YELLOWSTONE, a river of the United States; rises in a beautiful lake of the same name high up in the Rocky mountains, and receiving numerous branches from the s., flows north-easterly through the territory of Montana, and empties into the Missouri river, in the n.w. part of Dakota territory, lat. 48° 5' n., long. 104° west. It is 800 yds. wide at its mouth, 1000 m. long, and navigable 700 or 800 miles.
The region of the Yellowstone and its source was for the first time explored by par ties from the United States in 1870-71, and seems to be one of the most wonderful spots in the earth. Making their way up the river through the grand scenery of the Rocky mountains, the explorers came to a district of a square mile in area, filled with hot springs in active operation, which cover the hillsides with snowy white deposit like a frozen cascade. Three or four miles around were occupied by springs which have ceased to flow. They are about 6,000 ft. above the sea, and are already resorted to by invalids. This was but the beginning of the wonders. Next they came to a terrific rift, 2,000 ft. in depth, with a river rolling- in its deeps, " a grand, gloomy, terrible place." At the head of this arc the Tower falls, with a sheer descent of 400 ft. The Grand
canon, however throws, this into the shade. This fearful abyss is 3,000 ft. in perpen dicular height, and to one looking up from the bottom, stars are visible in broad day light. The ravine is full of hot springs of sulphur, sulphate of copper, alum, steam jets in endless variety, some of most peculiar form. The grandeur of the canon is at once heightened and diversified by the Upper and Lower falls; the latter one unbroken sym metrical expanse, 350 ft. in height. Between this fall and the lake lies a region full of boiling springs and craters, with two hills 300 ft. high, formed wholly of the sinter thrown from the springs. Further on is a valley containing about 1500 geysers, some throwing up immense columns of water to the height of more than 200 feet. The beautiful lake from which the river issues is about 300 sq.m. in area, and is situated 7,427 ft. above the level of the sea. In 1872 the region at the source of the Yellowstone, 65 m. long by 55 m. broad, including the Grand canon and the lake, was reserved by congress from occupancy, and set apart as a `^public park or pleasuring-ground for the benefit and enjoyment of the people."