Much of the country is semi-desert, but some of it is as green as the valley of the Nile. In places the hills, sloping almost precipitously back from the river, are wrinkled with dry waterways filled with scrubby forests. In others there are series of ledges rising one over the other, making great terraces from the edge of the stream to the tops of the mountains. The Yukon changes its course like the Yellow River of China. Now we pass through gorges of silt where the sand walls rise above us to the height of a twenty-story office building; and now swing around beds where we seem to be walled in by the cuttings made by the water. The hills are composed of earth washings, and from year to year the snaggy teeth of old Father Time have been gouging long furrows out of their sides. These furrows have caught the moisture, forests of small evergreens have grown up in them, and the landscape for miles looks as though it had been ploughed by the gods and drilled in with these crops of green trees. This makes the country, when seen from a distance, seem to be cultivated. There is a scanty grass between the patches of forests, and the whole is like a mighty farm planted by the genii of the Far North. As we go down the river the scenery changes. Here the banks are almost flat and are covered with bushes. There on the opposite side they are of a sandy glacial alluvial formation, perfectly bare. At times the soil is so friable that it rolls down in avalanches, and a blast from our steam whistle starts the sand flowing. It makes one think of the loess cliffs on the plains of North China. Those cliffs contain some of the richest fertilizing matter on earth, and their dust, carried by the wind, enriches the country upon which it drops as the silt from the Abyssinian highlands enriches the Nile Valley. The soil from the upper Yukon, on the other hand, is poorer than that which surrounds the Dead Sea at the lower end of the Jordan. It lacks fertilizing qualities, and some of it rests on a bed of prehistoric ice, which carries off the rainfall, leaving no moisture for plant life. A geological expert in our party says it is as though the land were laid down on plates of smooth copper tilted toward the valleys to carry the rain straight to the rivers. He tells me that the region has only ten or twelve inches of water a year, or a rainfall similar to that of California in the neighbourhood of Los Angeles. He says also that sixty-five per cent. of the water that falls finds its way to the streams. [Illustration: The upper Yukon River in places is only a few hundred feet from bank to bank, and in others as wide as a lake. Throughout most of its length it is dotted with islands in all stages of formation.] [Illustration: The Yukon twists and turns in great loops and curves throughout its entire length, and at Five Finger Rapids presents a stretch of water that can be navigated only by the exercise of the utmost skill in piloting.]