FLORA OF THE YELLOWSTONE NATIONAL PARK. 7 



the southwest, and the other turning to the northward forms a 

 narrow divide between the Madison and Yellowstone, and 

 broadening out, again divides, one branch sweeping around to the 

 head of the Grand Canon, and the other, much broken by lateral 

 and transverse drainages, continuing northward nearly to the 

 Mammoth Hot Springs. The low semicircular depression thus 

 formed on the west bank of the Yellowstone, is known as 

 Hayden Yalley, and has formed a portion of the ancient 

 Yellowstone Lake. It is drained mainly by Alum Creek. 



At the head of the Grand Canon are the Upper and Lower or 

 Great Falls of the Yellowstone, half a mile apart; they are 108 

 and 309 feet in height. East of Alum Creek is the region of 

 Sour Creek, broken by low, heavily timbered ridges, extending 

 to Mirror Lake Plateau on the east. North of the Grand Canon 

 is the crescent-shaped Mt. Washburne Range, the opening towards 

 the Yellowstone River, and drained by Tower Creek. The 

 interior slopes of this crater-like area and the rh3 r olite plateau 

 along Tower Creek are densely timbered, except about Antelope 

 Creek. Broad and Deep Creeks, which have cut deep canons in 

 the plateau, enter the Yellowstone east of Mt. Washburne, and 

 north of these are the slopes of Amethyst Mountain and Speci- 

 men Ridge. The East Fork, the main branch of the Yellowstone, 

 joins it from the east about twenty miles above where the Yellow- 

 stone crosses the northern boundary of the Park at its junction 

 with the Gardiner River. This portion of the main river is 

 called the Third Canon. It has little of the well-defined walls 

 of the Grand Canon. On the east rise precipitous granite slopes 

 several thousand feet. On the west the country is much lower 

 and has more of a plateau character, and here about Blacktail 

 Deer Creek and on Mt. Evarts, are large grass-covered areas, 

 interspersed with groves of timber, and extending, in some cases, 

 up the northern slopes of the Mt. Washburne amphitheatre. 

 The East Fork from its junction with the Yellowstone to Cache 

 Creek about sixteen miles runs through an open grass- 

 covered valley from 1-1^ miles in width. Its main branches 

 Slough, Soda Butte, Cache, Calfee and Miller Creeks, flow from 

 the east, draining the Yellowstone Range. On the west it receives 

 numerous small drainages from Specimen Ridge and the Mirror 

 Lake Plateau. On both sides, as far as Cache Creek and above 



