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Abstract
This present paper explores the process of formation of the Lake Erie basins that were conditioned by glaciers. Glacial erosion which carved out the lake beds and the subsequent deposition of huge amounts of sediment led to the formation of the eastern, central, and western basins of Lake Erie. In addition, the geologic composition of Lake Erie is included in the present investigation.
Introduction
“The Great Lakes” is the joint name for the five following lakes: Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario. The case states that the group measures even more than 750 miles from east to west, and the fragments of the Great Lakes are located in Minnesota, Wisconsin, Illinois, Indiana, Michigan, Ohio, Pennsylvania, New York, and Ontario, Canada (par.1). The value and the importance of the Great Lakes can be explained by many factors, their being the largest freshwater system in the world (with 18 percent of the freshwater supply of the world) is among them (Case par. 1). A fact that contributes to the overall importance of the Great Lakes is that, if taken together, they provide drinking water for the population of forty million people in the USA and Canada (Case par.1).
Since the focus of the present paper is only one lake that belongs to the Great Lakes, Lake Erie, there is the necessity to introduce basic information pertaining to it before putting emphasis on the formation and geological composition of the lake. Lake Erie is the fourth largest of the Great Lakes and the thirteenth largest lake in the world (Case par. 9) and the world’s twelfth largest freshwater lake (University of Wisconsin Sea Grant Institute par. 1). It is 240 miles long and 30 to 60 miles wide. It is necessary to mention that Lake Erie is the only Great Lake with a bottom above sea level (Geology of the Lake and Islands par. 4). There are two specific features that characterize Lake Erie: first, its soils are considered to be the most fertile among the Great Lakes (Case par.9). Second, it tends to warm quickly in summer in comparison with the other Great Lakes, and it freezes earlier in the winter, respectively (Case par. 9). Consequently, it is the shallowest of the Great Lakes and it contains three basins: the eastern, central, and western ones. The eastern basin extends from Buffalo, New York to Erie, Pennsylvania, having an average depth of approximately 120 feet, while the central basin extends from Erie, Pennsylvania to Cedar Point, Ohio with an average depth of 80 feet (Geology of the Lake and Islands par. 4). The western basin stretches from Cedar Point to Toledo, having an average depth of only 35 feet (Geology of the Lake and Islands par. 4). The present condition and characteristics of Lake Erie are conditioned by the process of formation of Lake Erie and its geological composition that will be studied in the present paper.
Formation of the Great Lakes and Lake Erie
Pre-Wisconsin Drainage
Scientists do not argue much nowadays on the hypothesis stating that the area that surrounded the Great Lakes of North America used to be indeed glaciated (Damery par. 1). Instead of this, the contemporary discussion focuses on the main evidence of geologic importance found in the studied area, among which are the drainage patterns of this region that took place before the Wisconsin Glaciation, and the stages, gradual sequence of which predetermined the appearance of the contemporary system of the Great Lakes. Camp states that “the Wisconsinan ice sheet alone could not have cut a basin as deep as the Erie Basin, so the basin must have been a lowland before glaciations even though the thickening of ice over this low spot would have increased the ice sheet’s erosional capacity” (305). If contemporary drainage pattern for the analyzed region is considered, it is necessary to state that it includes a watershed encompassing both peninsulas of Michigan, western Wisconsin, and Minnesota as well as the extreme northern portions of Indiana, Ohio, and the New York panhandle and Southern Ontario (Damery par. 2). It is evident that the Great Lakes are the water bodies into which all rivers, as well as streams of the region, drain with their subsequent flow into the Atlantic Ocean. “Lake Erie drains through the Niagara River into Lake Ontario and then out into the Atlantic Ocean through the St. Lawrence River” (Damery par. 3). As for the flow of water in the region before the advance of the Wisconsin glacier, it can be stated that it used to adhere to a similar course. However, the main difference of Pre-Wisconsin drainage was the connection between Lakes Huron and Erie and St. Clair and Detroit Rivers (Damery par. 4). There existed the preglacial Erigan River, the significance of which for the present paper is determined by the fact that it used to flow over the land now occupied by Lake Erie. Thus, there existed preglacial valleys and they were deepened by the Pleistocene glaciers that followed them making them broader and deeper (Bolsenga and Herdendorf 51).
