THE SUPERFICIAL DEPOSITS OF NEBRASKA. 



By Samuel Aughey, Ph. D. 



The casual observer, passing over Nebraska, little suspects tbe mar- 

 velous histories treasured up in the rocks beneath his feet. These un- 

 derlying rocks represent four great divisions of geological history. Com- 

 mencing at the southeastern part of the State, and going westward 

 and northwestward, these divisions are, Upper Carboniferous, Per- 

 mian, Cretaceous, and Miocene and Pliocene Tertiary. The reader is 

 referred to the geological map found in Hayden's final Eeport on the 

 Geology of Nebraska, for the boundaries and extent of these deposits. 

 In Hayden's reports will also be found the descriptions of these deposits 

 and the story of the extraordinary life of past times which they unfold. 



The purpose of this paper is only to give some of the prominent fea- 

 tures of the surface geology of the State ; and, therefore, the older rocks 

 are only referred to in the case of the Miocene and Pliocene deposits, 

 where they constitute the surface in the bad lands in the northwestern 

 corner of the State. Nebraska, owes the peculiarity of its surface and 

 its great fertility mainly to three deposits, namely, the Drift, Loess, and 

 Alluvium. The poorer portions are principally produced by the sand- 

 hills, bad lands, and alkali lands. These deposits will be considered 

 in the order mentioned. 



THE DRIFT. 



The Drift is the most widely-diffused geological deposit in the State. 

 It constitutes the surface-soil in some places, but generally it is found 

 directly below the Loess. In rare instances it seems to have been re- 

 moved from the uplands by denudation before the Loess was formed. 

 Sometimes where it is exposed at the surface it is so mingled with the 

 Loess, Alluvium, and organic matter as to escape the attention of any 

 one save a practical geologist. It ranges in thickness from a few inches 

 to seventy-five feet. It may be much thicker, but if so I have seen no 

 exposures that indicate it. Nowhere does it come to the surface over 

 wide areas. In the northern part of the State it occasionally constitutes 

 the surface, in the southern part of Dixon County, in the northern part 

 of Wayne, and in portions of Cedar, Knox, Pierce, Antelope, and Holt 

 Counties. In townships 30 and 31 north, range 1 and 2 east, in Cedar 

 Couuty, semicircular rows of Drift pebbles and bowlders even yet extend 

 across narrow valleys, that lie on the flanks of high bluffs in the form of 

 terminal moraines of glaciers, the marks of which unnumbered 

 centuries have not been able to efface. In this region some of the gla- 

 cier-marked bowlders are of great size, weighing many tons. One of the 

 most remarkable lies near the quarter-section stone, between sections 

 25 and 36, in township 30 north, range 1 east. It lies on 

 top of the highest bluff in this region, from which there is a mag- 

 nificent view of the whole country around. It is a granitic quartzose 

 rock, about four feet square. On the level top-surface there is a beau- 

 tiful engraving of a child's foot, a half-moon, a grape-vine, and other 

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