Physical Features of Great Lakes

The Great Lakes are a group of five large freshwater lakes in central North America, interconnected by natural and artificial channels. From west to east they are Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario. Lake Michigan lies entirely within the United States; the others form part of the border between the United States and Canada. The combined surface area of the lakes is 244,100 sq km (94,250 sq mi). Together the lakes drain a total of about 750,000 sq km (about 290,000 sq mi) in Canada and the United States. The primary outlet of the system is the St. Lawrence River; a portion is diverted from Lake Michigan to the Chicago River. The lakes are bordered by the Canadian province of Ontario and by eight U.S. states: New York, Pennsylvania, Ohio, Indiana, Michigan, Illinois, Minnesota, and Wisconsin.

The Great Lakes are a natural resource of tremendous significance in North America, serving as the focus of the industrial heartland of the continent. Together they hold about 20 percent of the world's fresh surface water. Four of the 20 largest cities in North America (Chicago, Detroit, Toronto, and Cleveland) lie on the shores of the Great Lakes system and owe much of their wealth to commerce attracted to the lakes. The lakes also form an important recreational resource with about 17,000 km (about 10,500 mi) of shoreline, rich sport fisheries, and numerous beaches and marinas.

The beaches of the Great Lakes are some of the best in the world and add considerably to the recreational attraction of the state. Inland from the beaches, there are often beautiful sand dunes, a distinctive feature of the topography of Michigan, particularly along the eastern shore of Lake Michigan. Recently, a problem has developed in the level of the water in the western Great Lakes surrounding the state of Michigan. The level fluctuates from 1 to 2 m over a period of years because of the amount of precipitation and runoff received. In the 1970s, a near all-time high of nearly a meter above the mean level was reached by Lakes Huron and Michigan, and considerable lakeshore damage occurred as a result.
    Although individual owners as well as certain cities and villages along the shore are developing piers, breakwaters, groins, and seawalls of various kinds to protect the shore, high-water erosion and flood damage still threaten the shoreline. The erosive power of a fall or spring storm on Lake Michigan, Lake Superior, or Lake Huron is awesome. The Army Corps of Engineers is studying the problem of fluctuating lake levels, but there are no easy solutions. One possible remedy is to allow more water to go out through the southern end of Lake Michigan (i.e., be diverted from the basin), via the Chicago River, and on into the Mississippi River. However, it is estimated that this action would have only a minor effect on the problem. Another suggestion has been made that the outlet near the St. Clair and Detroit Rivers--and further, the Niagara River, which is the outlet of Lake Ontario--be lowered so that the volume of water that can flow out through the St. Lawrence River would be increased. This may be more effective solution, but it would take a great deal of coordination between the different states involved, as well as the cooperation of Canada.

 

Physical Features Lake Superior Lake Michgan Lake Huron Lake Erie Lake Ontario Total
Elevation        (feet)
                  (meters)
600 
183
577 
176
577 
176
569 
173
243 
  74
 
Length          (miles)
                        (km)
350 
563
307 
494
206 
332
241 
388
193 
311
 
Breadth         (miles) 
                        (km)
160 
257
118 
190
183 
245
57 
92
53 
85
 
Ave. depth     (feet) 
                  (meters)
483 
147
279 
85
195 
  59
62 
19
283 
  86
 
Max. depth    (feet) 
                  (meters)
1,332 
   406
925 
282
750 
229
210 
  64
802 
244
 
Volume        (miles3) 
                       (km3)
  2,900 
12,100
1,180 
4,920
   850 
3,540
   116 
1,640
393 
  22
  5,439 
22,684
Water area  (miles2) 
                       (km2)
31,700 
82,100
22,300 
57,800
23,000 
59,600
  9,910 
25,700
  7,340 
18,960
94,250 
244,160
Watershed   (miles2)                          (km2)   49,300 
127,700
  45,600 
118,000
  51,700 
134,100
30,140 
78,062
24,720 
64,030
201,460 
521,830
Total area     (miles2) 
                       (km2)
  81,000 
209,800
  67,900 
175,800
  74,700 
193,700
  40,050 
103,700
32,060 
82,990
295,710 
765,990
Retention Time (yrs) 191 99 22 2.6 6  
Outlet St. Marys River Straits of Mackinac St. Clair River Niagara River/ Welland Canal St. Lawrence River  

Lake Superior, the largest in area of the Great Lakes at 82,100 sq km (31,700 sq mi), is the largest freshwater lake in the world. Of the Great Lakes, Lake Superior is the highest above sea level, at 183 m (600 ft), the farthest north, and the coldest. Its outlet is the Saint Marys River, which enters Lake Huron after falling about 7 m (about 21 ft) over a series of rapids between the twin cities of Sault Sainte Marie, in Ontario and Michigan.

Lake elevations decrease to the south and east. Lake Huron and Lake Michigan lie at the same elevation, 176 m (577 ft), separated by the Straits of Mackinac, where water flows from Lake Michigan to Lake Huron. Huron is the larger of the two in area, at 59,600 sq km (23,000 sq mi); Michigan is deeper, 85 m (279 ft) on average, and contains more water. Both Michigan and Huron have numerous islands, the largest of which are contained in the Manitoulin Islands chain in Lake Huron. At its southern end, Lake Huron drains into the Saint Clair River, which falls about 3 m (about 9 ft) between Lake Huron and the small, shallow basin of Lake Saint Clair.

The Detroit River connects Lake Saint Clair with Lake Erie. At its northeast end, Lake Erie empties into the Niagara River, which drops 99 m (325 ft) as it flows north to Lake Ontario. Lake Ontario, the smallest of the Great Lakes at 19,010 sq km (7340 sq mi), is the 14th largest lake in the world. The outlet of Lake Ontario is the St. Lawrence River. 

 

Parts of this page are from the Encarta Encyclopedia: www.encarta.msn.com

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