THE MISSISSIPPI VALLEY. 



17 



mile. These streams are of about the same class, yet the descent of the former 

 is much the least rapid, as it ought to be, under the assumption that they both 

 descend along the slope of the great plane which reaches from the Alleghany to 

 the Ohio. The Licking crosses the plane obliquely, and descends it gradually ; 

 while the Big Sandy and the Guyandotte take a course at right angles to the 

 axis of the mountain ridge, and obtain, therefore, more nearly, the proper incli- 

 nation of the plane. 



The Great Kanawha, the next in succession, is a navigable river, and is cor- 

 rectly represented in the profile. From Loup Creek shoals to the mouth of 

 the river is 89 miles, and the descent 86 feet, or very nearly 12 inches per mile.* 

 The fall of the Ohio, from the mouth of the Kanawha to Cincinnati, is tW 

 inches per mile — in conformity with the rule. 



The Little Kanawha, from BuUtown to Ehzabethtown, lOSi miles, falls 181 

 feet; and from Ehzabethtown to the Ohio, 27^ miles, the fall is 28 feet, or 12| 

 inches per mile.f The descent of the Ohio below Marietta is GrW inches per 

 mile. 



The Scioto is not navigable. The distance from Columbus to Portsmouth 

 is about 100 miles by water, and the fall 302 feet. 



The Muskingum, from Zanesville to Marietta, about 60 miles, falls 104 feet. 



Wheeling Creek is a very small tributary, and, like other small tributaries, 

 has a rapid descent. From low water in the Ohio to the mouth of Wolf run, 

 a distance of 17 miles, the fall is 206 feet, or 12 feet per mile. 



The Alleghany river, as already shown, descends from Franklin to Pitts- 

 burg at the rate of 2 feet per mile ; while the Ohio, after receiving its great 

 tributary, flows off" with a fall of but little over 1 foot per mile. But the Monon- 

 gahela, the other great arm, contrary to the rule, and unlike every other tribu- 

 tary, has a descent more gentle even than that of the Ohio itself The fall of 

 this river, in the 91 miles extending from the Virginia State line to Pittsburg, is 

 75 feet, or 10 inches per mile. From Weston to the State line, a distance of 

 107 miles, the fall is 223 feet, or a fraction over 2 feet per mile. 



A reference to the map, with constant regard to the fact that there is a con- 

 tinuous though irregular plane, reaching from the Ohio to the summit of the 

 Alleghany mountains, will account for this anomaly. 



The course of the Monongahela, from its source to its confluence with the 

 Alleghany, is almost due north ; and consequently, in ascending from its mouth 

 to its source, we double upon the course of the Ohio, keeping a direction 

 parallel with that river, and also with the axis of the great dividing I'idge. But 

 the Ohio, which marks the foot of the plane, and the summit of the Alleghany, 

 which marks its upper edge, both have a dip to the south ; and the Mononga- 

 hela, running due north, is therefore surmounting the dip while its surface is 

 descending to the Ohio. 



• Surveys of Charles Ellet, Jr. 



t Survey of C. Crozet, Esq. , 



