86 ‘Prof. Forbes on a Remarkable Structure observed 
fully three hours’ good walking on the ice or moraine from 
the lower extremity of the glacier to the huge block of stone, 
under whose friendly shelter we were to encamp; and in the 
course of this walk (a distance of eight or nine miles, on a mo- 
derate computation, allowing for the roughness of the way) on 
the first day I noticed, in some parts of the ice, an appearance 
which I cannot more accurately describe, than by calling it a 
ribboned structure, formed by thin and delicate blue and bluish- 
white bands or strata, which appeared to traverse the ice ina 
vertical direction, or rather which, by their apposition, formed 
.the entire mass of the ice. The direction of these bands was 
parallel to the length of the glacier, and, of course, being ver- 
tical, they cropped out at the surface, and wherever that sur- 
face was intersected and smoothed by superficial water-courses, 
their structure appeared with the beauty and sharpness of a 
delicately-veined chalcedony. I was surprised, on remarking 
it to Mr Agassiz as a thing which must be familiar to him, to 
find that he had not distinctly noticed it before, at least if he 
had, that he had considered it as a superficial phenomenon, 
wholly unconnected with the general structure of the ice. But 
we had not completed our walk before my suspicion that it 
was a permanent and deeply-seated structure was fully con- 
firmed. Not only did we trace it down the walls of the cre- 
vasses by which the glacier is intersected, as far as we could 
distinctly see, but, coming to a great excavation in the ice, 
at least 20 feet deep, formed by running water, we found the 
vertical strata or bands perfectly well defined throughout the 
whole mass of ice to that depth. An attempt has been made 
to convey some idea of their appearance in Plate I. Where 
the plane of vertical section was eroded by the action of water, 
the harder seams of blue ice stood protuberant ; whilst the in- 
termediate ones, partaking of a whitish-green colour and gra- 
nular structure, were washed out. We did not sleep that 
night until we had traced the structure in all directions, even 
far above the position of our cabin, and quite from side to side 
across the spacious glacier of the Finster Aar. 
During the whole of our subsequent residence amongst the 
glaciers, the phenomena and causes of this structure occupied 
our thoughts very frequently. We had much difficulty in ar- 
riving at a correct description of the manner of its occurrence, 
