AMERICAN 
JOURNAL OF SCIENCE AND ARTS. 
[THIRD SERIES.] 
> Arr. L.—Valley of the Minnesota River and of the Mississippi 
River to the junction of the Ohio: its origin considered; b 
Gen. G. K. WarREN, Major of Engineers. With Diagrams 
A, B, C, C’, D, E, F and G@ (making plates 11 to 18 of the 
volume). 
Definition of the term “valley,” prominent natural features and 
length.—The valley to be considered is the part included between 
the high banks, commonly called bluffs. Whenever it becomes 
necessary in this article to refer to the whole area drained by 
the river, the word basin will be used to designate it. 
Between these high banks the greater portion is subject to 
overflow at time of floods, forming what is sometimes called the 
flood plain; the smaller part above overflow is generally com- 
posed of alluvial terraces of sand and gravel. In some cases 
a Stele between the terraces and the bluffs is difficult 
oO make. 
these are natural landings for steamboats and sites for towns. 
course of time the convenience of the people living there 
makes them desirable locations for bridges. i is very rare, 
however, that both banks of the river are above submergence ; 
Where one bank is, the opposite one is generally low, and cov- 
ered many feet deep at extreme high-water, making it difficult 
to construct bridges sufficiently elevated for steamboats to pass 
under them. 
The distance along the general course of this valley from St. 
Louis to St. Paul is about 620 miles, but steamboatmen, by the 
course they take along the navigable channels, make the distance 
Am. Jour, Sct.—TuirD pas Vou. XVI, No, 96.—Dec., 1878. 
