1876.] 59 ' [Wright. 



tliem from the melting ice sheet, after the analogy of snow from the 

 atmosphere, or silt from water. The seclusion of the air from the 

 mass below, prevented its oxidation, and preserved its original color, 

 while that precipitated from the ice, was long exposed to both air 

 and moisture, and hence would have the red color produced by 

 oxidation. As I have already proved, the belt of ridges just de- 

 scribed was a part of the precipitation spoken of, for it passes over 

 some of these hills. 



In conclusion, I must express my desire to have this whole class 

 of phenomena still more extensively and carefully studied. We 

 could theorize more confidently if we were sure we had been over 

 the whole ground. In working out the problem, we need to trace 

 with more certainty the pebbles to their local origin; we need to 

 know more about the relation of the series I have investigated to 

 what is farther north, and should also look for other series besides 

 those we have already found. We should also consider mathemat- 

 ically what effect the contour of the Merrimack Valley would have 

 in giving local direction to the portion of the ice sheet included in it 

 at the various stages of the glacial epoch. At the earlier and later 

 stages the influence of it would be larger than at the period of 

 greatest accumulation, even if, as Dana suggests, there would then 

 have been both an upper and an under current. We should consider 

 how much the direction of a moraine-bearing glacier would change 

 to the eastward, when the barriers of the water shed to the east of 

 Manchester were once passed. 



I desire also to express my gratitude for the advice, and other 

 service rendered me by the persons named in the body of this paper, 

 and to add the name of Mr. G. W. W. Dove, who has kindly pre- 

 pared the maps for me, and aided in various other substantial ways. 



Since the foregoing was in print, Mr. Clarence King has fur- 

 nished me the following account of his observations upon the retreat- 

 ing glaciers of the Rocky Mountains. His observations are so direct, 

 and the phenomena he describes are so similar to those connected 

 with the ridges I have been investigating, that I cannot doubt he 

 has hit upon the solution of the vexed and long mooted problem con- 

 cerning the formation of "kames." Indeed, it would seem that he 

 had, with his own eyes, seen them formed in such manner that the 

 hypothesis of surface currents introduced by Upham and Hitchcock 

 will hardly be necessary. 



