1841.] COURSE OF THE VEINED STRUCTURE. 5 



study, this pervading slaty or ribboned structure, to be found 

 probably in one part or other of every true glacier. 



With regard to extent, this structure was observable on the 

 Lower Glacier of the Aar, from its lower extremity up to the 

 region of the firn or neve, where, the icy structure ceasing to 

 exist, it could not be looked for ; yet even there, where fre- 

 quent thaws, induced by the neighbourhood of rocks or stones, 

 produced a compacter structure, the veins became apparent. 

 In some parts of the glacier, it appears more developed than 

 in others ; in the neighbourhood of the moraines, and the wall's 

 of the glacier, it was most apparent. This would seem to infer 

 a relation to the frequency of thaws and recongelation. 



It penetrates the thickness of the glacier to great depths. 

 It is an integral part of its inmost structure. That it could 

 not be the production of a single season I was speedily con- 

 vinced, by observing that where old crevasses fissured the gla- 

 cier transversely, the veined structure not only was reproduced 

 on either side, but frequently with a shift or dislocation, or 

 series of parallel fissures, presenting sometimes a series of dis- 

 locations advancing in one direction. 



The course of the veined structure was, generally speaking, 

 on the Glacier of the Aar, strictly parallel with its length, and 

 that with a degree of accuracy which seems extraordinary, if 

 we attribute its production to the remote influence of the 

 retaining walls of the glacier, distant at least half a mile. Near 

 the inferior extremity, where the declivity becomes rapid, the 

 structure varies its position in a manner very difficult to trace 

 satisfactorily. There can be little doubt, however, that the 

 nearly horizontal bands which appear on the steep declivity of 

 the glacier at its lower termination, are nothing else than the 

 outcropping of these bands, which have there totally changed 

 their direction, being transverse instead of longitudinal, and 

 leaning forwards in the direction in which the glacier moves 

 at a very considerable angle. The ice in this part of the glacier 

 is distinctly granular, being composed of large fissured morsels, 

 nicely wedged together ; and the ribboned structure is greatly 



