GEOLOGICAL PAPERS. 123 



to by far the more i)iotiiresqiie features. It is exposed on White 

 Woman creek, in Greeley county, at Wild Horse corral, and at many 

 points along the Smoky Hill river. The Niobrara chalk has the 

 peculiarity of weathering with vertical walls where it is of homo- 

 geneous character, so that in many j)Iaces it has been eroded into 

 picturesque landmarks. Castle rock, in the valley of the Hackberry, 

 about ten miles from its mouth, is a lone pyramid composed of this 

 rock, and separated by a considerable interval from the main blutf . 

 Monument rocks, on the Smoky Hill river, are famous landmarks, 

 and formerly a stage station of the overland route was located at 

 them. Another picturesque group of rocks, which at a distance re- 

 sembles the ruins of many castles, is situated west of Elkader, in the 

 Smoky Hill valley. The Fort Pierre shales in Sherman county have 

 been eroded into a number of hills, which are capped with Tertiary 

 conglomerate. In traveling across the High plains one recognizes the 

 fact that they constitute the typical portion of the Great plains. The 

 following description is applicable to the High plains not only in 

 Kansas but in their extent beyond the limits of the state : 



The High plains, of unconsolidated material, above grade, and exposed to a 

 considerable precipitation, are held by their sod. . . . The great plateau 

 surfaces of the High plains have to show no systems of drainage, because, pre- 

 sumably, from the commencement of the present erosive stage, they have been 

 eod-covered, as at present. In other words, the High plains have endured as 

 alluvial plateaux since Tertiary times, or at least since the opening of the Pleis- 

 tocene. While degradation is at a standstill upon the plateau surfaces, the topo- 

 graphic belt which they constitute has, however, been appreciably narrowed 

 within a corresponding climatic belt by marginal recession. The limiting bluflf, 

 especially, that faces eastward, is carried backward by sapping on the part of 

 small streams or feeble beginnings of streams, originating in springs and " seeps" 

 at the bluff foot. . . . Agreeing generally in position with the topographic 

 subdivision of the High plains is also a subdivision by climatic difference. In 

 their westward rise of thousands of feet, the Great plains pass through climatic 

 gradations from humid to arid. . -. . (Johnson, 21st An. Rep. U. S. 

 Geol. Surv., pt. IV, pp. 610, 629.) 



