198 THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN 



and the configuration of the eroded surface is the test of the domi- 

 nance of the one or the other type. It is obvious that the least 

 eroded part of the eminence must come to stand forth and the 



Fig. 2. — Diagram to illustrate the effect of erosion upon a hill, on the assumption 

 that the capping of ice, SC, is protective. The dotted line represents the original 

 outline of the hill; the solid line, the contour resulting from erosion. 



most eroded part must retire toward the center. If the snow- 

 covered flank or brow is indeed a protected area, it must gradually 

 come to stand forth from the retiring wear-and-weather contours 



Fig. 3. — The same hill as in Fig. 2, eroded according to the hypothesis that ice 

 is a superior eroding agent. SC represents the original snow bank which comes to 

 occupy a basin as erosion goes on. 



adjacent, as a rather definite embossment, as illustrated in Fig. 

 2. As time goes on, the summit of the hill should migrate toward 

 this protected area and it should tend to become the summit, 

 while the snow-cap in turn migrates into its lee. A marked asym- 

 metry should gradually develop. 



On the other hand, if the snow mass, accumulating from year 



