YUKON RIVER. One of the largest rivers of North America. Tt is formed at Fort Selkirk, Yukon Territory, Canada, by the junction of the Lewes and Pelly rivers, and flows northwestward into Alaska, which it traverses in a southwest direction, finally turning west and emptying into the Sea through a large delta on the south shore of Norton Sound (Map: Alaska, D 3). Its total length, including the Lewes, is, according to a recent report of the United States Geological Survey. 1865 miles. The Lewes, which is generally considered the upper course of the main stream, rises in a cluster of lakes (Linde man, Bennett) in the extreme northwestern cor ner of British Columbia and on the no•thern foot of the Chilkoot Pass and flows northward to the Pelly confluence at Fort Selkirk. The upper courses of the rive• and its tributaries generally flow through narrow valleys inclosed between mountains of moderate elevation, and in some places taking the form of canons. In Alaska the river flows for hundreds of miles through level, moss-covered tundras, where the width, between its low, marshy banks, is from one to two miles, though its depth is not great. The delta is of vast extent, having an area, including the por tion inclosed by the Kashimuk arm, of 9000 square unites. The volume of discharge of the Yukon has been thought to be fully two-thirds that of the Mississippi, and great quantities of sediment are brought down. There arc 26 out lets over 200 yards wide and numerous smaller channels. All of them, however, are silted np,
with a depth of only two to nine feet on the bars, while the sea for many miles from shore is only a few feet deep. Sea-going steamers can not, therefore, enter the river, but proceed to the ha rfim. of Saint Michael, about 70 miles to the north, where they unload into stern-wheel steamers, many of them of majestic size. which ply regularly in summer to Dawson. A fleet of "upper river" steamboats runs between Da wow and the White Horse Rapids, where a portage effects a union with the third section of river navigation—from Miles Canon to Bennett. Nav igation is continuous (although hampered by rapids) between the White Horse and the mouth of the river. The current is over most parts very swift., and the descent very rapid. From Dawson to the sea, about 1400 miles, the fall is on the average nearly a foot per mile. The navigation of the whole river is free to Canadian vessels; the navigable season is comprised be tween the months of June and September or October. The chief settlement on the Yukon is Dawson, at the confluence of Klondike Creek, the centre of the gold-mining region. The largest tributaries join the main stream in Alaska. They are the Porcupine, the Koyukuk, and the Tanana. See YUKON GOLD-FIELDS. For bibliography see ALASKA.