GENERAL PHYSICAL FEATURES. 13] 



Lakes and rivers.] 



miles, and embraces Leech and Winnibigoshish lakes, two of the largest 

 lakes of the state, though they do not perfectly illustrate the lakes of the 

 first class. Lake Minnetonka, in Hennepin county, is most perfectly typical 

 of the lakes of this class. 



The lakes of the Coteau des Prairies which crosses the southwestern 

 corner of the state Irom Lincoln county to Jackson county, belong to the 

 first cliiss, but they are not so thickly spread over the country as those of 

 the central part of the state. Another important area of till-based lakes 

 stretches southeastward from Leech lake to Mille Lacs, and another from 

 Ramsey county northward to southern Pine county. The lakes of the last 

 area, however, are not characteristically based on rolling till, but frequently 

 involve the features of the second class. 



Lakes of the modified drift areas. These are found in the level or undu- 

 lating portions of the state where the till, which is usually the material 

 which confines their waters, is superficially covered with stratified clay 

 or sand and gravel. They are comparatively rare, and usually shallow, but 

 they constitute the largest lakes of the state. Red lake belongs to this class, 

 being the largest in Minnesota, containing about 340 square miles. The 

 northern shores of Leech lake, and the southwestern of the lake of the 

 Woods exhibit the characters of this class. Such lakes are scattered sparsely 

 over the central portions of the state in Cass and ^adena and in southern 

 St. Louis counties. Some of those in northern Ramsey are lakes of this 

 character. 



Lakes of the areas of bare rock. These have rocky basins, and are due 

 to the immediate contour of the rocky surface. The lakes of the northern 

 boundary of the state, from the west end of Rainy lake to lake Superior, 

 and the numerous clear lakes that lie on either side of the boundary, illus- 

 trate this class. The surface has been subjected to severe glaciation, but 

 for some reason the drift is almost wholly wanting. The lakes take the 

 shapes of the depressions of the rocky contour. They are very numerous, 

 with tortuous and bold shores. They are connected by lively streams that 

 have frequent rapids and cascades. There are here no deep rock-gorges 

 cut by drainage courses, but the surface is that left by the glacier, and the 

 water simply gets from one basin to another by filling them up and over- 

 * running their rims. Lake Superior itself is a stupendous example of the 



