TOPOGRAPHY OF CENTRAL WYOMING 



Valleys : None of the valleys calls for special attention 

 except that portion of the Platte Valley known as the Grand 

 Canon of the Platte. 



Here, unknown to most, is one of the masterpieces of canon 

 topography in America. Not only is the scenery of the highest 

 order, but the structural features revealed are of extreme 

 interest. Here, in magnificent vertical section, the whole range 

 of rocks, from the Archean up, can be studied in almost unbroken 

 series. In the region of the canon, the rocks dip quite uniformly 

 in a northerly direction. The river crosses the strike as a whole, 

 though it meanders more or less as it passes through the canon. 

 From a topographical point of view there are two especially 

 interesting points to be observed. First is the contrast of the 

 topography between the granite portion of the caiion and the 

 sedimentary rock portion. In the former case the river is nar- 

 row and confined between vertical walls of granite a thousand 

 or more feet high. The caiion resembles a \ertical cleft in the 

 ground, recalling in some of its features the well-known Canon 

 Diabolo of Arizona. On the other hand, as the river enters 

 the region of bedded rocks, the caiion takes on an entirely 

 different aspect; the walls recede from the stream in relatively 

 gentle slopes; the river itself has worn a broader channel; the 

 topography of the walls in this portion is also much more varied 

 than in the granite portion, since the elastics vary greatly among 

 themselves in regard to composition and character of bedding, 

 as well as in hardness. Here are brought out in great variety and 

 detail that common feature in canons, namely, the combination 

 of platform, cliff and talus slope. The topographic beauty of the 

 canon is greatly enhanced by the gorgeous colors of the rocks, 

 especially those of the Triassic, with their brilliant reds and 

 browns. The second noticeable feature is the meandering 



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