112 PHYSICAL GEOGBAPHY. 



streams is greater than it is elsewhere in the State. This 

 is well shown in the profiles which illustrates the topography 

 of the State opposite a previous page, and has made railroad 

 building a difficult matter in some parts of western Iowa. 

 This difficulty has usually been avoided by running the roads 

 down some one of the smaller valleys to reach that of the 

 Missouri river. 



The banks and beds of the streams which traverse this 

 deposit receive from it quite peculiar characters. The beds 

 are of soft, fine, dark-colored homogeneous mud, and the 

 banks are composed of the same material in a dryer con- 

 dition. The banks are often, even upon the small streams, 

 from five to ten feet or more in height, quite perpendicular, 

 so that they make the streams almost everywhere unfordable, 

 rendering them in consequence a great impediment to travel 

 across the open country, where there are no bridges. 



The value of the material of this deposit as soil will be dis- 

 cussed further on, but it may be remarked here that it is 

 unsurpassed by any soil in Iowa for real value. It is true, 

 also, that forest trees grow as triftily upon it as upon any 

 other soil, even where there is no other kind of soil within 

 many miles of them, nor within a hundred feet beneath their 

 deepest rootlets. A thrifty growth of young forest trees 

 is now spontaneously springing up everywhere upon this 

 deposit, and rapidly encroaching npon its hill-sides and 

 prairies whenever they are by any means protected from the 

 annual prairie fires. This is at present more apparent upon 

 the hill-sides than npon the flatter prairies, and as one passes 

 along the road which traverses the length of the Missouri 

 river flood-plain, in view of the ever-varying and ever- 

 interesting bluffs, he can hardly avoid a feeling of regret 

 that the primitive beauty of their nakedness is so soon to 

 receive a forest-mantle of nature's own weaving, by which 

 their graceful outlines, now cut so clearly against the sky, are 

 to be forever lost; so rapidly are the hitherto fire-stunted 

 trees assuming forest proportions and multiplying their 

 number. 



