The accumulation of the débris hurled headlong by the mountains forms on the glacier-surface long lines of stone and earth, which are called _moraines_; these diverge in certain directions, according to the circumstances we now come to explain. The landslips which occur on the banks or edges of the glacier give rise to the _lateral moraines_, which are enlarged and extended daily by the twofold effect of the fall of stones and débris, and the progressive movement which carries them along with the whole mass of ice. Towards the centre of the great glaciers, in almost every case, is found a _medial moraine_; the result of the encounter of the lateral moraines of two glaciers which have united into one. These superficial moraines participating in the movement of the glacier, each of their blocks eventually rolls to the foot of the terminal precipice, and thus a _frontal moraine_ is formed on the very soil of the valley, like an embankment raised to prohibit the further advance of the ice. And, lastly, the bed of sand, gravel, pebbles, and detritus which is found beneath the glacier, and over which it glides, is called the _profound moraine_. The furrows wrought by this last-named stratum on the bottom of the glacier-channels show the wonderful force of friction which the glacier exercises during its descent. The depths of these furrows depends entirely on the hardness of the débris carried down by the glacier, and the nature of the rocks submitted to the friction. The polish assumed by these rocks when they are sufficiently solid to resist the thunderous march of the glacier, indicates the enormous pressure which it exercises on the slopes of the valley through which it forces its way. This effort, bearing principally on the side of the rocks turned in the direction of their crests, impresses upon them a peculiar rounded form, so like the appearance of a flock of sheep (_moutons_) that De Saussure gave them the name of _roches moutonnées_. Connected with the scientific evidence of the progressive movement of glaciers, a glacier in the Bernese Oberland will for ever be memorable. Two branch glaciers, the Lauteraar and the Finsteraar, unite at a promontory called the Abschwung to form the trunk-glacier of the Unteraar, which carries a great medial moraine along its colossal back. Here in 1827, an “intrepid and enthusiastic” Swiss professor, Hugi, of Solothurm (or Soleure), erected a small cabin of stones for the purpose of observations upon the glacier. The hut moved, and he took steps to measure its motion. In three years, 1827 to 1830, it moved 330 feet downwards. In 1836 it had descended 2354 feet; and in 1841, it had accomplished a journey of 4712 feet. [This was at the rate of about 336 feet a year.]