Alps alone, the basins of the Gorner and the Fee Glaciers present a certain resemblance to that which we have described; those of the Argentière and the Northern Miage are yet more like it; while the Mer de Glace, among the aiguilles of Mont Blanc, is the nearest rival of this "Place de la Concorde of Nature," as it has been not inappropriately termed. One of the most striking prospects of this courtyard of the ice-king's palace is obtained from the Concordia hut, a rude chalet at the base of a rocky spur, in which the night is passed before making the ascent of the Jungfrau and sundry other peaks. From beneath this spot for a considerable distance the wide field of névé1 shelves so gently as to seem nearly a plain, and its surface is almost unbroken. It is only as the slope steepens, on approaching the base of the actual peaks or the foot of the curtain walls, that crevasses become frequent. Then the frozen snow, for here it can hardly be called ice, is riven into strange forms, and usually one chasm-named the Bergschrund— wider and more persistent than the rest, severs the snow and ice of the glacier basin from the snow and ice of the actual peaks. Above this rift the solidified water is motionless, for it is fast frozen to the rocks; below it the whole mass creeps slowly downwards towards the valley of the Rhone. The snow which

1 The name applied to the material of the upper part of a glacier, where it is more nearly in the condition of frozen snow. The German term is firn.

falls on the steep slopes of the peaks soon shoots down in avalanches to augment the accumulation below, and a thick layer gathers annually all over the wide expanse of the basin, for at this elevation. rain is not common. So the glacier is born, so it is nourished. I have described its birthplace, I have dwelt on its beginning in some little detail, because in the pages which follow it will be necessary more than once to call up before our minds a similar scene.

The ice, as has been said, is at first comparatively smooth and free from débris. Here and there, however, a solitary boulder forms a black spot on its pure surface, or a small scatter of them trails forth from the foot of some rocky spur which is more prominent and precipitous than its fellows. These boulders after a time become more frequent, till at last they begin to form a kind of selvage on the edge of the icestream. Obviously, as the valley which it descends becomes better defined and sinks deeper into the mountain mass, the crags and precipitous slopes on either hand rise higher and barer, and stones more often come thundering down from them or are swept along by avalanches of snow. Now and again a block,

more headlong than the rest, closes its career by one vast leap which lands it out on the glacier some hundreds of feet away from the rocks; but the majority fall on or near the edge, so that on this a mound of boulders, large and small, together with grit and earth, gradually accumulates and is slowly

swept along as the icy mass crawls downwards.1 This mound is called a moraine. By the confluence of separate glens two glaciers are joined into one. If moraines have already formed at their sides, those at adjacent edges are combined.2 The solitary blocks also travel on with the ice. If they are flat in form, they become elevated on pedestals; for they act as parasols, and so the ice beneath them melts less rapidly than the exposed surface of the glacier. Sometimes they travel to the end of the ice-stream; but if small, they are more often engulfed in a crevasse, where we leave them for the present.

When the bed of a valley has a fairly uniform slope, the glacier descends in a comparatively unbroken flow, till it melts away under the increasing temperature and is transformed into a river. In this case the medial moraines are also continuous, and produce great mounds, almost comparable with railway embankments. It must not, however, be supposed that these consist entirely of débris. The ice beneath them, as in the case of the glacier-table, is protected from the rays of the sun, and forms at last an inner ridge or core, on which sometimes the outer cover lies in very unstable equilibrium. The Unter Aar Glacier, on which the general gradient is only about

The Alpine glaciers advance on an average about a foot a day. Large glaciers move more quickly than small; from 20 to 40, and in one case 50 feet has been recorded for the great ice-streams of Greenland. See Prestwich, "Geology," Part II. chap. xxxiii.

2 This is called a medial moraine, the others being called lateral.

In them much

6 in 100, affords a good example of these unbroken moraines. Commonly, however, the bed of the valley is more step-like, one or two steeper descents interrupting the uniformity of its slope. As the glacier passes over these, it is rent into a wilderness of icy crags sundered by yawning crevasses. of the moraine is engulfed; part of the débris descends. to the bottom of the glacier, part is arrested in the narrower fissures and becomes embedded in its mass. At the base of the icy cascade the chasms often close up again, and the glacier moves on as a comparatively smooth stream. But the moraine has now lost its banklike form, its materials have been scattered. Some of the blocks which were swallowed up in the shallower fissures appear again, in some cases disclosed by the melting of the ice, in others possibly 1 extruded by an upward motion in the mass itself. Thus, as a rule, the moraine, before reaching the end of the glacier, has become spread out over the surface. Sometimes for a considerable distance the mass of scattered débris - grit, gravel, and boulders of all sizes almost conceals the lower part of the icestream. The load at last is dropped at the end of the glacier, where it forms a bank called the terminal moraine. This bank is usually more or less a crescent in plan, the convexity pointing downward, in correspondence with the shape of the ice-stream; and if

1 The possibility of this supposition will be discussed in a later chapter.

its end remain for long at the same spot, the moraine attains considerable dimensions. If, however, the glacier be slowly shrinking, the mound is replaced by a wide scatter of boulders and débris. The same is true of the lateral moraines. These also occasionally form large banks, resting partly on the slope of the valley, partly on the edge of the ice. Sometimes they too may be, as it were, stranded, and become features no less definite than the terminal moraine; sometimes their materials also may be scattered, owing to a steady shrinkage of the glacier on the sloping sides of the valley. The volume of the moraine is dependent on a variety of circumstances, but the nature of the rocks in the adjacent crags and the arrangement of their divisional surfaces are always important factors. For instance, the amount of moraine stuff on the glaciers descending the western valleys of the New Zealand Alps around Aorangi is comparatively small, while on those of the eastern side it is very large, covering the icestreams for about a quarter of their whole length, and piled up in heaps or hillocks more than fifty feet high. The cause is this: the mountain range is largely composed of slabby slaty masses of stratified rock, which dip towards the west. On that side the valleys descend nearly along the slope of the beds; the cliffs are low, and débris does not roll far; while on the eastern face the rock structure lends itself to the formation of great precipices, from which masses