THE GREAT PLAINS OF COLORADO AND KANSAS. 



Ry S. F. Emmons. 



From Denver to Kansas City the entire width of the Great Plains is 

 again crossed, which present the same, or even greater, monotony of 

 scenery than where they were crossed on the outward journey in 

 Dakota. Their surface descends in a gentle but imperceptible slope 

 about 10 feet in the mile, or 5,000 feet (1,250 m.) in the 500 miles (800 

 km.) that lie between these points. There is but little variety of ero- 

 sional forms. The modern rivers, which in the spring and early sum- 

 mer are rapid, muddy torrents, constantly changing their meandering 

 courses in their wide bottoms, gradually decrease in volume during 

 the summer and autumn, and through the greater part of the year are 

 shallow, inconsiderable streams. There is evidence that the larger of 

 these streams have followed the same general course in early Tertiary 

 times that they do now, for Tertiary deposits have idled them up in 

 some places, and later erosion has not entirely removed these deposits 

 from the sides of the later channels. There is little to be seen of the 

 characteristically glacial topography shown on the more northern route, 

 nor are any typical mau rinses terres to be seen along the route of travel. 

 The streams whose valleys are traversed during the night and succeed- 

 ing day do not have their sources in the Rocky Mountains, as do the 

 Platte and Arkansas rivers, but head in springs between these two 

 rivers and at some distance from the mountains. 



The substructure of the Plains in this latitude is formed by strata of 

 Paleozoic, Mesozoic, and Tertiary ages, which lie nearly in position of 

 original deposition, and show no preceptible discordance of stratifica- 

 tion between the beds of successive series. The surface is masked to 

 some extent, especially along the more important valleys, by a loess-like 

 deposit which gives great fertility when rainfall is sufficient for culti- 

 vation, or when, as near the mountains, a sufficient supply of water may 

 be obtained for irrigation. In general, lower beds in the geological 

 series are disclosed in going east; but as the region has not yet been 

 systematically surveyed, except in limited areas, only the broader gen- 

 eral features of its geology are known. The transgression which is so 

 marked in the Appalachians between Paleozoic and Mesozic is not dis- 

 tinguished here. On the contrary, there seems to be a gradual passage, 

 not only in the sedimentation but in the succession of life, from the 

 Carboniferous into the Red Beds of the Trias. Between the latter and 



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