the faces, and the weathered ice beneath, and you will expose sections of the mingled strata of pure and of imperfect ice, and see clearly enough that the primitive structure of the glacier has not been effaced, although it has been obscured.
Notwithstanding all that has been written to the contrary by very eminent authorities, I believe that the strata of ice which are formed by weathering, upon the beds of snow that are deposited in the higher regions, exist (unless they are originally of very small thickness) to the ends of the glaciers, and that many of the veins of blue ice which are seen on the surfaces of the lower parts of Alpine glaciers are nothing more than the outcropping of the primarily horizontal strata.
Some of those who have maintained the contrary opinion, have evidently had a very insufficient idea of the extent to which the upper snows are pervaded by the strata of blue ice, and of their thickness. In the Appendix it is shown that there were in the upper 22 feet of snow at the summit of the Col de Valpelline, in 1866, no less than 75 layers of ice, one of which was more than 6 inches in thickness, whilst numerous others ranged from half-an-inch to one inch. The total depth of these 75 layers amounted to 25⅝ inches, or nearly one-tenth of the mass which we were able to penetrate. As far as I am aware, it has not been proved experimentally that it is possible (by compression, or in any other way) to obliterate a plate of ice, even an inch in thickness, placed between snow, or between ice of inferior density, except by liquefaction of the entire mass.
Others who have pronounced against the possibility of the horizontal strata of blue ice contributing any of the veins of blue ice which constitute the veined structure[1] of glaciers, have done so
- ↑ The late Principal J. D. Forbes was the first to attach any importance to the veined structure of glaciers. I gather the following definitions of it from different pages of his Occasional Papers. "I cannot more accurately describe it, than by calling it a ribboned structure, formed by thin and delicate blue and bluish-white bands or strata, which appear to traverse the ice in a vertical direction, or rather which, by their apposition, formed the entire mass of the ice. The direction of these bands was
