m)[1] above sea level. 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.
Annual storms on Lake Superior regularly record wave heights of over 20 feet (6 m).[1] Waves well over 30 feet (9 m) have been recorded.[3]
Water levels, including diversions of water from the Hudson Bay watershed, are governed by the International Lake Superior Board of Control which was established in 1914 by the International Joint Commission.
Tributaries and outlet
The lake is fed by over 200 rivers. The largest include the Nipigon River, the St. Louis River, the Pigeon River, the Pic River, the White River, the Michipicoten River, the Brule River and the Kaministiquia River. Lake Superior drains into Lake Huron by the St. Marys River. The rapids on the river necessitate the Sault Locks (pronounced "soo"), a part of the Great Lakes Waterway, to move boats over the 25 foot (7.6 m) height difference from Lake Huron.
Geography
The largest island in Lake Superior is Isle Royale in the state of Michigan. Other large famous islands include Madeline Island in the state of Wisconsin and Michipicoten in the province of Ontario.
The larger towns on Lake Superior include: the twin ports of Duluth, Minnesota and Superior, Wisconsin; Thunder Bay, Ontario; Marquette, Michigan; and the two cities of Sault Ste. Marie, in Michigan and in Ontario. Duluth, at the western tip of Lake Superior, is the most inland point on the Saint Lawrence Seaway and the most inland port in the world.
Among the scenic places on the lake are: the Apostle Islands National Lakeshore; Isle Royale National Park; Pukaskwa National Park; Lake Superior Provincial Park; Grand Island National Recreation Area; Sleeping Giant (Ontario);and Pictured Rocks National Lakeshore.
Climate
Lake Superior's size creates a localized oceanic or maritime climate (more typically seen in locations like Nova Scotia) [4]. The water's slow reaction to temperature changes 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 form a bowl, which holds moisture and fog, particularly in the fall. The Lake Superior's surface temperature has warmed by 2.5 °C since 1979, which has been attributed to global warming.
Geology
Lake Superior's North Shore dates back to the beginnings of the earth. About 2.7 billion years ago, 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 in this period, the Penokean orogeny, 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 at Point Mamainse, silver at Silver Islet, and uranium at Theano Point.
The mountains steadily eroded starting about 2.49 billion years ago, depositing layers of sediments which compacted and became limestone, dolostone, taconite, and the shale at Kakabeka Falls.
About 1.1 billion years ago, the continent was rifted, creating one of the deepest rifts in the world. The lake lies above this long-extinct Mesoproterozoic rift valley, the Midcontinent Rift, which explains its great depths. 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.
Lava erupted from the rift and formed the black basalt rock of Michipicoten Island, Black Bay Peninsula, and St. Ignace Island.
Around 1.6 million years ago, during the last Great Ice Age, ice covered the region at a thickness of 1.25 miles (2 km). The land contours familiar today were carved by the advance and retreat of the ice sheet. The retreat some 10,000 years ago, left gravel, sand, clay, and boulder deposits. Glacial meltwaters gathered in the Superior basin creating Lake Minong, a precursor to Lake Superior.[6] 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 were known as the Plano, and they used stone-tipped spears to hunt caribou on the northwestern side of Lake Minong.
The next documented people were known as the Shield Archaic (c. 5000-500 B.C.). 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.[7]
The Laurel people (c. 500 B.C. to A.D. 500) developed seine net fishing, evidence being found at rivers around Superior such as the Pic and Michipicoten.
Another culture known as the Terminal Woodland Indians (c. A.D. 900-1650) 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 Anishinabe, also known as 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 Anishnaabe Chi Gaming, or "the Ojibwe's Ocean". After the arrival of Europeans, the Anishinabe made themselves the middle-men between the French fur traders and other Native peoples. They soon became the dominant Indian 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-1700s, the Ojibwe occupied all of Lake Superior's shores.
In the 1700s, the fur trade in the region was booming, with the Hudson's Bay Company (HBC) having a virtual monopoly. In 1783, however, the North West Company (NWC) was formed to rival HBC. The NWC built forts on Lake Superior at Grand Portage, 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 as 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 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.
Shipwrecks
The last major shipwreck on Lake Superior was that of SS Edmund Fitzgerald in 1975.
According to an old sailor's tale, Lake Superior never gives up her dead. This is due to the temperature of the water. Normally bacteria feeding off a sunken decaying body will generate gas inside the body, causing it to float to the surface after a few days. The water in Lake Superior, however, is cold enough year-round to inhibit bacterial growth, meaning bodies tend to sink and never surface.[10] This is poetically alluded to in Gordon Lightfoot's famous ballad, The Wreck of the Edmund Fitzgerald.
Ecology
Although part of a single system, each of the Great Lakes is different. In volume, Lake Superior is the largest. It is also the deepest and coldest of the five. Superior could contain all the other Great Lakes and three more Lake Eries. Because of its size, Superior has a retention time of 191 years.
According to a study by professors at the University of Minnesota Duluth, Lake Superior has been warming faster than its surrounding climate. Summer surface temperatures in the lake have increased about 4.5 degrees Fahrenheit since 1979, compared with about a 2.7-degree increase in the surrounding average air temperature. The increase in the lake’s surface temperature is not only due to climate change but also due to the decreasing ice cover. Less winter ice cover allows more solar radiation to penetrate the lake and warm the water. If trends continue Lake Superior, which freezes over completely once every 20 years, could routinely be ice-free by 2040. These warmer temperatures can actually lead to more snow in the lake effect snow belts along the shores of the lake, especially in the Upper Peninsula of MIchigan.
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