The Laurentian Great Lakes are a chain of freshwater lakes located in eastern North America, on the Canada–United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth. They are sometimes referred to as inland seas or Canada and the United States' Third Coast.
|Lake Erie||Lake Huron||Lake Michigan||Lake Ontario||Lake Superior|
|Major settlements|| Buffalo, NY|
| Sarnia, ON|
Owen Sound, ON
Port Huron, MI
Bay City, MI
| Chicago, IL|
Green Bay, WI
Traverse City, MI
Grand Haven, MI
| Hamilton, ON|
| Duluth, MN|
Sault Ste. Marie, ON
Thunder Bay, ON
Period = from:-1000 till:600 TimeAxis = orientation:vertical ScaleMajor = unit:year increment:500 start:-1000 ScaleMinor = unit:year increment:100 start:-1000
Define $elevation = shift:(0,15) mark:(line,textoutsidebar) textcolor:textoutsidebar Define $avgdepth = mark:(line,textinbar) textcolor:textinbar Define $maxdepth = shift:(0,-11) mark:(line,textoutsidebar) textcolor:textoutsidebar
bar:Superior from:-732 till:600 width:194 color:blue1
$elevation at:600 text:"600 ft (183 m)"
$avgdepth at:117 shift:(0,1) text:"483 ft (147 m)"
$maxdepth at:-732 text:"1,332 ft (406 m)"
bar:Michigan from:-348 till:577 width:113 color:blue5
$elevation at:577 text:"577 ft (176 m)"
$avgdepth at:298 shift:(0,2) text:"279 ft (85 m)"
$maxdepth at:-348 text:"925 ft (282 m)"
bar:Huron from:-173 till:577 width:101 color:blue3
$elevation at:577 text:"577 ft (176 m)"
$avgdepth at:382 shift:(0,1) text:"195 ft (59 m)"
$maxdepth at:-173 text:"750 ft (229 m)"
bar:Erie from:359 till:569 width:49 color:blue2
$elevation at:569 text:"569 ft (173 m)"
$avgdepth at:507 align:left shift:(30,2) textcolor:textoutsidebar text:"62 ft (19 m)"
$maxdepth at:359 text:"210 ft (64 m)"
bar:Ontario from:-559 till:243 width:44 color:blue4
$elevation at:243 text:"243 ft (74 m)"
$avgdepth at:-40 shift:(0,2) text:"283 ft (86 m)"
$maxdepth at:-559 text:"802 ft (244 m)"
align:left shift:(35,0) textcolor:green
|Notes:||The area of each rectangle is proportionate to the volume of each lake. All measurements at Low Water Datum.|
The Great Lakes are also connected to the Gulf of Mexico by way of the Illinois River (from Chicago), to the Mississippi, to the Gulf. An alternate track is via the Illinois River (from Chicago), to the Mississippi, to the Ohio, up the Ohio, and then through the Tennessee-Tombigbee Waterway (combination of a series of rivers and lakes and canals), to Mobile Bay and the Gulf. Commercial tug-and-barge traffic on these waterways is heavy.
Pleasure boats can also enter or exit the Great Lakes by way of the Erie Canal and Hudson River in New York. The Erie Canal connects to the Great Lakes at the east end of Lake Erie (at Buffalo, NY) and at the south side of Lake Ontario (at Oswego, NY).
The combined surface area of the lakes is approximately —nearly the same size as the United Kingdom, and larger than the U.S. states of New York, New Jersey, Connecticut, Rhode Island, Massachusetts, Vermont and New Hampshire combined.
The foundational geology which created the conditions shaping the present day upper Great Lakes was laid from 1.1 to 1.2 billion years ago, when two previously fused tectonic plates split apart and created the Midcontinent Rift. A valley was formed providing a basin that eventually became modern day Lake Superior. When a second fault line, the Saint Lawrence rift, formed approximately 570 million years ago, the basis for Lakes Ontario and Erie were created, along with what would become the St. Lawrence River.
The Great Lakes were formed at the end of the last ice age about 10,000 years ago, when the Laurentide ice sheet receded. When this happened, the glaciers left behind a large amount of meltwater (see Lake Agassiz) which filled up the basins that the glaciers had carved, thus creating the Great Lakes as we know them today. Because of the uneven nature of glacier erosion, some higher hills became Great Lakes islands. The Niagara Escarpment follows the contour of the Great Lakes between New York and Wisconsin.
