GEOLOGICAL SUEVEY OF THE TEEEITOEIES. 215 



twenty-five degrees, and, the eastern flank diverging a little more rap- 

 idly tiian the western flank, the two approach, narrowing the width of 

 the belt toward the north. While this is true as a general statement, 

 it must not be supposed that in attempting to follow it out in detail 

 we shall find any great uniformity, for we shall proceed but a comjiara- 

 tively short distance up the western flank until we encounter the rugged 

 Salmon Eiver Mountains, pressing against the belt at its narrowest 

 point like a huge goiter upon the neck. But the most interesting group 

 within this part of the belt is to be found in the northwestern part of 

 Wyoming, which has been the objective point of the present year's expe- 

 dition, and of which a very full and deeply interesting account will be 

 found in Professor Hayden's report of the present year, and to which 

 this report forms an appendage. I shall, therefore, "refer to it only so 

 far as its features bear upon the agricultural resources of the surround- 

 ing regions ; and, moreover, although xDassing closely around the west- 

 ern and northwestern flanks, and crossing the axial range at its western 

 exit, I did not in person visit the magnificent scenery immediately sur- 

 rounding Yellowstone Lake, which lies near the central point of the 

 group. 



The northern limb of the Wahsatch Eange, separating the waters of 

 Green Eiver from those of Bear and Snake Elvers, penetrates northward 

 near the western border of Wyoming Territory. Wind Eiver Eange, 

 stretching northwest from South Pass, rising in altitude as it advances 

 until it culminates in Fremont's Peak, forms the divide here between 

 the waters of the Atlantic and Pacific, represented by Green and Wind 

 Elvers. The west branch of the Big Horn Mountains, reaching across 

 the Wind Eiver Valley, leaving a deep gorge for the passage of this 

 stream, directs its course toward the same central point; and the main 

 Bocky Mountain Eange from the north here bends its course eastward 

 to connect with the others at the great point of union. In other words, 

 here is the culminating point of the great northwestern mountain belt, 

 from which radiate not only its chief mountain ranges, but also, as a 

 natural consequence, the principal streams of the section. The Big 

 Horn, Yellowstone, Madison, Green, and Snake Elvers all have their 

 origin here, the first three finding an outlet for their waters through 

 the Mississippi to the Gulf of Mexico, the next through the Colorado 

 of the West to the Gulf of California, and the last through the Columbia 

 to the Pacific Ocean, three thousand miles from the exit of the first. 

 Here, amid a collection of the most wonderful scenery on the continent, 

 is found the chief radiating point of the water-systems of the Northwest, 

 being equaled in this respect only by the mountain group of Colorado 

 Territory. A result naturally to be expected from this formation fol- 

 lows, viz, an abundant supply of never-failing streams. It is also inter- 

 esting, on account of the influence it has upon the course of the minor 

 streams, to notice the obstinate tendency of the minor ranges to main- 

 tain the north and south direction so common in Territories south and 

 in the Salt Lake Basin. The Teton Eange, between Henry's Fork and 

 the main branch of Snake Eiver, the northern arm of the Wahsatch, 

 the main range of the Big Horn Mountains, between the waters of 

 Big Horn and Powder Elvers, and even the ridge separating the two 

 branches of the latter stream, though varying much in character, all 

 have this course almost direct. If we pass north of the group into the 

 southern part of Montana, we find this holds good with respect to the 

 ridges which separate the tributaries of the Upper Missouri. The 

 divides between Stinking Water and the Madison, between Madison 

 and Gallatin, and between Gallatin and the Yellowstone, all preserve 



