Here you are on a ledge of rock that juts over a valley, hundreds of feet above it. In front of you are the upper reaches of the Sawtooth Range of mountains, one of the wildest and most glorious spots in North America. Across the valley, less than a mile away from you, the great, rugged peak of Mt. Sir Donald shoulders into the sky. About its top a snowstorm is gathering. On its rough sides lie great snow fields, which form into glaciers farther down the cliffs. Here are grouped in small compass the great forces of nature that are at work constantly in high mountain ranges. The scarred sides of the mountain peak is our first point of interest. You will observe that great point of interest. You will observe that great slices of the rock have been broken off, leabing gashes that look like ugly scars. This wearing away is due to heat and cold, and the action of the wind and moisture. On the

side of the slope nearest you there has been built up a great field of stones that have been torn loose from the mountains. The clouds clustering about the mountain's top are laden with moisture. In the lowlands cooling would condense this moisture in the form of rain. At this height the atmosphere is so cold that moisture falls only in the form of snow or hail. This accounts for the snow fields, and the glaciers that they built up. From the foot of each of the glaciers trickles a countless number of streams, which unite to form the swift mountain river in the valley far below. In spite of the snow fields about us, we are comfortably warm at our observation post. The woman foes not even wear a coat. Mount Sir Donald is 10,880 feet above sea level. It is in the Selkirk Mountains.