Climatic Factors of the Formation of the Great Lakes
As it is stated in Geology of the Lakes and Islands, it is possible to determine the approximate date of the formation of the Great Lakes, they have formed 7000 to 32000 years ago during the period called the Pleistocene Epoch, which is commonly known as the Ice Age (par. 1). As its name suggests, the temperature remained low during this period, and this factor caused accumulation of the great amounts of snow. The snow did not melt due to permanent low temperatures that resulted in the appearance of glaciers, the huge ice sheets, some of which were 10000 feet thick (Geology of the Lake and Islands par. 1). The movement of the glaciers kept southward direction until they reached the southernmost part of Wisconsin where the temperature began to rise gradually provoking the northward retreat of the glaciers (Geology of the Lake and Islands par. 2).
The Stages of Formation of Lake Erie, a Glacial Lake
A significant feature of Lake Erie is that it was the first of all the Great Lakes to appear. Due to meltwater produced by the melting glaciers and the damming of the water by Valoprasio-Fort Wayne moraines that helped to form the two Great Lakes that were the ancestors of the modern Great Lakes called Early Lake Chicago and Early Lake Maumee, the latter pooled in the Erie basin (Damery par. 11). There were two stages of the Lake Maumee, the Highest Lake Maumee and the Lowest Lake Maumee (Bolsenga and Herdendorf 57). There also existed Middle Lake Maumee, during this stage of the formation of the lake, the ice in its basin had retreated to the vicinity of Erie (Bolsenga and Herdendorf 57). The succeeding stages of the lake were as follows: Lake Arkona, Lake Whittlesey, Lake Warren, and Lake Wayne, Lake Grassmere, and Lake Lundy that was succeeded by the Early Lake Erie. During the latter period, it was established that the level of the Erie basin was controlled by the uplift of the Niagara sill (Bolsenga and Herdendorf 68). As for the stage of Middle Lake Erie, it was a phase characterized as a static one while the stage of the Highest Lake Erie or the Modern Lake Erie has been determined by the current elevation of the level to 572 ft (Bolsenga and Herdendorf 69). Besides, the uplift is still underway though it is very low nowadays.
Lake Sediments and Beach Deposits
Sediment that was carried along by the glacier was deposited in two main ways: either directly by the ice or by meltwater from the glacier (Wickstrom par. 4). It can be stated that the sediment left by the glaciers consists of mixtures of clay, sand, gravel, and boulders and as for the bedrock, it consists mainly of limestones and dolostones, and shales (Wickstrom par. 4). Capping much of the bedrock over the Lake Erie basin are deposits laid down by or associated with the younger Pleistocene glaciers (Wickstrom par. 2).
The bottom deposits of Lake Erie are built up by silt and clay muds, sand and gravel, peat, compact glaciolacustrine clays, glacial till (Bolsenga and Herdendorf 75). Sand, gravel, and glacial till build-up midlake bars, nearshore slopes, and beaches (Bolsenga and Herdendorf 75). As for the shoreline, sand deposits are limited to them (Bolsenga and Herdendorf 75).
Conclusion
Drawing a conclusion, it should be stated that the significance of Lake Erie for nature and humans can be observed on the basis of numerous facts which have been mentioned in the introductory part of the present paper. One of the Great Lakes that has been studied in this paper has proved to be unique in terms of its formation and geology. Its principal differences from the four Great Lakes are greatly determined by the process of its formation. The present state of Lake Erie is a natural consequence of the process of formation of glacial lakes.
Works Cited
Bolsenga, S.J., and Charles E. Herdendorf. Lake Erie and Lake St. Clair Handbook. Detroit, MI: Wayne State University Press, 1993.
Camp, Mark J. Roadside Geology of Ohio. Misoula, Montana: Mountain Press Publishing Company, 2006.
Case, Joy. “Great Lakes.” Our States: Geographic Treasure, 2010.
Damery, Doug. Formation of the Great Lakes. 2004. Web.
Geology of the Lake and Islands. 2010. Web.
University of Wisconsin Sea Grant Institute. Gifts of the Glaciers. 2008. Web.
Wickstrom, Lawrence H. “Glacial Map of Ohio.” Department of Natural Resources. 2010. Web.
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