1876.] 57 [Wright. 



ice, where stratification of sand and gravel would take place. The 

 material above would slide down upon them, or be washed rapidly 

 down upon them in times of floods, which would account for the 

 existence of such large unstratified masses above, and mingled with, 

 stratified portions. Daring July and August the power of the sun's 

 rays, united to the summer showers, would set free vast bodies of 

 water which would, in part, escape along channels upon the surface 

 of the glacier, and would pour forth a mighty volume from its foot. 

 This would aid in moving the pebbles, and in transporting the mate- 

 rial, and in modifying it when it was finally left by the retreating 

 glacier to rest immediately upon the till, or ground moraine. In 

 places, these currents of water might well remove it altogether, and 

 it would be sufficient to fill the basins south of the glacier and upon 

 temporary lakes, where stratified material would accumulate from 

 the unstratified kame, and merge it in a plain; as, for example, at 

 Ballard Vale ; where the natural drainage is north. When, however, 

 that was dammed up by the retreating ice wall, there would have 

 been for some time, a broad, shallow lake, whose surface was even 

 with the southern drainage level and whose bottom now constitutes 

 the plain shown in Plate II. 



Of the influence of these surface currents, Prof. Jamieson 1 has 

 speculated, though with some degree of vagueness. He speaks of 

 surface currents upon the glacier sweeping the sand and gravel into 

 " lines along the margin." His idea, however, seems to be that it is 

 the terminal margin, and that the kames are of the nature of termi- 

 nal moraines, running across the valleys in the arc of a circle at right 

 angles to their axes. Mr. James Geikie, however, in his second edi- 

 tion, 2 contends that the kames of Scotland run in a direction parallel 

 with the general course of the valleys. This conforms to what is un- 

 questionably the fact in the portions of New England which we have 

 described. Mr. Geikie now speaks in more unqualified terms than in 

 his first edition of the frequent unstratified character of the forma- 

 tion, 3 and accepts Mr. Jamieson's conclusions that the sea could not 

 have had anything to do with their formation, since the angle of the 

 inclination of the sides is much sharper than could be formed under 

 water. He now attempts to account for them as the result of " sub- 

 glacial rivers." 4 But among other things, the long extent of the 



1 See Quart. Journ. Geol. Society for 1874, p. 329. 



2 The Great Ice Age. 2d ed. London. Daldy, Isbister & Co. 1877. See p. 242. 

 » Ibid, p. 240. 



« Ibid, pp. 239, 243, 469, 478. 



