upon the ground that all traces of stratification are obliterated before the appearance of the veined structure. It is, however, now well known that the primitive structure has been detected after the appearance of the veins on the surfaces of glaciers—the veins, indeed, have been observed in the walls of crevasses cutting the original structure.[1] It is proved thereby that the original structure remains in existence down to a low point, and that, so far at least, it is not obliterated."[2]
It has also been urged that "the blue veins of glaciers are not always, nor even generally, such as we should expect to result from stratification. The latter would furnish us with distinct planes extending parallel to each other for considerable distances through the glacier; but this, though sometimes the case, is by no means the general character of the structure." With this observation I agree. It amounts, however, only to saying, that it is impossible to con-
- ↑ This of course proves that the origin of all the veins is not found in stratification, but it does not prove (as some appear to think) that all of the veins have a different origin.
- ↑ I believe that I have seen the planes of the original bedding still remaining parallel to the surface in some icebergs floating into Disco Bay, which had come from a glacier at least 20 miles long. If I am not mistaken, this is a most important and significant fact.
parallel to the length of the glacier" (p. 3.) "In some parts of the glacier it appears more developed than in others. . . It penetrates the thickness of the glacier to great depths. It is an integral part of its inmost structure" (p. 5.) "The breadth of these (bands) varies from a small fraction of an inch to several inches" (p. 8). "This structure consists in the alternation of more or less perfectly crystallised ice in parallel layers, often thinning out altogether like veins in marble" (p. 19).
Forbes' "veined structure" is frequently cut, both horizontally and vertically, by other veins, which latter seem to me to have clearly a different origin from the former. Proper discrimination has not hitherto been made between the two. Observers sometimes call one, sometimes the other, and sometimes both, the "veined structure." It would, I think, be convenient and appropriate to term Forbes' structure "the laminated structure of glacier." In 1867, upon the surface of a glacier in the Jakobshavn district, North Greenland, I saw three series of veins crossing each other in three different directions, forming a cross-bar or net-work pattern upon the ice. This was certainly not Forbes' structure.
