But if the ice masses in the shady glens and under the old moraines may be said to be pieces of the Ice Age left over, the glaciers of to-day are, in a sense, the Ice Age itself. For these glaciers do, on a smaller scale, what Mr. Labrador and his partners in northern America, Europe, and Asia did on a large scale so many centuries ago. Suppose now, like Agassiz, we trace a glacier to its source. It will be a long journey, all steep, some of it almost straight up, and along chasms of slippery ice with sudden storms that hide the chasms and blind your eyes and take away your breath. The first part of our journey is over a field of ice, gray with the dirt of weathered rock from the mountain sides. Along its borders are those sharp-edged stones neatly packed in rows, that our geography tells us are called "lateral moraines." It has another row of these stones sticking up right in the middle of its back, like the sharp-pointed vertebræ of the ceratosaurus. By noon, as often happens in the Alps as elsewhere at this time of year, a rain comes up and we lunch under the shelter of a tumbled heap of rocks. Watching the downpour drift across the desolate wastes we think what jolly times like this Agassiz and his companions had in their little hall of science under the big stone. After lunch we start again, and although it's stiff going, and it takes a lot of this thin air to make one good breath, we spare a little, now and then, for shouting, to hear the wonderful play of the echoes among the mountains. We go through all kinds of weather--rain, mist, snow. Then suddenly we burst into blinding light. The sun is so dazzling on the snow, now no longer covered with dirt and mountain débris, that we must all put on our colored glasses. In some places, among bare rocks that absorb the sun's heat, it is positively sultry. The fields around us look like an ocean turned to stone. Waves are formed in the surface ice of the glacier because surface ice moves faster than the main mass beneath. On the bordering mountain walls the ice rises into still greater waves "foaming about the feet of the dark central crests like the surf of enormous breakers." And this great, still image of the parent sea, from which the air currents carried the moisture that made it, has eddies and whirlpools, and like the troubled sea, "whose waters cast up mire and dirt," the glacier, where it swirls along its shores, works pebbles and dirt to the surface. Often this material is carried into the centre of a whirl, as sea weeds and the rubbish of the seashore are driven into eddies among the rocks.