359. On the two main tributaries we also notice moraines which seem in each case to rise from the body of the glacier, appearing in the middle of the ice without any apparent origin higher up. These at their sources, are sub-glacial moraines, which have been rubbed away from rocky promontories entirely covered with ice. They lie hidden for a time in the body of the glacier, and appear at the surface where the ice above them has been melted away by the sun. 360. This is the place to mention a notion long entertained by the inhabitants of the high Alps, that glaciers possess the power of thrusting out all impurities from them. On the Mer de Glace you and I have noticed large patches of clay and black mud which evidently came from the body of the glacier, and we can therefore understand how natural was this notion of extrusion to people unaccustomed to close observation. But the power of the glacier in this respect is in reality the power of the sun, which fuses the ice above concealed impurities, and, like the bodies of the guides on the Glacier des Bossons (143), brings them to the light of day. 361. On no other glacier will you find more objects of interest than on the Görner. Sand-cones, glacier-tables, deep ice-gorges cut by streams and bridged fantastically by boulders, moulins, sometimes arched ice-caverns of extraordinary size and beauty. On the lower part of the glacier we notice the partial disappearance of the medial moraine in the crevasses, and its reappearance at the foot of the incline. For many years this glacier was steadily advancing on the meadow in front of it, ploughing up the soil and overturning the chalets in its way. It now shares in the general retreat exhibited during the last fifteen years among the glaciers of the Alps. As usual, a river, the Visp, rushes from a vault at the extremity of the Görner glacier. § 53. _Ancient Glaciers of Switzerland._ 362. You have not lost the memory of the old Moraine, which interested us so much in our first ascent from the source of the Arveiron; for it opened our minds to the fact that at one period of its history the Mer de Glace attained far greater dimensions than it now exhibits. Our experience since that time has enabled us to pursue these evidences of ice action to an extent of which we had then no notion.