The ice sheets float atop the mantle

The Great Lakes of North America It is an astonishing yet true fact that the Great Lakes are freshwater systems that make up an estimate of 20 percent of the world’s current surface freshwater that is available to us. Whenever one is in the state of Michigan, one is never more than 85 miles away from at least one of the Great Lakes.

There are also 3,288 miles worth of Great Lakes towards the coastline which also happens to be a shoreline with the freshest water around the globe.  The total surface area of the major 5 lakes is 95,000 square miles and can hold an estimate of 5,500 cubic miles of water. Formation of Great Lakes and Isostatic ReboundIt is important to look and understand how the Great Lakes came to be. The Great Lakes came to be during the Pleistocene Epoch. They are in fact a direct outcome of glaciers advancing as well as retreating in size over the course of thousands of years. A lake that has come into existence with the help of a glacier is known as a glacial lake.

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When great ice sheets erode the land and fill up spaces. The large ice sheets float atop the mantle of the Earth which is the molten layer underneath the crust. The glacier sheets are so heavy that they push Earth’s crush down with their weight. When the glaciers retreat back and the crust of the Earth slowly recovers. The process of recovery is slow and the crust can recover as little as a centimeter in every century.

The technical name for this process is isostatic rebound.  The land that is then a part of erosion is carefully deposited with the help of glaciers as they advance or retreat. This process or rather this eroded land is referred to as moraines which is what ends up making the very boundaries of the Great Lakes. There are many processes that have contributed along several great years towards the making of the Great Lakes, several lake stages that surround the Great Lakes Basin. There are many prehistoric lakes, one may consider.

The list includes lakes like Lake Algonquin, Lake Nippising and Lake Chippewa. Climate and Economic ValueThe current visibility available of the five Great Lakes show that they contain an estimate of six quadrillion gallons in terms of water, while the ice caps as well as Lake Baikal contain much more water that is yet to be melted. Among all of the five Great Lakes, it is Lake Superior that has the steepest point as it has the depth point of 1,333 feet. The Great Lakes are mighty unique in the way that all of their lake basins are linked with one another and they then go on to form a continuous as well as steady water drainage basic which is an estimate of 2,212 miles. This continuous and steady part is also imperative for shipping purposes as it provides traders direct route to the Atlantic Ocean through the help of the St. Lawrence Seaway.

Wisconsin DrainageThere has been a lot of debate on the authenticity of the area that surrounds the Great Lakes found in the North America are glaciated or not. The debate that can in fact be reported focuses greatly on the area and the features found around the lakes, this may include the drainage patterns of the regions prior to the Wisconsin Glaciation. In order to understand this, we must take a look at the stages of drainage that combine one another in order to form the lake systems currently present. The modern drainage system and pathway for the region in question here contains within itself a watershed that closely follows and encompasses not only the peninsulas found in Michigan but also that of western Wisconsin, Minnesota and even the extreme northern regions of Indiana, Southern Ontario, New York, as well as the state of Ohio. Water Path into The Great LakesThe river streams from all of these areas then flow right into and drain into major 5 lakes of the Great Lakes.

From these Great Lakes, the water then goes on to flow into St. Lawrence River and then right on to the Atlantic. The water then drained from both Lakes Superior as well as Michigan goes on to flow directly in to Lake Huron with a path constructed through St. Mary’s River which is a Superior lake and then right into Straight of Mackinac which is a Michigan Lake. After this point, the water flows into Lake Erie via a path through St. Claire as well as the Detroit Rivers.

This water that is drained also contains water flowing from the Georgian Bay. Lake Eerie continues to drain into the Niagara River and then Lake Ontario and its final resting places are the Atlantic Ocean via a path from St. Lawrence River. Before the advancements made by Wisconsin Glacier, and the drainage ice used to flow just about the same path as it used to in the past. The only factor that differentiates is that the glacier has made is the connection through the lakes Huron, Eerie, St. Claire as well as the Detroit Rivers. Wildlife Found Near The Great LakesThe Great Lakes contain not one but five freshwater lakes that are located not only in North America but also in the United States and along the border of Canada. These lakes support a great deal of diverse fauna that includes birds, reptiles, fishes, mammals and amphibians.

One can find up to 250 unique kinds of fishes in the regions that includes salmon, bluegill, brook trout, Coho salmon, freshwater drum, Chinook salmon, lake sturgeon, whitefish, rock bass, walleye, northern pike, and several others. As far as native mammals are concerned, black bear, fox, elk, moose, beaver, white-tailed deer, rover otter, coyote, Canada lynx and gray wolf are not impartial to living in the areas that surround the 5 Great Lakes. Native Plants Found Near The Great LakesWhite Pine (Pinus Strobus)While the Great Lakes are hospitable to a great deal of wildlife, the plants have made their own homes nearby.

White pine is locally found in the Michigan state and is also known to be the tallest conifer in the whole of the northeastern United States. The needles of this conifer are soft and are in the colors bluish-green to silver green and are found to locally be in the bundles of five or more. Blue VioletThese are beautiful blue violet plants that are usually found all over the Great Lakes basin. They are locally a Minnesota and Illinoi state flowers.

