CHAPTER IV. 



THE EASTEE]^ SECTIOK 



GENERAL TOPOGRAPHICAL FEATURES, DRAINAGE, ETC. 



So far as relates to the somewliat partial nature of the geological ex- 

 aminations in the region to the east of the Teton Eange, it may be made 

 to embrace a belt of territory nearly coextensive, north-south, with the 

 extent of Jackson's Basin along its western border, or about 40 miles ; 

 a line carried east from Jackson's Lake, along the divide between Buf- 

 falo Fork and the sources of the main Snake Eiver, to the continental 

 watershed, defining its northern hmits. To the south and east of the 

 above boundaries, in the interior portion of the area, our examinations 

 were merely such as it was possible to make from commanding mount- 

 ain summits, by which means, in perhaps the majority of cases, it was 

 possible to gain, at least, a general knowledge of a much wider extent 

 of country than that actually visited. 



By far the larger portion of this area belongs to the drainage of the 

 Columbia, and, hydrographically, it is further divided into three well- 

 defined subsections, viz, the southern, including the area north of Ho- 

 back's Eiver and south of the Gros Ventre Eiver ; the middle, or that 

 between the Gros Ventre and Buffalo Fork ; and the northern, a belt of 

 country embraced between the latter stream and the extreme eastern 

 sources of the Snake. The Buffalo Fork and Gros Ventre, both beauti- 

 ful, well-sized mountain streams, rise in the continental divide, and flow- 

 ing westward join the Snake in its passage through Jackson's Hole. 

 The Gros Ventre drains the larger area, but Buffalo Fork is, perhaps, 

 scarcely inferior in the volume of its waters. In respect to Hoback's 

 Eiver and the country along the southern flank of the Gros Ventre 

 Mountains, which it in part drains and which in part belongs to the 

 Green Eiver drainage, our information is as yet wholly based on such 

 accounts as have reached us from the hunters and explorers, who have 

 casually visited or passed through that region with other objects in view 

 than its careful exploration. 



In surface reliefs the three above-mentioned subsections differ greatly 

 one from the other ; and this difference, as we shall see presently, is due 

 to the geological features characteristic of the several quarters, and 

 which will be taken up in connection with the description of these areas. 

 In the northeast, a narrow belt east of the continental watershed, on 

 the headwaters of Wind Eiver, was visited in the course of the season, 

 where we had opportunity to extend our general examinations south- 

 ward as far as Union or Warm Water Pass, and thence along the north- 

 east foot of the Wind Eiver Mountains. This opportunity, notwith- 

 standing the limited -time a hasty passage through the country afforded, 

 enabled the acquisition of many interesting details and a general laiowl- 

 edge of the geological relations of the orographic features of this ])arfc 

 of the great watershed, and which find so diverse expression in the 

 grandeur and unity of the great displacement out of whose metamor- 

 phic axis were fashioned the chain of snowy peaks and labyrinth of am- 



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