58 



LAKES OF NOKTH AMERICA. 



determined from thousands of soundings, is also indicated. This excellent 

 survey is the basis of nearly all accurate information now accessible con- 

 cerning the physical features of the lakes in question, and has been freely 

 used in compiling the following statements. 



Owing to changes in the rivers connecting the various Laurentian 

 lakes and in bays and navigable channels, and also on account of the 

 many harbor and canal improvements that have been made, a new survey 

 of portions of these lakes has been found necessary, and is now in prog- 

 ress under the direction of Gen. (). M. Poe. 



The area of the Laurentian lakes has been determined with approxi- 

 mate accuracy from measurements made on the maps of the U. S. Lake 

 Survey. The results of these measurements by different individuals 

 vary somewhat, but those published by L. Y. Schermerhorn^ are here 

 adopted. 



Area of the Laurextian Lakes ix Square Miles. 



Lake Superior 



St. Mary's river 



Lake Micliigan 



Lake Huron and Georgian Bay 



St. Clair river 



Lake St. Clair 



Detroit river 



Lake Erie 



Niagara river 



Lake Ontario 



Total 



Water Sur- 

 face. 



31,200 



150 



•22,4.50 



23,800 



25 



410 



25 



9,960 



15 



7,240 



95,275 



Water Shed. 



51,600 

 800 



37,700 



31,700 

 3,800 

 3,400 

 1,200 



22,700 

 300 



21,600 



174,800 



Hydrographic 

 Basin. 



82,800 

 950 



60,150 



55,500 

 3,825 

 3,810 

 1,225 



32,660 

 315 



28,840 



270,075 



The volume of water flowing through the rivers draining the various 

 lakes is on an averasfe as follows : 



St. Mary's river, the outlet of Lake Superior 



St. Clair river, the outlet of Lakes Huron and Michigan 



Niagara river, the outlet of Lake Erie . . 



St. Lawrence river, the outlet of Lake Ontario 



Cubic Feet 

 PER Second. 

 86,000 

 235,000 

 265,000 

 300,000 



1 "Physical Features of the Northern and Northwestern Lakes," Amer. Jour. Sci., 3d 

 sec, vol. .33, 1887, pp. 278-284. 



