When heavy winter snow falls in the Alai valley, the wolves return to the higher wilds of the Pamir where the snow lies less deep, and here they chase the wild sheep, _Ovis Poli_, as it is named after its discoverer, Marco Polo. It has large, round, elegantly curved horns and is somewhat larger than the wild sheep of Tibet. The wolves chase Marco Polo's sheep by a cunningly devised method. They hunt up a herd and single out some less cautious or less quick-footed member. This animal is forced by a watch posted ready beforehand to take refuge on a projecting rock which is surrounded by wolves. If they can get up to the sheep they take him easily, but if not, they wait till his legs give way with weariness and he falls into the jaws of his pursuers. Many a time I have met wolves in various parts of Asia, and many sheep, mules, and horses of mine have they destroyed. How often has their dismal howl sounded outside my tent, as though they were calling for my flesh and blood! We had ridden 300 miles when we came to a small Russian frontier fort which rears its simple walls on the middle of the "Roof of the World," beside one of the headwaters of the Amu-darya. On the other side of the frontier lies the Eastern Pamir, in the dominion of the Emperor of China. "THE FATHER OF ICE-MOUNTAINS" Wherever one may be in the Eastern Pamir one sees the Mus-tagh-ata, the "Father of Ice-Mountains," rear its rounded summit above all the other peaks (see map, p. 56). Its height is 25,800 feet, and accordingly it is one of the loftiest mountains in the world. On its arched crest snow collects, and its under layers are converted by pressure into ice. The mountain is therefore crowned by a snow-covered ice-cap. Where there are flat hollows round the summit, in these also snow is piled up as in bowls. It glides slowly down with its own weight, and by pressure from above is here also converted into ice. Thus are produced great tongues of ice, which move downwards exceedingly slowly, perhaps only a few yards in the year. They are enclosed between huge steep ridges, from which time after time gravel and blocks of stone fall down on to the ice and are carried down to lower levels. The further the ice descends the warmer becomes the air, and then the ice melts in the sun. As it melts below, the stream of ice is forced down from above, so that its lowest margin is always to be found in the same place. The gravel and boulders are brought down thither and piled up together so as to form great mounds and ridges, which are called moraines. The ice-stream itself is called a glacier. Many such tongues of ice fringe Mus-tagh-ata on all sides. They are several miles long and half a mile to a mile broad. The surface is very uneven and consists of innumerable knobs and pyramids of clear ice.