The constant heavy pressure on the glacial ice, and the tension resulting from obstacles in the channel followed by it, cause splits of large masses to occur, and force them so far to separate that there is no chance of regelation. These splits are the _crevasses_ met with in many glaciers, and one of the most dangerous features to climbers, especially when they are concealed by a treacherous coating of snow. The transverse crevasses are so close together and form such a bewildering labyrinth that it requires a good pilot and experienced guide to steer clear of their difficulties. In proportion as the glacier develops, these crevasses or fissures enlarge. Some of them form into deep valleys, abysses, and unfathomable gulfs. If one falls into a crevasse, it is alleged he hears everything that is said above him, but cannot make himself heard. The ice of these fissures has tints of extraordinary fineness and delicacy; it is of a pale and tender blue, but if you detach a piece to examine it in full light, its beautiful ideal blue color disappears, and you have nothing in your hand but a pale, colorless block. The crevasses, at times all lined with the purest, smoothest snow, open up like great alcoves, hung in clouds of ice with delicate ornaments thrown on them by the wind. They modify and change every spring, when the winter’s accumulation of snow melts under the action of the heat, and the frost of the nights incorporates it with the glacier. The guides, therefore, before conducting parties at the beginning of the season, sound the old crevasses, and study the new features of the glacier, its curves, its bridges of snow suspended in the air, its abysses covered with a frail surface, its fantastic architecture of staircases and terraces of ice. The glacier ice, made of annual beds disposed in vertical bands of white and blue, does not resemble ordinary ice, which is homogeneous throughout; it is granular, traversed by a multitude of small canals, by a net-work of veins in which a bluish water circulates, and which penetrates the whole thickness of the ice. The water that escapes from a glacier is either black, like ink, or green, like absinthe, or white, like milk; it is always troubled, and charged with mud or earth full of fertilizing matter. So, while the glaciers make the higher valleys into a land of desolation and misery, lower down on the slopes that drink life from its flood, it is a garden, an orchard, a rich vine country, smiling hill-sides, shaded with trees and crowned with flowers. While a glacier is a stream of ice, it is not formed of frozen water, but of frozen snow. The snow of the mountain-top is a fine dry powder, which is formed into a granular mass by the action of the sun shining on it in the middle of the day; what is thus partially melted quickly freezes again each evening into globular forms, consequently a glacier is not slipping like ordinary ice. This process has gone on for unknown ages.