242 Canon Moseley on the " Veined Structure " 



The surfaces of the laminae of transparent ice, of which the 

 transverse sections are seen, as veins, on the sides of the crevasses, 

 are of a curved form, rudely resembling the hollow of the bowl 

 of a spoon* cut across at its widest part, whose edge is to be sup- 

 posed in contact with the surface of the glacier. If the lip be 

 supposed to be more and more compressed in front, it will show 

 the conoidal forms which the curved surfaces of transparent ice 

 affect higher and higher up the glacier ; and if it be sharpened 

 and elongated, it will show those towards which these curved 

 surfaces tend lower and lower down. Their forms have been well 

 represented by the late Principal James Forbes in a woodcut at 

 page 247 of his ' Occasional Papers on the Theory of Glaciers/ 

 which, by permission of his publishers f, I have copied (Plate III. 

 fig. 6). The outcrop of these conoidal laminae is most clearly 

 seen in respect to those of them which are marked and distin- 

 guished from the rest by sand or dirt entangled in their edges, 

 the softer white ice between which has been melted away. 

 These are the (so-called) dirt-bands, first observed by the late 

 Principal Forbes J. They display (though in a manner requi- 

 ring some attention to discover) the exact course of the veined 

 structure where it intersects the surface of the glacier. Fig. I 

 represents these dirt-bands as they appear on the Glacier du 

 Geant. It is copied (by his permission) from one given by 

 Professor Tyndall in his paper "On the Veined Structure of 

 Glaciers," in the Philosophical Transactions for 1859 (part i. 

 p. 305). 



At the terminal face or end of a glacier the frontal inclination 

 or inward dip of the spoon-like end of the surface of the blue 

 transparent ice is very small — at first only perhaps 5°, but rising 

 to 10°, 20°, up to 60° or 70°, if we follow the medial line of the 

 glacier, or axis parallel to its length. The veined structure is 

 most energetically developed at the sides of the glacier ; in the 

 central portions it is comparatively feeble. "It is not to be 

 regarded as a partial phenomenon, or as affecting the constitu- 

 tion of glaciers to a small extent only. Vast masses of some 

 glaciers are thus affected : by far the greater part of the Mer de 

 Glace, and its tributaries, is composed of this laminated ice"§. 

 "I have satisfactorily made out," says Forbes ||, "in every gla- 

 cier which I have had the means of examining with that view, 

 that the conoidal structure, however obscured, exists in all parts 



* Occasional Papers on the Theory of Glaciers, by Principal James 

 Forbes, F.R.S., p. 247- Edinburgh : Black, 1859. 

 t Messrs. J. and A. Black. Edinburgh, 1859. 

 X Forbes's ' Occasional Papers,' p. 246'. 

 § Tyndall, Phil. Trans. 1859, part i. p. 280. 

 || Occasional Papers, p. 20. 



