104 PHYSICAL GEOGEAPHY. 



Sometimes the bluff-range, departing a little from the 

 general direct line, presents a full crescentic front to the plain 

 with an arc of several miles in length. Such, for example, 

 are seen at the town of Crescent, and again about seven miles 

 southward from Council Bluffs. At these places, their peculiar 

 outlines are shown in an interesting manner, and the form and 

 arrangement of the numerous rounded prominences present 

 views of impressive beauty as they stretch away in the dis- 

 tance or form bold curves in the line of hills ; while the broad 

 flood-plain of the Missouri river, level as a floor, stretches 

 miles away to the westward to meet the turbid stream near 

 the line of bluffs which borders the western, as those of Iowa 

 do the eastern side. Trees often fill the sides of their deeper 

 ravines or skirt their bases, but usually their only covering 

 is a growth of wild grasses and annual plants ; and, as the 

 mound-like peaks and rounded ridges jut above each other, 

 or diverge in various directions while they recede upward to 

 the upland, the setting sun throws strange and weird shad- 

 ows across them, producing a scene quite in keeping with 

 that wonderful history of the past of which they form a part. 



The accompanying sketch of a smaller one of these curves 

 in the line of hills known as Sergeant's bluff, is taken from a 

 point about two miles below Sioux City.* 



General Characters. Upon near approach to these bluffs, we 

 find that their peculiar features are due to the no less peculiar 

 character of the material of which they are composed, either 

 wholly or in part. When not wholly, that material which 

 differs from the great bulk appears only at the base and does 

 not modify their outlines. It is very distinct in character 

 from any other formation or deposit in the State; but is very 

 similar to that deposit in the valley of the Rhine, known 

 there by the provincial name of "loess." It was called 

 " silicious marl" by Dr. Owen, in his geological report to the 



*The plain between the two extremes of the crescentic line of hills as shown in the 

 picture is a part of the Missouri river flood-plain, and has some historic interest as the 

 death-place of Sergeant Floyd, a member of the famous Lewis and Clark Exploring 

 Expedition. 



