2\>x 



action, and D P would evidence abrasive action almost as 

 pronounced as the stoss seite. 



To return to figure 10, BO does not mark the preglacial 

 profile of the roche moutonnee ; most probably the original 

 profile was somewhat as the dotted line O O' O" in the figure 

 the face B C evidencing a long recession as from O" to 0. 

 Nor is this purely deductive, it is based partly on observa- 

 tion, and partly on mechanical principles suggested by 

 analogies taken both from comparative stream studies and 

 from the ordinary operation of mechanical laws. Fig. 13 

 is a good example of the roches moutonnees found in the 

 San Joaquin Valley. 



I I) represent a dec 

 so constricted at tl 

 m along the portic 



