296 GEOLOGICAL SUEVEY OF THE TERRITOEIES. 



4G° 52',) is 1,393 feet above the sea, aud at the point where Mr. Slnn- 

 ner's line crossed it — about latitude 45° 28' — it is 1,207 feet above the 

 sea. This woukl give an average descent along this valley of a little 

 less than 1 foot to the mile. Missouri liiver, at Fort Union, has an ele- 

 vation of 1,970 feet; at the month of Heart River, 1,700 feet, and at 

 Fort Sully, 1,398 feet. Using these figures and calculating the distance 

 moved directly south, we find the descent to be about 2 feet to the mile, 

 or 140 feet to the degree of latitude. These figures would indicate that 

 the elevation of the river at Yankton is about 1,050 feet above the sea ; 

 but this estimate is probably a little too low, as the rate of descent 

 doubtless decreases as we move eastward and probably as we move 

 southward ; 1,130 feet would likely be nearer the correct figure. 



Another point in regard to the level of these leading streams worthy 

 of consideration is the difference between them at the same latitude. 

 At latitude 46° 50' the Missouri is 1,700 feet above the sea; the James, 

 1,393 ; and Red River, 900. At latitude 45° 30' the Missouri is (about) 

 1,510, while James River is but 1,260 ; yet the difference in longitude 

 between the two is about the same at this lower point that it was at 

 the upper, each having moved eastward, in this distance, about half a 

 degree. 



Passing west of the Missouri we have only to look at the map to learn 

 the direction of the descent, all the tributaries which flow into it below 

 the Little Missouri, as has before been stated, having an almost directly 

 eastern course ; but sufficient data have not been obtained to give the 

 vertical topography of this western section. 



If we enlarge our area, and include all north of Kansas River and 

 west of the Mississippi as far as the one hundred and first meridian, and 

 compare the elevations of points corresponding in longitude along the 

 different lines running west from the Mississippi, we will obtain a pretty 

 correct idea of the topography of the Northwest, as estimated from the 

 lower or water levels. It is true that this will not enable us to form any 

 idea of the higher intermediate points or the surface-contour, but know- 

 ing, as we do, that there are no elevated ridges, no prominent peaks or 

 rugged portions, the general slopes form the most important topograph- 

 ical feature. 



First. Along the line of the Northern Pacific Railroad, which corre- 

 sponds very nearly with the forty-seventh parallel of latitude : the Mis- 

 sissippi at Brainard, 1,205 ; Red River at Moorhead, 903 ; James River 

 at the crossing, 1,393 ; and the Missouri, at the mouth of Heart River, 

 1,700 feet above the level of the sea. 



Secondly. Along a line running from Saint Paul, by way of Lake Trav- 

 erse to Fort Sully, which, though bending considerably, we may consider 

 as corresponding with the forty fifth parallel of latitude: the Missis- 

 sippi at Saint Paul, CSO ; Lake Traverse, 900 ; James River, at the point 

 where Mr. Skinner crossed it, 1,200 ; Missouri River, at Fort Sully, 

 1,398. 



Thirdly. Along aline from Davenport, by way of Omaha and the Union 

 Pacific Railroad, corresponding very nearly with the forty-first parallel : 

 the Mississippi, at Davenport, 528 ; the Missouri, at Omaha, 966 ; Lone 

 Tree, on the line of the Union Pacific, 1,686 ; and North Platte Station, 

 on the same line, 2,789. 



Fourthly. On a line running from Saint Louis westward along the Kan- 

 sas Pacific Railroad, and corresponding with the thirty-ninth parallel: 

 the Mississippi, at Saint Louis, 375 ; State-line, at the mouth of Kansas 

 River, 648 ; Fort Harker, on the Kansas Pacific, 1,484 j and Buffalo, on 

 the same line, 2,678. 



