214 On tfu tfurfaa Geology of tfo Basin of the 



phenomena" <>t' this region have brought to light are briefly 

 as follows : 



1st In the northern half of this area, down to the paral- 

 lels of 38 — J" . we find, not every where, but in moBt localities 

 where the nature of the underlying rocks is such as to retain 

 inscriptions made upon them, the upper surface of these rocks 

 planed, furrowed or excavated in a peculiar and striking man- 

 ner, evidently by the action of one great denuding agent. No 

 one who has seen glaciers and noticed the effeel they produce 

 on the rocks over which they move, upon examining good 

 exposures of the markings to which I have referred, will fail 

 to pronounce them the tracks of glaciers.* 



Though having a general north-south direction, locally the 

 glacial furrows have very different bearings, conforming in a 

 rude way to the present topography, and following the direc- 

 tions of the great lines of drainage. 



On certain uplands, like those of the Wisconsin lead region, 

 no glacial furrow.- have been observed (Whitney), hut on 

 ni"-i of the highlands, and in all the lowlands and great val- 

 leys, they are distinctly discernible if tin- underlying rock has 

 retained them. 



2d. Some of the valleys and channels which hear the 

 mark- <>f glacial action— evidently formed or moditied bv ice, 

 ami dating from the ice period or an earlier epoch — are exca- 

 vated far below the present lakes ami water-courses which 

 occupy them. 



These valleys form a connected system of drainage, at a 

 lower level than the present river By stem, and lower than could 



he produced without a eolit ilieiital ele\atioii of several liun- 



imiii my own iii.-crv.it i n tin' sotion of glaciers I'll rook surfaoon in 



Upi nod in Oregon and Washington Territory, 1 <io not hesitate t<> assert that 



i '' have produced such effects, A different view is takon of 



thin Bubji ct, it i- inn-, I nit only by those who either have never Been a glacier or 



never Been tin- markings in qui il , The track of a glacier is as unmistaka- 



a of n man or a bear. 



