GEOLOGICAL SURVEY OF THE TEREITOEIES. 265 



to one hundred and seventy-five miles, including the north part of Deer 

 Lodge, all of Ohoteau, and most of Meagher and Dawson Counties. 

 With the exception of the portions occupied by Belt, Highwood, and 

 Judith Mountains south of the Missouri, and by Bear's Paw and Little 

 Eocky Mountains north, it is generally an open, treeless plain, gradu- 

 ally descending eastward, with an average slope of 5 feet to the mile. 

 But this descent differs very materially in the portions east and west 

 of Fort Benton, that part west to the foot of the mountains having an , 

 average descent of from 12 to 15 feet to the mile, while that east has 

 an average of less than 3 feet, if the barometric measurements taken 

 along this line are to be relied upon. If this rate of descent east of 

 Fort Benton is correct, it lessens, to a considerable degree, the prospect 

 of redeeming any great portion of the plains, for it renders it impos- 

 sible to reach the higher table-lands with water from the Missouri. 



Along the east base of the Eocky Mountains, from the British pos- 

 sessions south to Sun Eiver, there is a strip of arable land, about thirty 

 miles in width, which is well watered by numerous little tributaries of 

 Marias, Teton, and Sun Elvers. The descent here being somewhat 

 rapid and these streams but a few miles apart, flowing in rather paral- 

 lel lines, a large portion of this strip, which is about one hundred miles 

 in length, can be irrigated and brought under cultivation. As it is yet 

 wholly unoccupied, except by roving Indian bands, consequently no ex- 

 periments in farming have been made, by which we mayj judge of its 

 climate ; but Mr. Hard, who has been traveling over this part of the 

 Territory, summer and winter, for some years, states that the seasons 

 are not severe, and that he is satisfied, from his knowledge of the cli- 

 mate, that the hardier cereals and vegetables can be raised without 

 difficulty from climatic influences. The grass is very good, and the 

 great buffalo herd of Eastern Montana, apparently fleeing before the 

 Sioux, has, during the present year, been moving over into this region. 

 The Marias Eiver, after it enters upon the plains, runs through a deep 

 channel, bordered, in part, by broad table-lands, and partly by long, 

 sloping hills, a part of which, by the construction of long ditches, may 

 be reached and irrigated and rendered suitable for agricultural pur- 

 poses. 



Teton Eiver is probably over one hundred miles long; its two 

 branches, rising in the Eocky Mountains west of the Teton, flow round 

 this hutte and unite at its east base. It has some good bottom-lands 

 in its valley, which varies from two to six miles in width for a part of 

 its length, but at other points is quite narrow. The bordering plains 

 are generally undulating, but a part is composed of level table-lands, 

 which are from 50 to 75 feet above the valley-level. The stream is 

 rather small, its average width being about twenty-five or thirty yards, 

 but it is a constant runner ; its lower portion runs slowly, the descent 

 being very slight. 



Sun Eiver, rising in the Eocky Mountains immediately west of Fort 

 Shaw, runs east about seventy-five miles, passing by this fort, and 

 empties into the Missouri. It forms the north boundary line of Lewis 

 and Clarke County. The immediate and cultivable valley of this river 

 varies in width from one to three miles, the soil being of the very, best 

 quality. There are terraces, at some points, flanking the bottoms, which 

 are of moderate height, and may be reached by irrigating ditches, in- 

 creasing the breadth of farming lands in this beautiful valley, which is 

 considered one of the finest in the eastern part of the Territory. The 

 stream is about sixty yards wide, flowing rather swiftly over a gravel 

 bedj seldom, if ever, overflowing its banks. There are, as yet, but few 