The Great Lakes have been observed to help strengthen storms, such as Hurricane Hazel in 1954, and a frontal system in 2007 that spawned a few tornadoes in Michigan and Ontario, picking up warmth from the lakes to fuel them. Also observed in 1996, was a rare subtropical cyclone forming in Lake Huron, dubbed the 1996 Lake Huron cyclone.
The main business of many of the passenger lines in the 1800s was transporting immigrants. Many of the larger cities owe their existence to their position on the lakes as a freight destination as well as for being a magnet for immigrants. After railroads and surface roads developed, the freight and passenger businesses dwindled and except for ferries and a few foreign cruise ships, now has vanished.
The immigration routes still have an effect today. Immigrants often formed their own communities and some areas have a pronounced ethnicity, such as Dutch, German, Polish, Finnish, and many others. Since many immigrants settled for a time in New England before moving westward, many areas on the U.S. side of the Great Lakes also have a New England feel, especially in home styles and accent.
Since general freight these days is transported by railroads and trucks, domestic ships mostly move bulk cargoes, such as iron ore, coal and limestone for the steel industry. The domestic bulk freight developed because of the nearby mines. It was more economical to transport the ingredients for steel to centralized plants rather than try to make steel on the spot. Ingredients for steel, however, are not the only bulk shipments made. Grain exports are also a major cargo on the lakes.
In the 19th and early 20th centuries, iron and other ores such as copper were shipped south on (downbound ships), and supplies, food, and coal were shipped north (upbound). Because of the location of the coal fields in Pennsylvania and West Virginia, and the general northeast track of the Appalachian Mountains, railroads naturally developed shipping routes that went due north to ports such as Erie, Pennsylvania and Ashtabula, Ohio.
Because the lake maritime community largely developed independently, it has its own language. Ships, no matter the size, are called boats. When the sailing ships gave way to steamships, they were called steamboats—the same term used on the Mississippi. The ships also have a distinctive design. Ships that primarily trade on the lakes are known as lakers. Foreign boats are known as salties.
One of the more common sights on the lakes is the 1,000‑by‑105 foot (305-by-32 m), self-unloader. This is a laker with a conveyor belt system that can unload itself by swinging a crane over the side. Today, the Great Lakes fleet is much smaller in numbers than it once was because of the increased use of overland freight, and a few larger ships replacing many small ones.
In 2002, 162 million net tons of dry bulk cargo were moved on the Lakes. This was, in order of volume: iron ore, grain, and potash. The iron ore and much of the stone and coal are used in the steel industry. There is also some shipping of liquid and containerized cargo but most container ships cannot pass the locks on the Saint Lawrence Seaway because they are too wide. The total amount of shipping on the lakes has been on a downward trend for several years.
Recreational boating and tourism are major industries on the Great Lakes. A few small cruise ships operate on the Great Lakes including a couple of sailing ships. Sport fishing, commercial fishing, and Native American fishing represent a US$4 billion a year industry with salmon, whitefish, smelt, lake trout, and walleye being major catches.
The Great Lakes are used to supply drinking water to tens of millions of people in bordering areas. This valuable resource is collectively administered by the state and provincial governments adjacent to the lakes.
|Ship's Name||Year Built||Nationality||Ship's Name||Year Built||Nationality||Ship's Name||Year Built||Nationality|
|Niagara (palace steamer)||1856||United States||SS Christopher Columbus||1892||United States||SS Eastland||1902||United States|
|Milwaukee Clipper||1904||United States||SS Keewatin||1907||Canadian|
Two notable ships that have sunk on the Great Lakes are the SS Edmund Fitzgerald and Le Griffon. The SS Edmund Fitzgerald, which sank November 10, 1975, was the last major freighter lost on the lakes, sinking just over offshore from Whitefish Point in Lake Superior.
