TERMINAL MORAIXES. 213 



The reality of this battle of the glaciers, and of this alter- 

 nate advance and retreat of the opposing forces, is shown by 

 the succession of deposits. The lower part of the ground 

 moraine is characterized by a reddish color, and by rock- 

 fragments from the region of Lake Superior ; while the 

 upper portion, now upon the surface, is of a bluish color, 

 containing bowlders and pebbles of limestone and of creta- 

 ceous shale, and other material brought from the northwest, 

 showing that victory was first to the Lake Superior Glacier, 

 but finally to that of the Red River. 



The evidence of the junction of these two great ice- 

 streams appears clearly enough upon the surface when sec- 

 tions of country a little distance apart are considered. This, 

 Dr. G. M. Dawson had observed as early as 1875, when he 

 wrote about it thus : 



A line drawn northeast and southwest, nearly parallel with 

 the northwestern shore of Lake Superior, but lying a short dis- 

 tance back from it, and cutting the Northern Pacific Railway 

 some miles west of Thomson, in this part of Minnesota, sepa- 

 rates superficial deposits of different aspects. Northwest of 

 this line the prevailing tint of the drift material is pale yellow- 

 ish-gray, or drab ; southeast of it, reddish tints are almost 

 universal, and become specially prominent on the northern 

 part of the line of the Lake Superior and Mississippi Railway, 

 and continue to St. Paul. The junction of these two varieties 

 of drift can not, of course, be exactly defined, but is interest- 

 ing as an indication of the direction of transport of material 

 in this region : the reddish matter being derived from the red 

 rocks of the lake-shore.* 



Some other interesting things concerning the deposits of 

 this region can better be said when we come to treat of gla- 

 cial dams and lakes, and of the cause of the Glacial period. 



The surprising thing to a glacialist, upon a first visit to 



* " Report on the Forty-ninth Parallel," p. 213. See also " The Fresh-Water 

 Glacial Drift of the Northwestern States." p. 9, by Colonel Charles Whittlesey, 

 who, it would seem, had noted the distinction as early as 1866. 



