216 GEOLOGICAL SURVEY OF THE TEERITOEIES. 



the same north and south direction, notwithstanding the remarkable 

 and enormous flexure of the great dividing range of the Rocky Moun- 

 tains. Nor does this stop here; for if we cross the divide again and 

 enter the basin of Clark's Fork of the Columbia, we find the same 

 thing there on a reduced scale, the ridges which separate the southern 

 tributaries of the Hell Gate, with no considerable exception, following 

 the same rule. 



In consequence of this general direction of the minor ranges and 

 ridges, the smaller streams have generally a north or south course, 

 while the larger streams, to which they form tributaries, with one chief 

 exception, Green River, run eastward or westward. For example : Poav- 

 der, Tongue, and Big Horn Rivers ; Yellowstone and Missouri, above 

 their bends ; Clark's Fork of Yellowstone, Gallatin, Madison, Stinking 

 Water, and Beaverhead Rivers, on the Atlantic slope; and Deer Lodge 

 River, Flint and Stony Creeks, and Bitter- Root River, on the Pacific 

 slope, all run north ; while Green River, the upper part of Snake River, 

 and Henry's Fork run almost directly south. I might add to this list, 

 but these are sufficient to show that there is some great law which gov- 

 erns their direction, or that there is a remarkable uniformity. 



The direction and character of the mountains in the northwest part 

 of Montana are hereafter alluded to, and it is therefore unnecessary to 

 state them here. 



I have not visited the Salmon River Mountains, and therefore have 

 no very correct idea as to their character, but understand that they are 

 quite rugged and irregular. They give rise to but one important stream, 

 the Salmon River. And I may add here that an inspection of the best 

 maps of this but little- known section shows that here the same tendency 

 of the minor ranges to maintain the north and south direction prevails, 

 in consequence of which the upper portion of the river, and a number 

 of its tributaries, run north ; and Snake River, for two hundred miles of 

 its passage through this latitude, has the same direction. 



This is but an imperfect sketch of the mountain character of this 

 great elevated region, which, in many respects, presents more of the 

 oriental than of the occidental features. If we could stand at the extreme 

 southern end, and, looking north, take in at one view the entire reach 

 from the Missouri River to the Pacific Ocean, it would, between the 

 thirty-seventh and forty-fourth parallels of latitude, present the following 

 outlines : From the Missouri west, for four hundred miles,* we should 

 see an inclined plane gradually ascending from 900 feet at its eastern 

 limit, to 5,000, above the sea near its western extremity; slightly 

 curving upward, making the ascent a little more rapid in this part. 

 Here we would see a rugged wall shooting from 3,000 to 5,000 feet 

 higher, while west of it, for three hundred and fifty miles farther, 

 would be seen an irregular surface, slightly depressed in the middle, 

 but having a general level of 2,000 feet above the inclined plain east. 

 At the western border we should observe another rugged wall rising 

 one or two thousand feet, and descending, on its west flank, 2,000 feet 

 below the surface east of it. West from here we would observe the line 

 preserving this level for some distance, then curving upward somewhat 

 rapidly, until it reached an elevation of 6,500 feet above the sea, would 

 gradually descend a little below the line, immediately west of the last 

 wall. Here we should see another wall rising up to a height of 8,000 

 feet above the sea, from which the line, at first curving rapidly down- 

 ward, would descend to the level of the Pacific Ocean. 



* I limit these distances to direct measurement. 



