258 
INTERNAL STRUCTURE AND 
ers may think tediously, upon this part of my 
subject, because the stratification of tho glacier 
has been constantly questioned by the more re- 
cent investigators of glacial phenomena, and has 
indeed been set aside as an exploded theory. They 
consider the lines of stratification, the dirt-bands, 
and the seams of ice alternating with the more 
porous snow, as disconnected surface-phenomena, 
while I believe them all to be intimately con- 
nected together as primary essential features of 
the original mass. 
There is another feature of glacial structure, 
intimately connected, by similarity of position and 
aspect, with the stratification, which has greatly 
perplexed the students of glacial phenomena. I 
allude to the so-called blue bands, or bands of 
infiltration, also designated as veined structure, 
ribboned or laminated structure, marginal struc- 
ture, and longitudinal structure. The difficulty 
lies, I believe, in the fact that two very distinct 
structures, that of the stratification and the blue 
bands, are frequently blended together in certain 
parts of the glacier in such a manner as to seem 
identical, while elsewhere the one is prominent 
and the other subordinate, and vice versd. Ac- 
cording to their various opportunities of investi- 
gation, observers have either confounded the two, 
believing them to be the same, or some have over- 
