130 THE GEOLOGY OF MINNESOTA. 



[Lakes and rivers- 







operated to calcine and disintegrate the few stones of the till which hap- 

 pened to be within their reach. 



VI. THE LAKES AND RIVERS, AND THE QUALITIES OF THE WATEKS 

 OF THE DIFFERENT PORTIONS. 



Lakes. The number of lakes in Minnesota is about ten thousand. 

 These can be divided into three classes based on their origin and topo- 

 graphical surroundings; but the classes fade into each other along the 

 boundaries of the areas containing them, in proportion as the elements that 

 go to make up their characteristics become less powerful and are replaced 

 by others. Sometimes a large lake partakes of the characters of two or of all 

 these classes, like Mille Lacs, and like lake of the Woods. 



1. Lakes of the morainic till areas. 



2. Lakes of the modified drift areas. 



3. Lakes of the areas of bare rock. 



Lakes of the morainic till areas. This is by far the most numerous and 

 important class, embracing more than three-fourths of all the lakes in the 

 state. The most remarkable and characteristic of these areas is that known 

 as the Leaf hills or park region in Becker and Otter Tail counties, where 

 the lakes are so numerous that to the observer one-half of the surface seems 

 to be covered by water. This area, however, extends northward and south- 

 ward, and in some other parts of its development it shows almost an equal 

 profusion of small, deep lakes. This is true in some parts of Douglas, Carver, 

 Hennepin and Le Sueur counties. This belt of lakes crosses the state to the 

 Iowa line, including much of Scott, Le Sueur, and Freeborn counties, and 

 the western portions of Dakota and Rice counties. It does not show so 

 many lakes in Waseca and eastern Blue Earth. Toward the north and east 

 this series of lakes, though less remarkable, includes the region of Itasca 

 lake, Turtle lake and the " Julian sources " of Beltrami, the lakes that feed 

 the Big Fork river, flowing northward, as well as those that are drained 

 southward by the Mississippi, the Prairie and Swan rivers. Toward the 

 east further it accompanies the Mesabi range, and supplies the numerous 

 streams that enter lake Superior, terminating in the Indian reservation 

 near Pigeon point, where some of its lakes exhibit also some of the char- 

 acters of Class No. 3. This belt of lakes varies in width from ten to fifty 



