42 GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



was noted by Drygalski in the granules of the Greenland glaciers and described 

 briefly upon page 488 of his report cited. It had been previously observed 

 and described by Emden in his paper Uber das Gletscherkorn, p. 22, figure 

 5, and designated as melting water curves. While neighboring granules were 

 in position, no correspondence could be made out between the ridges and 

 furrows of adjoining faces. An attempt was made to take impressions of the 

 markings but no suitable material was at hand. The wall preparation "alabas- 

 tine" reproduced perfectly the finger markings, but refused to work with a wet 

 ice surface. The "stripes of Forel" are delicate ridges, passing around the 

 granules at right angles to the main optic axis, and evidently connected with 

 the intimate crystalline structure of the crystal. They mark the edges of the 

 very fine plates of which each ice crystal is composed, placed together with their 

 flat faces perpendicular to the main optic axis. The ridges here described are 

 entirely different and do not suggest to the writer any possible explanation. 

 They are certainly due to the manner of surface melting but it is far from appar- 

 ent what could give rise to such a pattern. In the prisms of lake ice Emden 

 found both the melting curves and Forel's striping present, with an intermediate 

 type of ribbing, and concluded that all three were due to one and the same cause 

 and independent of the structure of the crystal (p. 24). 



Granules that have been well acted upon by the sun show a system of very 

 flat, circular disks, all with their planes parallel and at right angles to the main 

 optic axis. These were first observed and figured by Agassiz in his Systeme 

 Glaciaire, 1847 (plate vi, figures 7 and 10) and described also in his Geological 

 Sketches, vol. i, p. 275. They were believed by him to be air bubbles, flattened 

 by pressure, although observed to lie differently in adjoining granules. These 

 are now known as "Tyndall's melting figures," described in his Glaciers of the 

 Alps, Ed. 1896, pp. 353 to 361. They represent "vacuous space," left in the 

 ice by the contraction of the water when changed from its solid to its liquid 

 condition, the melting planes coinciding with the crystalline plates, of which 

 the granule appears to be composed. They are thus serviceable in enabling one 

 to determine the direction of the main axis of each granule, but there were not 

 enough of them seen at one time about the nose of the glaciers to settle the 

 question of the orientation of the granules. 



/. Blue bands. Many observations were made upon the blue bands, of 

 which the strata are generally composed, with the hope of shedding some light 

 upon their position and direction in the ice and their relations to the strata. In 

 general, they were found well developed about the nose and along the sides of 

 the glaciers, well up toward the ne"ve" region. The lower Victoria has too much 

 debris covering to enable them to be well seen at the surface, but in the tunnels 

 and moulins and along the walls of the surface streams they are to be seen in a 

 good state of development. At the mouth of the tunnel they were found to 

 average 0.59 inch to 0.75 inch and to dip back in to the glacier at an average angle 

 of 9, while the average slope of the strata was 26. This unconformity of the 

 laminae and strata is well shown in plate xn, figure 3, although the laminae 