In August 2007, the Great Lakes Shipwreck Historical Society announced that it had found the wreckage of Cyprus, a long, century-old ore carrier. Cyprus sank during a Lake Superior storm on October 11, 1907, during its second voyage while hauling iron ore from Superior, Wisconsin, to Buffalo, New York. The entire crew of 23 drowned, except one, a man named Charles Pitz, who floated on a life raft for almost seven hours.
In June 2008 deep sea divers found the wreck of the 1780 Royal Navy warship, HMS Ontario in Lake Ontario and has been described as an archaeological miracle. There are no plans to raise her as it is being treated as a war grave.
A preliminary health risk assessment stated that the "proposed training will result in no elevated risks for a freshwater system such as the Great Lakes using 'realistic worst case' assumptions, and further investigation is not recommended ... if typical rather than worst case assumptions were used, the predicted risk would be even less. However, the assessment was based on lead levels after five years, and so one could infer that lead levels could meet or exceed EPA safe levels for lead after fifteen years. The Coast Guard established an information page about their proposal at http://www.uscgd9safetyzones.com
On December 18, 2006, the Coast Guard announced its decision to withdraw the entire proposal. Officials said they would look into alternative ammunition, modifying the proposed zones and have more public dialogue before proposing a new plan.
The bill states that "the Great Lakes are on the brink of an ecologic catastrophe" and that "if the pattern of deterioration is not reversed immediately, the damage could be irreparable". It cites the closing of over 1,800 beaches in 2003, the dead zone in Lake Erie, and the US$500 million damage each year due to the zebra mussel as evidences that "a comprehensive restoration of the system is needed to prevent the Great Lakes from collapsing".
A press release states that the bill aims to stop the introduction and spreading of invasive species, prevent the Asian carp from invading the Great Lakes, phase out mercury, restore animal habitats, and prevent sewage contamination.
A coalition called Healthy Lakes, Healthy Lives was formed by several environmental groups and foundations in 2005 to educate and assist citizens in advocating for the cleanup of the Great Lakes.
Similarly, there has been interest in making Lake St. Clair a Great Lake. In October 2002, backers planned to present such a proposal at the Great Lakes Commission annual meeting, but ultimately withheld it as it appeared to them to have too little support.
By 1801, the New York Legislature found it necessary to pass regulations curtailing obstructions to the natural migrations of Atlantic salmon from Lake Erie into their spawning channels. In the early nineteenth century, Upper Canada's government found it necessary to introduce similar legislation prohibiting the use of weirs and nets at the mouths of Lake Ontario’s tributaries. Other protective legislation was passed as well, but enforcement remained difficult and often quite spotty.
On both sides of the Canada–United States border, the proliferation of dams and impoundments multiplied, necessitating more regulatory efforts. The decline in fish populations was unmistakable by the middle of the nineteenth century, as the obstructions in the rivers prevented salmon and sturgeon from reaching their spawning grounds. The decline in salmon was recognized by Canadian officials and reported as virtually a complete absence by the end of the 1860s. The Wisconsin Fisheries Commission noted a reduction of roughly 25 percent in general fish harvests by 1875. Many Michigan rivers sport multiple dams that range from mere relics to those with serious loss of life potential. The state's dam removal budget has been frozen in recent years; in the 1990s, the state was removing 1 dam per year.
Overfishing was cited as responsible for the decline of the population of various whitefish, important because of their culinary desirability and, hence, economic consequence. Moreover, between 1879 and 1899, reported whitefish harvests declined from some 24.3 million pounds (11 million kg) to just over 9 million pounds (4 million kg). Recorded sturgeon catches fell from 7.8 million pounds (1.5 million kg) in 1879 to 1.7 million pounds (770,000 kg) in 1899. The population of giant freshwater mussels was eliminated as the mussels were harvested for use as buttons by early Great Lakes entrepreneurs.
There were, however, other factors in the population declines besides overfishing and the problems posed by water obstructions. Logging in the Great Lakes region removed tree cover near stream channels which provide spawning grounds, and this affected necessary shade and temperature-moderating conditions. Removal of tree cover also destabilized soil, allowing soil to be carried in greater quantity into the streambeds, and even brought about more frequent flooding. Running cut logs down the Lakes’ tributary rivers also stirred bottom sediments. In 1884, the New York Fish Commission determined that the dumping of sawmill waste (chips and sawdust) was impacting fish populations.
