REPORT OF THE GEOLOGICAL FIELD-WORK OF THE TETON 



DIVISION. 



By Orestes St. John. 



CHAPTER I. 



AREA AND BOUNDARIES. 



The district of the T6ton or northern division of the United States 

 Geological and Geographical Survey is bounded as follows : Commencing 

 at the southwestern corner on the eastern margin of the Snake Plains, in 

 the vicinity of Mount Putnam, on the parallel 43° north latitude, the 

 western boundary of the district follows the meridian 112° 15' west lon- 

 gitude north to the intersection of the parallel 44° 15' ; thence the north- 

 ern boundary extends east to the meridian 109° ; thence south to the 

 parallel 43°, which latter forms the southern boundary of the district. 

 Of this area, which forms a rectangle of one and a quarter degrees of 

 latitude and two and three-fourths degrees of longitude, about 6,000 

 square miles were actually worked topographically from stations com- 

 manding extensive stretches of plateau and plain. A broken region in 

 the southeastern quarter shading off into the upper portion of Green 

 River Basin along its southern border, and embracing a part of the Gros 

 Ventre Mountains, and a considerable portion of the Snake Biver Bange 

 in the region of the Grand Canon, with a strip on the eastern border 

 including the northern half of the Wind Biver Bange, was, for lack of 

 time and interruption, left unworked. 



One of the earliest accounts of the region embraced within the above- 

 mentioned limits is found in the published journal of the missionary 

 Bev. Samuel Parker,* who, in the summer of 1835, performed an ardu- 

 ous journey across the continent to the Columbia. The missionary, as 

 nearly as can be made out, probably entered the country comprised in 

 the present account either through Hoback's Canon or some pass to the 

 northeast in the Gros Ventre Bange, passing into Jackson's Hole, and 

 thence crossing the T6ton Pass at the southern end of the range of the 

 same name, into Pierre's Basin. This route probably closely corresponds 

 to that pursued by the early fur-traders, of which Irving has preserved 

 accounts in his "Astoria " of the passage of Mr. Wilson G. Hunt, in 1811, 

 and of Bobert Stewart the following year, on their return across the 

 mountains from the Columbia. Mr. Parker's geological notes are in the 

 main easily identified in the localities in this region. 



The War Department expedition, under command of Capt. W. F. Bay- 

 nolds, visited this country in the summer of 1860, and to the report of 

 Dr. F. V. Hayden, published in 1869, who was commissioned geologist 

 of the expedition, we owe the first authentic account of the geological 

 structure of a large extent of country surrounding the sources of the 

 Missouri and the Columbia Bi vers. This expedition passed up the Wind 

 Biver Valley, crossing the range of the same name over Union or Warm 

 Water Pass, and thence descended the Gros Ventre to Jackson's Hole. 



*. Journal of an exploring tour beyond the Rocky Mountains, 4th ed., Ithaca, N. Y., 

 1644. 



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