6 FLORA OF THE YELLOWSTONE NATIONAL PARK. 



east, and over 11,000 feet on the southeast. The continental 

 divide crosses the Park in its southwestern part, and is generally 

 broad, ill-defined, and heavily timbered throughout. It has an 

 elevation of from 8000-9500 feet, at one point but 150 feet above 

 Yellowstone Lake. 



On the western slope of the divide are the tributaries of the 

 Snake River — the Lewis Fork of the Columbia — and on the 

 eastern tliose of the Missouri ; the latter including the Marlison 

 and East Gallatin on the west and northwest, the Stinkingwater, 

 a tributary of the Big Horn, on the southeast, and the Yellow- 

 stone River. The latter, which drains more than half (2000 sq. 

 miles) the area of the Park, enters at the southeast corner at an 

 elevation of 7900 feet, and flowing about northwest through 

 Yellowstone Lake and the Grand Carion, crosses the northern 

 boundary at an altitude of 5800 feet. Yellowstone Lake (7740 

 feet), the largest lake at great elevation in North America, has a 

 length and breadth of respectively twenty and fifteen miles, a 

 depth of 300 feet, and an area of 150 square miles. The shore 

 line, indented by several large bays, is over 100 miles. 



The beautiful curves of the sandy beaches and crystal purity 

 of its waters, make it an object of unusual interest. With the 

 exception of the Yellowstone Range, rising from its eastern 

 shore, it is surrounded by a generally low, heavily timbered 

 country. A few miles southwest on the opposite slope of the 

 continental divide, are the little gems of Heart, Lewis, and 

 Shoshone Lakes, varying in length from three to six miles. 



The Yellowstone River, from the southern boundary to the 

 lake — fifteen miles — is a sluggisli, tortuous stream, bordered by 

 meadow and swamp two miles in width. The slopes down to the 

 valley are bold and precipitous, the surrounding country being 

 a high volcanic jilateau of 10,000 feet altitude, and over. The 

 spurs of the Yellowstone Range making down to the lake are 

 heavily timbered, begoming less so towards the south. Pelican 

 Creek, draining the south end of Mirror Lake Plateau, enters 

 the lake near the outlet. Meadows from a half to a mile in width 

 border the lower portion of its course. At the outlet of Yellow- 

 stone Lake on the west abuts the heavily timbered i^lateau of the 

 Elephant Back (8500 feet), which running westward a few miles, 

 splits into two parts, one merging into the continental divide on 



