120 TI1E GEOLOGY OF MINNESOTA. 



[Surface configuration. 



upon the rocky surface, only a few angular fragments of the rock of the 

 country, and of weathered chert being embraced in its lowest parts; but 

 toward the west it overlaps the till, and its distinctive features gradually 

 fade out as those of the till increase. The waters that drain it are chalyb- 

 eate and calcareous, never alkaline, and the soils it forms vary from a fine, 

 stoneless clay to a sandy loam. It makes red brick and pottery, while 

 those made from the clay of the Red river valley are cream-colored. Be- 

 sides these large areas covered by stratified clay, which may be taken as 

 types, there are numerous smaller areas scattered through the interior of 

 the state, evidently dependent upon the former or present operation of 

 a large stream or lake, which belong to one or the other kind, but also 

 sometimes exhibit a union of the chemical and physical characters of both. 

 Such occur in Carver, Hennepin, Anoka, Meeker, Wright, Blue Earth and 

 Crow Wing counties, and in several others. There is also about the west 

 end of lake Superior a bright red stratified clay, seen at Duluth, and rising 

 to the hight of about 450 feet above the lake. This seems to have been 

 spread by the waters of lake Superior when they stood about 500 feet 

 higher, though probably carried into the lake by the St. Louis and other 

 streams from the red till which characterizes the drift of that district. 



III. THE SURFACE CONFIGURATION OF DIFFERENT PARTS OF THE STATE. 



The only part of Minnesota that may be styled mountainous is in the 

 northeastern triangle included between the international boundary line, 

 lake Superior and Vermilion lake; and much of this is heavily drift-covered, 

 with a moderately rolling or undulating surface. But there are mountain 

 peaks along the shore of lake Superior, and in the northern part of Cook 

 and Lake counties that rise from 1600 to 1800 feet above the level of the 

 ocean. There are also hill ranges or mountains, particularly those known 

 as the Sawteeth, the Mesabi and the G iant's ranges, which maintain a broken 

 outline, consisting of crystalline rock, and rising from 1200 to 1500 feet 

 above lake Superior, or about 2000 feet above the sea. Westward from this 

 mountainous tract the state shows moderate undulations of level, which 

 primarily are due probably to the general contour of the rocky surface; but 

 as the immediate surface is composed of drift, the configuration is dependent 

 on the manner of deposition and accumulation of the surface materials. 



