I 26 GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



The melting begins at certain points between the crystalline plates and spreads 

 in a direction parallel to them, instead of across, or through them. The planes 

 of these melting figures are parallel to Forel's stripes, and either feature when seen 

 may be used for orienting the crystal. In addition to the stripes of Forel, there 

 is to be seen a very conspicuous system of parallel ridges and furrows, covering 

 the outside of softened granules, which can have no connection whatever with the 

 crystalline structure. The ridges are either continuous, or consist of a series of 

 regularly placed points, forming a wavy, irregular pattern about the crystal. 

 The appearance suggests that seen upon the inside of one's finger-tips and thumb. 

 It shows itself when the adjacent faces of the granules begin to separate and is 

 due to differential melting at the siirface, but it is far from clear what could give 

 rise to such a regularly irregular pattern. 



By means of the polariscope it was found that there is a tendency towards the 

 orientation of the granules about the nose of the Victoria, Yoho, and Illecillewaet 

 glaciers, the other two not being tested. The Victoria shows distinct stratifica- 

 tion about the oblique front, the Yoho indistinct, and in the case of the Illecille- 

 waet, the stratification about the nose seems to have been completely destroyed. 

 Vertical sections of the ice were prepared, cut crosswise and lengthwise, and these 

 were compared with horizontal sections and oblique sections. It was found that 

 there is a marked tendency to arrange the optic axes of the granules in the basal 

 layers near the nose in a vertical position, from one-fourth to one-third of them 

 being estimated to be so oriented. The cause of this orientation is not yet 

 apparent, but connected, undoubtedly, with the method of growth of the granules 

 themselves. In order to account for the orientation which he found in the 

 Greenland glaciers, Drygalski assumed that the granules were separately melted 

 and refrozen with their axes parallel with the direction of pressure, which he 

 considers at right angles to the strata. If it is true that the direction of pressure 

 determines the position that the crystalline plates will assume, and hence the 

 position of the optic axes, which the writer seriously questions, then the space 

 occupied by a single crystal, which has been completely melted, should contain 

 a large number of radially arranged prisms, each standing at approximately right 

 angles to the portion of the ice surface to which its base is attached. Owing 

 to the law of transmission of forces by a liquid the pressure is equal in all directions 

 whether this pressure arises from the weight of the superincumbent ice, or because 

 of the expansion of the water in the closed cavity just before freezing. Drygalski 

 is in error in supposing that the pressure experienced by the liquified granule is 

 vertical only, since, if confined, the water would press outward in all directions. 

 In case the position of the refrigerating surface, or surfaces, is the cause of the 

 orientation of the plates, then in the closed cavity occupied by the liquid granule, 

 there should be formed a mass of radially arranged prisms, similar to those 

 observed by the writer upon the Lefroy and by Agassiz upon the Aar. In 

 either case, the cavity should be filled with small radially arranged prisms and 

 not by a single crystal with its axis in a vertical position. This furnishes rather 

 conclusive evidence that granules and blue bands never have existed in a com- 



