ALGHET.l NEBRASKA THE SAND-HILLS. 259 



more in the deeper pools and eddies which were rapidly filled up. The 

 species, so far as I have yet been able to determine, from an examina- 

 tion of the half-decayed wood, are the same as yet grow in this region. 

 They are principally cottouwood, elm, cedar, maple, and walnut. 



THE SAND-HILLS. 



The sand-hills are an often-mentioned portion of Nebraska. They 

 are found in certain sections of the western portion of the State. South 

 of the Platte Valley they run parallel with the river, and are from one- 

 half to six miles in breadth. A few are also found on the tributaries of 

 the Eepublican. Occasionally slightly sandy districts are found as far 

 east as the Elkhoru, but they rarely approach even a small hill in mag- 

 nitude. North of the Platte, from about the mouth of the Calamus on to 

 the Niobrara, they cover much larger areas. They are also found over a 

 limited area north of the Niobrara. Hayden (Eeport for 1870, p. 108) 

 estimates the area of the sand-hills at about 20,000 square miles. From 

 exploring the same region, I should not estimate them as so extensive, • 

 unless the fact be kept in mind that they are not continuous over the 

 whole region. They are indeed found all the way for 100 miles west 

 from the mouth of Eapid River, but in many places from eight to twenty 

 miles south of the Niobrara there are spots where the soil seemed to be 

 a mixture of Drift and Loess, and of high fertility, as was indicated by 

 the character and rankness of the vegetation- Sometimes these hills 

 are comparatively barren, and then again they are fertile enough to 

 sustain a scant covering of nutritious grasses; so that this region is by 

 no means the utterly barren waste that it is sometimes represented to 

 be. It has been a favorite range for buffalo, and still is for antelope 

 and deer ; and, judging from their condition, the conclusion would be 

 natural that this region could be used for stock-raising. A great deal 

 of the vegetation is peculiar to sandy districts. Some of the hills seem 

 to have their loose sands held together by the Ycea angustifolia^ which 

 sends its roots down to a great depth. It probably marks a certain 

 stage in their history. After this plant has compacted and given to the 

 sands organic matter, the grasses come in and partially clothe the hills. 

 The materials of these sand-hills are almost entirely sand, pebbles, and 

 gravel, of varying degrees of fineness. The sand always predominates. 

 Occasionally it is more or less modified by the presence of other mate- 

 rials, such as lime, potash, soda, alumina, and organic matter. These 

 hills are in some places stationary, and so covered by vegetation that 

 their true character is not suspected until closely examined. In other 

 places again, especially in portions of the Loup and the Niobrara region, 

 they are so loosely compacted that the wind is ever changing their form, 

 and turning them into all kinds of fantastic shapes. The most common 

 appearance is that of a plain, undulating, or hilly region, covered with 

 conical hills of drifting sands. The smaller elevations frequently show 

 striking resemblance to craters. One such curious hill I found south of 

 the Calamus, where the crater-like basin seemed to be compacted at 

 once, and grown over with a species of wire-grass. 



Some eminent geologists have sought to account for these hills by 

 the theory that the winds in the course of ages have blown the sand 

 from the bars on the rivers until their accumulation caused these pecu- 

 liar elevations. There are many difficulties in the way of this theory. 

 East of Columbus no sand-hills are found, and it is hard to conceive 

 how they should come to be limited to the western portion of the State 

 if they were formed in this way. In some places at least the hills are 



