GEOLOGICAL SURVEY OF THE TERRITOEIES. 



255 



a distance of eighty miles. From Fort Owen, south, it varies in width 

 from four or five to fifteen miles, averaging some nine or ten; north 

 of this it is somewhat narrower, its average width not being* more 

 than five miles. It is all well adapted for agriculture, the soil being a 

 rich, dark loaiii, mingled with sand and gravel ; and where undisturbed 

 by the farmer's implements is covered with luxuriant grass, supplying 

 most excellent pasturage. In addition to the central stream, which is 

 of considerable size, there are a number of small creeks and brooklets 

 which flow into it mostly from the ridge to the east, of which the 

 following may be mentioned in the order they come, beginning at the 

 head of the valley : Weeping Child, Skarkahoe, Gird's, Willow, Burnt 

 Fork, Three-Mile, Six-Mile, and Bogues Creeks, all entering from the 

 east, and Nez Perces and Loulou Forks from the west. By proper 

 efforts this entire valley can be irrigated and brought under cultivation, 

 affording a rich agricultural area of at least four hundred thousand 

 acres. As its elevation is much less than the valleys which have been 

 mentioned as lying in the eastern part of the section, it has a much 

 milder climate. But the difference in elevation will scarcely suffice as 

 a sufficient explanation of the difference in climate between areas so 

 near to each other ; for here, especially from Fort Owen south, the val- 

 ley will be free from snow and the w^eather comparatively mild, while 

 other valleys, but a short distance north and of less altitude, are covered 

 with snow, and the temperature several degrees colder. And this is not 

 a mere accidental occurrence of one season, but so common as to have 

 been noticed by all who reside in or have remained in the valley for any 

 considerable length of time during the winter. This may ijossibly be 

 accounted for in this way: the general course of the winds in this 

 country, I believe, is from the northwest ; Clark's Fork (counting from 

 the head of Beer Lodge Creek to Lake Pend d'Oreille) forms a continuous 

 channel up which they may sweep in order to make their exit from the 

 section across the low gaps of the divide at the southeast corner. Bit- 

 ter-Eoot Valley being narrowed below and shielded on the west by 

 Bitter-Eoot Mountains, as a matter of course is much less liable to cold 

 winds and storms. In consequence of the direction of the leading 

 channel of this basin and the peculiar bends of the mountain-range 

 here, reasoning a priori we would be led to the conclusion that the 

 heaviest accumulations of snow would be found on the south side, in 

 the Big Hole or Wisdom Biver Basin, which I understand is the case, 

 though Mr. Stuart gives from the '^Backbone" down to the mouth of 

 the river on Big Hole as one of the areas of least snow during the winter 

 of 1861-'G2. 



The following statistics, though meager, will furnish some data by 

 which to judge of the climate of this valley : 



Altitude of Stevensville, a few miles south of Fort Owen, 3,412 feet 

 above the sea; of Fort Owen, 3,284; and of Missoula, near the junction 

 of Bitter-Eoot and Hell-Gate Elvers, about 3,000 feet. 



The mean temperature of the seasons and year at Fort Owen and 

 Stevensville, from the imjjerfect observations taken at these points, is as 

 follows: 



Spring. 



Summer. 



Autumn. 



Winter. 



Tear. 



Fort Owon . 

 stevensville 



48 

 47 



C9. 6 

 C9.G 



a:^. 6 



45.5 



24.9 

 27.6 



47 

 47.4 



