Neuchâtel, many erratics are scattered among the pine-trees. The largest, the famous Pierre à bot, contains from 40,000 to 45,000 cubic feet, and is perched at a height of 820 feet above the Lake of Neuchâtel. It, like most of its neighbours, is protogine from the Mont Blanc range.

The Alpine and sub-Alpine region will repay us for further study, because there is no reason to suppose that any portion of it has been submerged beneath the sea, either at any time during the Glacial Epoch, or since this came to an end. Hence we may safely assume all the glacial deposits to be results of the action of land-ice, and regard them as types for comparison with those in other countries of which the origin is less certain. Accordingly we will retrace our steps to the ends of the glaciers, in order to ascertain what difference, if any, exists between the morainic material which is still in process of accumulation, and that which has been distributed over the lowlands. In the recent moraines blocks of various sizes, from a few inches to many cubic yards in volume, are confusedly piled together; the latter, however, are comparatively rare, though occasionally a monster, like those already mentioned, may be found; as, for instance, the great block of impure serpentine lying some distance from the end of the Schwarzberg glacier on the little plain near the Mattmark Hotel, which measures about 50 feet each way. A quantity of mud, sand, and small stones is

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mingled with the coarser materials in the moraines. In those at the foot of the Fee Glacier, the fine material appears generally to be at least equal in volume to, and sometimes rather more than, the larger blocks; in other cases it is not quite so much. We are not, however, obliged to suppose that all this mud has been extruded from beneath the glacier, for it is as abundant in the upper as in the lower part of the moraine, and the sloping surface of the ice is coated for a considerable distance up with mud and sand, so as to be a dull grey in colour. known that fine mud, grit, and small stones are common on the surface of glaciers. This material is swept down from the barer cliffs of the mountains by snow avalanches or streams, or is formed during the fall of rocks as they impinge on the crags, to their mutual destruction. A cloud of dust accompanies the volley of descending fragments; for smokeless powder is not used in Nature's artillery. The comparative rarity of ice-worn and striated stones. in the recent moraines is a further proof that they owe little to subglacial débris. The torrent, however, which issues from beneath the glacier and carries off the water-whether melted from its surface or contributed by streams which have made their way under the ice-is turbid with mud, much of which has been derived from the subjacent rocks. The amount varies with the time of the year, because the stream is small and clear, comparatively speaking,

in the winter months, for its volume largely depends upon the rate at which the ice is melting. Dolfuss calculated that the Aar in the summer time trans

ported at its issue from the glacier 142 grammes of sediment per cubic metre, or 7040 of the weight of the water, but that the amount for the whole year was only 2000. Observations on seven Greenland and ten Norwegian glaciers gave as the mean results for the summer months 147.9 grammes per cubic metre; and Professor Helland calculates that all the glaciers of Justedal during the month of July transport 2,000,000 kilogrammes, and during the entire year 180,000,000 kilogrammes, which is equal to a mass of rock 41 metres cube. As the area of these glaciers is about 900 square kilometres, this mass is equivalent to the removal annually of a layer about .0766 millimetres thick (or .003 inch) from the entire surface beneath the ice.1 But not even the whole of this, as already said, is really worn away from the glacier bed; for a not inconsiderable part either comes from the stones which help in the work, or has been washed by glacier streams from the surface of the ice, or has been swept beneath it as débris by lateral torrents. Professor Heim, as the result of his careful observations, considers glaciers, as a rule, to be much less important agents of denudation than mountain torrents, for one

1 See summary of Heim's Handbuch der Gletscherkunde, by F. F. Tuckett. Alpine Journal, xii. p. 301.

of these, though its collecting basin is only one-tenth of the area of the Unter Aar Glacier, has been known to bring down, when swollen with rain, from 10,000 to 100,000 cubic metres of débris in the course of a day or two. Its ordinary daily yield is no doubt less than that of the glacier, but the occasions of energetic action are so frequent as to make the work of the one much more important than that of the other. Certainly the Alpine glacier at the present day transports but little ground moraine. Observers have succeeded in making their way for short distances beneath the ice, and have found between it and the rock nothing more than a mere film of mud, with an occasional boulder, generally small and solitary.

The mode in which a glacier terminates varies with local circumstances. Here it may end in a ravine, there descend on to comparatively level ground; here the final ice slope may be steep, there it may shelve down gently; here it may be completely masked by débris, and the white water spouts and foams from among the grey boulders as if from hidden springs; there, as is more usual, the torrent rushes out into the daylight from beneath an arched cavern of ice which vies in colour with the turquoise. Sometimes a bare and smoothed slope of rock must be climbed to reach the ice, but in the case of the larger glaciers a comparatively level space generally lies at its foot, the breadth of course being dependent

on that of the valley which it occupies. This is strewn with boulders and stones, some subangular, occasionally even rounded, some angular and uneven. The former have been brought by the torrent, or at any rate have performed much of their journey, beneath the ice; the latter have travelled for the

whole way upon it. Similar narrow plains may often be observed in the upper parts of valleys, the heads of which are occupied by glaciers, as, for example, between Saas-im-grund and the Mattmark Hotel; but as the torrent is constantly adding débris to these deposits, especially in time of flood, it soon becomes difficult, except in the case of the largest erratics, to ascertain how much may be regarded as a direct, and how much as an indirect, result of the glacier,

Sometimes, however, these erratics furnish us with testimony which has a not unimportant bearing on the question of the effect of ice. The glaciers of the Alps, even at the present day, are liable to oscillations,1 which occasionally are far from unimportant. About forty years since they began a general retreat, which, however, appears now to have ceased. In some cases a length of more than a thousand yards of rock or débris has been exposed, which previously had been concealed beneath the ice, and the thickness of the glacier has been diminished in places from 150 to more than 300 feet. Where the ice has rested on

1 To these a fuller reference will be made in a later chapter.