Then, besides, you can actually hear the glaciers moving when you stand upon them. It is sometimes very difficult to get upon them; for at the sides where the ice rubs against the rocks, immense chasms and fissures are formed, and vast blocks both of rock and ice are tumbled confusedly together in such a manner as to make the way almost impracticable. When, however, you fairly get upon the ice, if you stand still a moment and listen, you hear a peculiar groaning sound in the _moraines_. To understand this, however, I must first explain what a moraine is. On each side of the glacier, quite near the shore, there is usually found a ridge of rocks and stones extending up and down the glacier for the whole length of it, as if an immense wall formed of blocks of granite of prodigious magnitude had been built by giants to fence the glacier in, and had afterwards been shaken down by an earthquake, so as to leave only a confused and shapeless ridge of rocks and stones. These long lines of wall-like ruins may be traced along the borders of the glacier as far as the eye can reach. They lie just on the edge of the ice, and follow all the bends and sinuosities of the shore. It is a mystery how they are formed. All that is known, or rather all that can be here explained, is, that they are composed of the rocks which cleave off from the sides of the precipices and mountains that border the glacier, and that, when they have fallen down, the gradual movement of the ice draws them out into the long, ridge-like lines in which they now appear. Some of these moraines are of colossal magnitude, being in several places a hundred feet broad and fifty or sixty feet high; and, as you cannot get upon the glacier without crossing them, they are often greatly in the traveller's way. In fact, they sometimes form a barrier which is all but impassable. The glacier which most impressed Mr. George and Rollo with its magnitude and grandeur was one that is called the Sea of Ice. It is called by this name on account of its extent. Its lower extremity comes out into the valley of Chamouni, the beautiful and world-renowned valley, which lies near the foot of Mont Blanc. In order to reach this glacier, the young gentlemen took horses and guides at the inn at Chamouni, and ascended for about two hours by a steep, zigzag path, which led from the valley up the sides of the mountain at the place which formed the angle between the great valley of Chamouni and the side valley through which the great glacier came down. After ascending thus for six or eight miles, they came out upon a lofty promontory, from which, on one side, they could look down upon the wild and desolate bed of the glacier, and, upon the other, upon the green, and fertile, and inexpressibly beautiful vale of Chamouni, with the pretty little village in the centre of it. This place is called Montauvert. There is a small inn here, built expressly to accommodate travellers who wish to come up and go out upon the glacier.