128 GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



are subjected to more or less of a rotary movement and' a sliding along their 

 limiting surfaces, by which the internal stresses of the glacier are undergoing 

 constant readjustment and the ice mass permitted to move under the in- 

 fluence of gravity. These views of granular growth would call for constant 

 changes in the form, size, and number of the granules and in their relative 

 position. 



If the principles underlying these views — melting under pressure or friction — 

 were alone operative in granular growth there should occur a much larger number 

 of smaller granules mingled with the larger in the basal layers about the nose of 

 a glacier. Owing to the manner in which the granules are keyed together the strain 

 upon the smaller would be relieved as they diminished in size and would be 

 transfen'ed to the faces of the larger neighbors. Lying in between the coarser 

 granules we should expect a considerable number of these smaller remnants, 

 but such occur only somewhat sparingly. The remarkably well preserved 

 blue bands in the basal layers about the nose of the glacier furnish conclusive 

 evidence it seems to the writer that the granules have not been destroyed since 

 the bands were produced and that they have not materially shifted their position 

 with reference to their neighbors. Upon the surface of the lower Asulkan 

 Glacier these bands were found so thin that thirty were included within the dis- 

 tance of four inches, several necessarily cutting across adjacent granules. Any 

 perceptible shifting of the granules as the result of sliding or rotation would give 

 rise to faulting of these bands, while their destruction by either slow or rapid 

 melting would cause abrupt gaps in the continuity of these bands. The preser- 

 vation of the depositional laminje from the neve to the nose would seem impossible 

 if the granules are being destroyed and reformed or rotated out of their original 

 position with respect to their neighbors. 



Third. — The "dry union" of granules described on page 40 of this report 

 accounts for the reduction in the number and an increase in their size toward 

 the nose of the glacier. According to this theory the molecules of the yielding 

 granule give up theii- own crystalline arrangement and without any apparent 

 melting are immediately incorporated into the body of the controlling granule. 

 Heim's view was that such a union could occur onh' when the main axes of the two 

 grantiles were placed in approximately parallel positions,' but the experiments 

 of Hagenbach-Bischoff showed that such union could occur regardless of the posi- 

 tion of the axes, 2 and this he regarded as the true cause of granular growth 

 in the glacier. This view was accepted by Emden in his prize essay, " Ueber das 

 Gletscherkorn," published in 1890. It furnishes the simplest theory of granular 

 growth, not of glacial motion; accounts for whatever uniformity exists in the 

 size of the granules, calls for no shifting of the granule relative to its neighbors, 

 and hence permits the continuity of laminas and blue bands. 



'Handbuch der Gleischerkunde, 1885, s. 330. 



^Verhandlungen der N aturjorschenden Gesellschaft in Basel. Bd. vii, 1888, s. iga; Bd. viii., i88g, s. 635 

 und S21. .Archives des Sciences physiques ei naturelles, T. x.xiii., 1890, p. 373. 



