Clair and the next lowest lake. Lake Erie. Lake Erie discharges into Lake 

 Ontario through Niagara River, in the course of which the water passes over 

 Niagara Falls. St. Lawrence River carries the water of Lake Ontario to the 

 sea. 



In common usa,,e the term Great Lakes is restricted to the five largest 

 lakes, because of the relatively insignificant size of Lake St. Clair. Lake 

 St. Clair may be regarded merely as an expansion of the river connecting Lake 

 Huron and Lake Erie. 



Of the five Great Lakes, Lake Erie exceeds only Lake Ontario in area.-^ 

 Including; Detroit River, its area is 9,9^^0 square miles (25,7U5 square kilo- 

 meters) , and the International Boundary divides the lake in almost exactly 

 equal parts (Fig. 2). The entire draina-;e basin has an area of 3U,680 square 

 miles (89,821 square kilometers). The greatest length of the lake, along a 

 straight line clearing point Pelee and Long Point is 2Ul miles (388 kilometers) 

 and the greatest breadth, between Ashtabula and Point Talbot, is 57 miles (92 

 kilometers). The principal axis of the lake has an approximately ENE-wSW trend 

 for most of its length, but west of Point Pelee the trend is nearly ESE-'aNW. 



The southern shore is remarkably regular, with Ottawa Peninsula and 

 Sandusky Bay toward the west, and Presque Isle toward the east as the only 

 notable feat-ures. On the north there are three proimnent peninsulas to 

 break the monotony of the otherwise regular shore line. They are Point 

 Pelee on the west, Pointe aux Pins some miles eastward, and Long Point near 

 the east enc of the lake. Point Pelee and Long Point are so prominent that a 

 map of the lake naturally divides itself in t!-Tee sections; a large central 

 section, with smaller sections at either end. The shores are low for the most 

 part, especially near the west end. Although the number of tributary rivers 

 is large, only one, Detroit River, is important in the amount of discharge. 

 The western half of the northern shore has very few streams entering the lake. 

 At the extreme eastern end, the lake discharges into the Niagara River, which 

 carries the water northward to Lake Ontario. For an account of the topography 

 of the shores, and the underlying geological structures, the reader is 

 referred to Leverett (1902) and to Pegrum (1929). 



Lake Erie is the shallowest of the five Great Lakes and the only one 

 w'ose bottom does not extend below sea level. The deepest point recorded is 

 210 feet (6I4 meters) below standard low water (570.00 feet (173.78 meters) 

 above mean sea level), which has been adopted for the charts of Lake Erie 

 issued by the United States Lake Survey. The mean lake level during the 

 period I86O-I93O was 2.UIi feet (0.7Uii meter) above standard low water, hence, 

 soundings made on the lake will normally be greater than those recorded on 

 the charts. The division of the lake into three sections, which is so evir 



1/ A detailed description of Lake Erie, as well as of the other lakes of the 

 St. Lawrence River system, appears annually in a bulletin entitled "Survey 

 of Northern and Northwestern Lakes", published by the United States Lake 

 Survey, at Detroit. The hydrographic data given here aire taken from Bulle- 

 tin No. I4O, published in 1931, and from charts issued by the Survey. 



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