208 T. C. CHAMBERLIN — GLACIAL STUDIES IN GREENLAND. 



the first layer is compelled by the general friction to move somewhat for- 

 ward, and in time to join the common moving mass, carrying the over- 

 thrust layer of debris between it and the ice-layer above. The way is 

 then opened for a repetition of the process. This picture of the behavior 

 of the ice is quite radically different from that entertained by the viscous 

 hypothesis, in which the ice is supposed to flow down the lee side of a 

 prominence, as if it were liquid. The motive power here seems not so 

 much gravitation pulling a fluent body forward as the thrust of a rigid 

 body by a force in the rear. 



Behavior of the Ice in passing over low Prominences. — Several excellent 

 opportunities for observing the behavior of ice in passing over low em- 

 bossments were offered. From the front of the embossment there origi- 

 nated laminse which extended backward with a graceful, arching curve, 

 much like the profile of a drumlin. A portion of the ice remained be- 

 tween these curving laminations and the upper and rear portion of the 

 embossment. After reaching a point in the rear of the embossment, the 

 laminae curved downward with increasing rapidity until well in the lee, 

 when they turned about at a more or less sharp curve, or even angle, and 

 ran backward to some point not far in the rear of the embossment, where 

 they ended. The higher laminse made the longest curves and had the 

 sharpest angles in the lee of the embossment. It appears obvious that 

 the ice in the lee of the embossment moved more slowly than that above ; 

 hence the doubling of the laminae upon themselves. It appeared upon 

 close inspection that some of the inthrust layers described above consist 

 in reality of very sharply reduplicated laminae. It seems, therefore, 

 that this phenomenon grades insensibly into the preceding. A study of 

 laminae not associated with embossments showed many signs of doub- 

 ling upon themselves in a similar way. It appears, then, that there 

 is a- gradation from laminae that simply suffered doubling up to layers 

 that obviously sheared upon each other and produced manifest uncon- 

 formity by pronounced overthrust. (Figures 11 and 12, plate 8; also 

 figure 9, plate 7.) 



Development of blue Bands. — Some of the laminae observed to originate 

 on the brow of embossments of rock were simply blue bands. They were 

 even seen on bowlders underlying the ice. So far as observed, the blue 

 bands started at some little projection or rugosity in the brow of the 

 embossment. From this point they extended rearward, usually curving 

 a little upward and free frorn the embossment, following a drumloidal 

 curve until they had passed its lee, when they turned downw^ard and 

 sometimes returned as described above. Now, it is interesting to note 

 that within the curved loop in the lee of the embossment I observed in 

 one instance several nearly vertical blue bands, standing parallel to each 



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