Far below, and heading close under the sharp crest of the range, are densely wooded canons. The fair weather is passing, and it is necessary to find the trail and descend. Clouds are sweeping across the ridges and peaks, and soon the whole summit will be covered by them. From a point a little east of the summit the clouds present a grand sight at the gathering of a storm. Higher and higher they pile upon the ocean face of the mountains. At the bottom they are dark and threatening, but the thunder-heads above can be seen bathed in the bright sunlight. For a time the clouds hang upon the summit as if stopped by some invisible barrier; perhaps they are loath to pass into the drier air of the eastern slope. But finally they move on, and rain or snow soon envelops the whole landscape. The trail descends rapidly for four thousand feet to Cascade River, a tributary of the Skagit. It is a steep and slippery way, and in many places it is not safe to ride the horses. The sub-arctic climate of the summit is left behind, and one is soon surrounded by dense and luxuriant vegetation. Such a change as this, in a short distance, shows how greatly elevation affects climate and plant growth. Upon every hand there is the sound of rushing water. From the cliffs ribbon-like cascades are falling. The rivulets unite in one stream, which roars and tumbles down the canon over logs and boulders. The trail crosses and recrosses the torrent until the water becomes too deep for fording, and then it leads one to a rude bridge made of two logs with split planks laid across them. As the canon widens, the trail leads farther from the river and through dense forests. The woods are so silent that they become oppressive, and the air is damp, for the sunlight is almost excluded. The tall trees, fir, hemlock, and spruce, with now and then a cedar, stand close together. Shrubs of many kinds are crowded among them, while mosses and ferns cover the ground. The fallen trunks are wrapped in moss, and young trees are growing upon them, drawing their nourishment from the decaying tissues. In the more open spots grow the salal bushes with their purple berries, the yellow salmon berries, and the blue-black huckleberries.