12 The V\/esi American Scientist. 



excellent opportunity to study the physical character of tne 

 formation. 



The first thing', in all probability, that will attract the attention 

 of the unaccustomed observer will be the abrupt manner in which 

 the bluffs from the flood-plain of the river, which stretches without 

 undulation sometimes for four or five miles, I should judo^e, to the 

 westward from the foot of the bluff-chain. This feature is indeed 

 remarkable when we take into consideration that they contain 82^ 

 of silica, or sand. The angle at. which dry sand finds its repose 

 is less than 35 degrees, but here we can see walls composed 

 almost wholly of quartz sand rising to a great height and main- 

 taining an angle, which I measured at various places, at 65 

 degrees — so steep indeed that it is impossible for a human being 

 only ordinarily gifted to scale the slope. This high angle main- 

 tained is due to the presence of lime and iron which have, in the 

 course of time, partially cemented the sand grains together. This 

 angle of 65 degrees of which 1 have spoken is not universal, but 

 is quite frequently observed, more particularly near the summits 

 of the bluffs. 



This process of cementation has gone so far that the great angle 

 of inclination is not affected, or is affected but very slightly, by the 

 action ol rains or other similar agencies. In many places railroad 

 cuts have been made through the bluff material, and a perpendic- 

 ular wall will be left which will remain standing unaltered for 

 years. This feaiure is beautifully presented in the neighborhood 

 of St. Joseph, Mo., and to the southward. Wagon roads have 

 been cut through the material near Leavenworth and in Missouri, 

 just across the river, which have left perpendicular walls many 

 feet in height, and these have remained standing without a particle 

 of change that can be observed for many years, although the 

 material is light in character, ^and can be easily crumbled in the 

 hand. 



Another feature of the bluffs at Council Bluffs, and at other 

 places, more particularly in the northern part of the bluff-covered 

 area, is the absence of the luxurious timber growth wiiich almost 

 invariably characterizes our river valleys. In many places there 

 is a plentiful growth of scrub elm and oak a round the bases of 

 the bluffs, and here and there thick growths ol this dwarfed tim- 

 ber will be seen making a rush up the precipitous slopes, in a 

 manner suggestive of the attempts of a body of soldiery to scale 

 some disputed and coveted point, but only in rare instances has 

 the body succeeded in placing its banner on the top . • As we go 

 inland, or back from the river, and the prominent bluff character 

 is lost; we frequently find the entire face of the formation thickly 

 wooded; but where the bluff formation is most pronounced the 

 tops are always bare in the northerly regions — even the grasses 

 do not attain to the usual luxuriance, but everywhere the pale 

 buff colored bluff earth is visible, while just at the foot of the hills 



