XX RECENT PROGRESS OF THE GLACIER THEORY. 



among the direct effects of plasticity.* I considered that my 

 theory was strengthened by being rendered so far independent 

 of an effect which I admitted with reluctance.f 



There remained, however, three classes of facts requiring 

 explanation, and which were evidently connected with one 

 another (1) there was the reconsolidation of a glacier more or 

 less extensively fissured by open cracks, which is yet seen ulti- 

 mately to recover its continuity ; (2) the reunion by pellucid 

 ice of the surfaces rent by the bruising action producing the 

 veined structure ; (3) the transformation of the neve into per- 

 fect ice. On the first point I had early come to the conclusion 

 that the greater fissures of ice were sealed up merely by the 

 collapse and reunion of the particles influenced by time and 

 pressure, and aided by the softening effects of the plentiful affu- 

 sion of water. Next I was disposed to account, at least in part, 

 for the reunion of the surfaces of internal sliding, or the forma- 

 tion of the veined structure when it arises or is modified in the 

 glacier proper, by a similar result of pressure and cohesion. I 

 do not think that any recognition of infiltration in connection 

 with this structure will be found in my writings subsequent to 

 1844. A third fact was, however, to be explained before the 

 congelation of water in the depths of the glacier could be dis- 

 pensed with ; and until that was effected, it was, to say the least, 

 superfluous to affirm that congelation had no effect in producing 

 the " blue veins." The difficulty now centered on the conversion 

 of the nve into glassy ice, a process (in my opinion) very inti- 

 mately connected with the original formation of the veined struc- 

 ture in the higher glacier, as the following passage, written in 

 Italy early in 1844 (therefore founded on my observations of at 

 least the previous year) , clearly shows : After explaining the 



* Travels, 1st Edit., p. 384 ; 2d Edit., p. 386. 

 f See the limitations mentioned in Travels, pp. 232, 360, 372 of both editions. 



