TOPOGRAPHY OF NEBRASKA. 15 



depression beyond the anticlinal ridge along which the Niobrara 

 flows. In the canyon region, in going to the Niobrara,when within 

 twelve or fifteen miles of it I invariably found myself going up 

 hill. It was rarely sensible to the eye, but the barometer noted it 

 distinctly. When the river was reached it lay from one hundred 

 and fifty to four hundred feet below. On the north side it was 

 again down' hill for a short distance. Some of the head waters of 

 the Loup originate close to the Niobrara, because of this ridge on 

 top of which it flows. This makes it impossible to drain much of 

 the country from the south. For the exceptional meteorological 

 conditions here the reader is referred to Chapter III. 



Sand Hills. 



South of the valley of the Niobrara and its canyons, and com- 

 mencing about longitude ioo° are the far famed Sand Hills. The 

 sands of these hills are partially moveable. Where they monopo- 

 lize the ground travel is difficult, both because of the inequalities of 

 the ground and their shifting character. They vary in height from 

 a few yards to several hundred feet. Their shape approximates 

 the conical form. A curious character of these hills is the conical 

 depression so frequently found on or near their summits which are 

 made by the winds. Many of these have the form of craters. 

 Sometimes these crater-like excavations occur on the sides of the 

 sand hills. Indeed almost every kind of wind sculpturing occurs 

 among them, and the observer is surprised at every step at the 

 strange forms that meet him. It is a fine field for the study of the 

 opposite effects on landscape of wind and water agencies. Such 

 crater-like holes freshly formed are destitute of vegetation. Form- 

 erly these "barren holes" were abundant in the sand hill regions. 

 Now the great body of them are grown over with grass, and new 

 ones in process of forming are only met with at longer intervals. 

 But by no means is so large an extent of country covered by them 

 as is sometimes represented. In going southward from the Nio- 

 brara after wandering among the sand hills for ten or fifteen miles 

 they are found often suddenly to cease, and a grass-covered prairie 

 of great richness to take their place. There are also extensive sand 

 hills at the head of the Loups. Between these sections there is 

 generally a gently rolling prairie with occasional sand hills dotted 

 over them. There are also sand hills south of the Platte from 

 Kearney eastward several miles in width, and on the upper Repub- 



