540 THE MISSOURI RIVER. 



2679 miles further to the head of navigation at the 

 falls of the Missouri River, a short distance above 

 Fort Benton, or a total distance of 3905 miles. It 

 would have been better in such case to have called 

 the present Upper Mississippi, after passing the Mis- 

 souri, by some other name. In the first place, the 

 whole character of the Mississippi below that point is 

 governed by the Missouri, which at the junction of 

 the two rivers, is much the larger stream of the two, 

 the Missouri being a huge tawny flood of very muddy 

 water, while the Upper Mississippi is a clear water 

 river (which, by the bye, is a comparatively rare thing 

 in America, nearly all the rivers of any considerable 

 size being brown, turbid streams), but below the junc- 

 ture with the Missouri all the way to the sea it assumes 

 the Missouri colour, a deep yellow brown caused by 

 the friable banks, which all along the Mississippi-Missouri 

 system keep falling into the water, something in the 

 same way as we have already described, as charac- 

 teristic of the Lower Indus. 



Wherever there are high perpendicular clay banks 

 upon rivers, it may be assumed that the stream, espe- 

 cially in the concave portion of curves, is there eating 

 away its banks, their perpendicular character being 

 the result of such falls. The water mines them under- 

 neath, and soon the top cracks off and falls into the 

 stream; the loose material is then gradually washed 

 away by the river, in the form of sediment, which 

 causes the waters to be mud-coloured. With a slug- 

 gish stream the banks generally fall slowly, but when 

 there is a powerful and rapid current setting strongly 

 against a clay bank (especially if it be formed of 

 alluvial sands and mould) it is sure to fall more or 



