250 GEOLOGICAL SURVEY OF THE TERRITORIES. 



other Territories we find the difference much greater than woukl be an- 

 ticipated. For this purpose I give here the elevations of a few i)oints : 



Feet 



Albuquerque, New Mexico 5, 032 



Santa F6, New Mexico. . 6, 840 



Denver, Colorado 5, 300 



Green Eiver, at the railroad (Crossing 0, 140 



Salt Lake City . . . =. 4, 350 



The Humboldt Sink 4, 017 



Port Laramie 4, 519 



Sweet Water Eiver, at Independence Eock 5, 998 



South Pass Citv ^ 7, 857 



Port Hull, (about) 4, 200 



From this we see that even the lowest point of the Great Basin, near 

 the ''Humboldt Sink," is 1,120 feet above the mouth of the St. Eegis de 

 "Borgia and 733 feet above Port Owen. This very important fact in 

 regard to the phj'sical geography of this Territory will serve as an ex- 

 planation of its comparatively mild climate, notwithstanding its north- 

 ern latitude. 



The entire Territory may be divided into four sections, each having 

 its water system and natural boundaries tolerably well defined, as fol- 

 lows: The northwestern, which includes all that portion lying between 

 the Eocky Mountain and Bitter-Eoob Eange; the southern, which is 

 drained by the three forks of the Missouri; the southeastern, which is 

 drained by the Yellowstone*, and the northern, which includes the val- 

 leys of Milk and Missouri Eivers, and the bordering plains. Mr. Gran- 

 ville Stuart designates a fifth basin, embracing the country drained by the 

 Boulders and the lower i^ortion of the Jefferson ; but for the present 

 I)urpose, the foregoing division is probably the best, his fifth basin being 

 considered as a portion of the southern section. 



THE NORTHWESTERN SECTION. 



This section, as before stated, is situated between the Eocky Mount- 

 ain Eange on the east and the Bitter-Eoot and Coeur d'Alene Mount- 

 ains on the west, extending from the fort3'-sixth parallel of latitude to 

 the British possessions, and including ail of Missoula County and the 

 southern half of Deer Lodge County. It is about one hundred and fifty 

 miles wide and two hundred miles long, containing an area of thirty 

 thousand square miles ; and is traversed from southeast to northwest 

 toy Clark's Pork of the Columbia, and its leading tributaries. 



The northern part is variable in character, having some open prairie 

 country and valleys of limited extent, while much of it is broken and 

 rugged and covered with heavy pine forests. It is drained by Plathead 

 Eiver, which has three leading tributaries — Maple Eiver, coming from 

 the northwest; Plathead, from the north ; and another branch from the 

 northeast. Near the forty-eighth i)arallel this stream expands into a 

 beautiful lake about thirty miles long and ten or twelve miles wide. 

 Below this it is of considerable size, flows in a southwest direction for 

 ribout fifty miles, and joins the Missoula, the two forming Clark's Pork.* 



*Tlie main brancli of this stream has a number of different names. From the junc- 

 tion of Deer Lodoje and Little Blackfoot Eivers to the mouth of Big Blackfoot, it is 

 called Hell Gate River-; from there to the mouth of the Flathead it is called Missoula, 

 from there it retains the original name of Clark's Fork, though it is sometimes called 

 Columbia'. 



