Then comes the start, and the cavalcade files off into the virgin forest, led by the headman, whose business it is to pick out a trail amidst the dense undergrowth and the fallen trees along which the pack train can go. Soon the sound of the axe is heard, and the single file of ponies comes to a standstill whilst some fallen tree which bars the way is cut through. Sometimes the path leads along the bank of a swiftly flowing, muddy white river, swollen by the melting snows of the glaciers, which every now and then are seen through more open parts of the forest, glaciers that glimmer and shine high up amongst the peaks that wall in the valley below. It is in places such as this that the greatest danger to the horses and baggage is experienced. The banks of the river may be rotten, or a horse more self-willed than the others may suddenly plunge into the water, and often it is next to impossible to prevent others following; so that in one moment of time perhaps half the outfit may be sweeping down stream to perdition, and the expedition ruined by being left provisionless. Fortunately, although I have often seen our horses helplessly drifting down rivers that at first sight seemed hopeless to get out of, owing to the undercut banks, depth of water, and strength of current, yet somehow or other these plucky little ponies always have managed to scramble out again. The silent forests, through which one sometimes has to march for days together, are not so dense, and the trees are not so large on the eastern side of the Divide as on the western, that is to say, in the valleys leading to the Columbia river.