The Great Lakes are international, and in situations that require regulation, a lack of cooperation between the U.S. and Canada might be predicted to have disastrous consequences. In the development of ecological problems in the Great Lakes, it was the influx of parasitic lamprey populations after the development of the Erie Canal and the much later Welland Canal that led to the two federal governments attempting to work together – which proved a very complicated and troubled road.
Nevertheless, despite the ever more sophisticated efforts to eliminate or minimize the lamprey, by the mid 1950s the lake trout populations of Lakes Michigan and Huron were reduced by about 99%, with the lamprey deemed largely to blame. This led to the launch of the bi-national Great Lakes Fishery Commission.
Other ecological problems in the Lakes and their surroundings have stemmed from urban sprawl, sewage disposal, and toxic industrial effluent. These, of course, also affect aquatic food chains and fish populations. Some of these glaring problem areas are what attracted the high-level publicity of Great Lakes ecological troubles in the 1960s and 1970s. Evidence of chemical pollution in the Lakes and their tributaries now stretches back for decades. In the late 1960s, the recurrent phenomenon of the surface of river stretches (see Ohio’s Cuyahoga River) catching fire from a combination of oil, chemicals, and combustible materials floating on the water’s surface, came to the attention of a public growing more environmentally aware. Another aspect that caught popular attention was the “toxic blobs” (expanses of lake bed covered by various combinations of such substances as solvents, wood preservatives, coal tar, and metals) found in Lake Superior, the St. Clair River, and other portions of the Great Lakes region.
According to the authoritative bi-national source The Great Lakes: An Environmental Atlas and Resource Book, "only pockets remain of the once large commercial fishery."
The annual Great Lakes Bioneers Conference held in Traverse City, Michigan addresses many of these problems with local speakers, workshops and tools. The conference is a satellite conference of the Bioneers Conference in San Rafael, California. The Traverse City site focuses on durable ecological and socially just solutions to a diverse set of issues in the Great Lakes bioregion.
One such infestation in the Great Lakes was the introduction of the zebra mussel, which was first discovered in 1988. The mollusk is an efficient feeder, competing with native mussels. It also reduces available food and spawning grounds for fishes. The zebra mussel also hurts utility and manufacturing industries by clogging or blocking pipes. The U.S. Fish and Wildlife Service estimates that the economic impact of the zebra mussel will be about $5 billion over the next decade.
Approximately 10 percent of nonindigenous aquatic species introduced into the Great Lakes have had significant impacts, both economic and ecological. The remaining 90 percent have potentially harmful impacts but are insufficiently researched and understood. Besides the zebra mussel, several other species have been particularly harmful. The invasion of the sea lamprey, a parasite that attaches to large fishes with a sucker mouth armed with teeth that consume flesh and fluid from its prey, has resulted in substantial economic losses to recreational and commercial fisheries. Protection of the Great Lakes fishery (both native and nonindigenous species) from sea lamprey predation has required annual expenditures of millions of dollars to finance chemical control programs.
Alewife, introduced through the canal systems built in the Great Lakes, littered beaches each spring and altered food webs, causing increased water turbidity. These impacts subsided with the intentional introduction of salmonids that were stocked as predators to keep alewife populations under control. The ruffe, a small percid fish, became the most abundant fish species in Lake Superior's St. Louis River within five years of its detection in 1986. Its range, which has expanded to Lake Huron, poses a significant threat to the lower lake fishery. Five years after first being observed in the St. Clair River, the round goby can now be found in all of the Great Lakes. The goby is considered undesirable for several reasons: It preys upon bottom-feeding fishes, overruns optimal habitat, spawns multiple times a season, and can survive poor water quality conditions.
Several species of water fleas have accidentally been introduced into the Great lakes such as Bythotrephes cederstroemi and the Fishhook waterflea potentially having an effect on the zooplankton population. Several species of crayfish have also been introduced that may contend with native crayfish populations An electric fence has been set up across the mouth of the Great Lakes across the Chicago Sanitary and Ship Canal in order to keep several species of invasive Asian carps out of the area. These fast-growing planktivorous fishes are thought to have the potential to cause substantial ecological damage to the Great Lakes, through changes in the food chain and water quality.