Their colors vary from white to lilac to blue to yellow as well as even green sometimes. There are other plants such as the White Oak that are more common but the list of rare plants found near the Great Lakes are Houghton’s Goldenrod, American Chestnut and many more. Economic and Political View of the Great LakesAgricultural Value of Lands Near The Great LakesMany settlers were attracted towards the Great Lakes due to the agricultural value the lands there hold. As the years went by, the local production for both dairy as well as meat ended up becoming the more dominant agricultural factor of the lands. This demand later expanded into vegetables, fruits as well as tobacco.

Commercial and Sport FisheriesWhen the Great Lakes are concerned, the commercial as well as the sports fisheries play an important role. These practices began around the year 1820 and have only continued to increase since then. A shocking 65 million pounds of fish are caught from the lakes that ends up contributing an estimate of more than $1 billion into the economy. The fishes listed earlier on that are found in the Great Lakes are the fish that majorly contribute to the economy upon being caught. Sports fishery is a major tourist attraction for people all over the world and it continues to bloom the economy near the Great Lakes.

It contributes a total of $4 billion to the economy. Tourism and IndustryIt is no secret that the Great Lakes prove to be a great and popular tourist attraction. The region contains several parks, wilderness areas and conservations along with many beaches that the tourists can enjoy. Activities such as fishing, diving and boating only make up for a few along many that can be found on the list of things a tourist can partake in while visiting the Great Lakes. People began to industrialize the Great Lakes at the turn of the 20th century. It did more harm than good to the environment due to early industrialization. But there are many people who would argue otherwise. Over the many years, the industries along the Great Lakes have not only produced steel, but also paper, chemicals, manufactured goods as well as automobiles.

But it was the production and manufacturing of steel that started it all. Moving back into the discussion of the Great Lakes and the specifics!The First LakesThe advancements of the Wisconsin glacier could be seen progressing through several major lobes within the region. They were initially caused by outcrops of bedrock that was highly resistant in the current Keweenaw, Door as well as Bayfield Peninsulas. (National Park Service, 2004)Along the western region could be found the Des Moines lobe which moved from the north-northwestern along to the south-southwestern as it formed a path through Minnesota as well as Iowa. It was the Langlade Lobe, Green Bay Love as well as the Lake Michigan Love that continued to follow close by in relatively parallel paths along south-southwestward towards Ontario, crossing across the Superior as well as Michigan basins and landing right into Wisconsin, Illinoi as well as several parts of Iowa. It was the Ontario Lobe that gradually advanced southwards while connecting through St.

Lawrence water shed and down right into the western New York as well as the Pennsylvania. (Bauder, 2004) The Saginaw and the Huron-Eerie however, flowed right in the middle of Ontario as well as Michigan Lobes right towards the southwest. (Farrand, 1988)              The Surface RocksThe surface rocks near the Great Lakes region were relatively soft and could be referred to as Paleozoic shales, salts as well as sandstones which were the reason for cutting of drainage of the river valleys.

These valleys provided a path for the ice to carefully follow through. The ice continued to divide into major loves and then eroded the soft rocks. It then kept following the major river valleys at the time. These rover valleys widened with the pressure as well as deepened whereas on the side, the tributary valleys quietly destroyed.

(Farrand, 1988) The ice then formed its path out of the St. Lawrence watershed and lowed into the Mississippi watershed but remained clear and stopped short right at the mouth of Ohio River. The Upper Great LakesThe upper Great Lakes which are lakes Michigan, Lake Huron and Lake Superior went through stages in which they contained low water levels which was directly connected to the advance as well as retreat of the glaciers they were receiving most of their freshwater from in the basin. Lake Chicago was almost forced out of its banks when the border of the lake advance about 500 years after the lake was formed in the location. After the advancements of the Port Huron, the ice retreated back above the Straits of Machinac and continued to expose a lower outlet in Ontario based in Kirkfield. This outlet gave way right into the Trent Valley from the Georgian Bay as well as gave passage into the Lake Ontario. The ice didn’t stop but continued to retreat revealing more and more lower outlets across Ontario connecting through the Ottawa River as well as the North Bay. However this retreat in ice levels reduced the water level in Lake Stanley which is in the Huron Basin.

This made it so that the water drained from Lake Chippewa which is in the Michigan Basin to continue on through the Mackinac River. (Hansen, 1999) To conclude, it can be understood that the Great Lakes of Northern America prove to be of great importance to the economy as well as the wildlife. There are exotic plants as well as creatures that thrive here. They are a result of glaciers melting and will always be the 5 biggest freshwater lakes that bring in a lot to the economy with the fishes as well as the tourism they continue to bring. What we do need to do however is put a limit on the fishing whether it is for sport or for commercial use so that the wildlife can continue to thrive in the Great Lakes and also continue to bring in a lot of money into the economy along with more freshwater than can be found anywhere else in the world.  ReferencesFarrand, W.

R. 1988. Glacial Lakes around Michigan. Geological Survey Division, Michigan Department of Environmental Quality, Bulletin 4Bauder, A. 2003.

SLIP – Ice Sheet Modeling, Southern Laurentide Ice-sheet Project. World Wide Web homepage URL:

html Retrieved on: Novber 13, 2004.National Park Service. Ice Age Scenic Trail. World WIde Wibe homepage URL:  Retreived October 13, 2004.

Hansen, M. C. 1999. History of Lake Erie. Ohio Department of Natural Resources, Geological Survey Division.

World Wide Web homepage URL: Retrieved on November 23, 2004.


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