TOPOGRAPHY OF CENTRAL WYOMING 



character of the stream, pointing to its superimposed origin. 

 The Tertiary rocks lie horizontally upon the inclined Paleo- 

 zoics and Mesozoics. The topography of the country indicates 

 that the river has been superimposed upon the earlier rocks 

 through the overlying Tertiaries. The unconformity indicates 

 this, the fact that the Tertiary rocks have been more extensively 

 eroded on one side than the other, and that, on the side in which 

 the monocline plunges toward the river, the erosive forces have 

 been much more active dovm the pitch of the plunging strata. 



The two points mentioned above are, perhaps, most notice- 

 able, though there are many others of interest. 



No attempt has been made in this bare outline of the topog- 

 raphy of southern Wyoming to give a scientific account of the 

 surface features of the region; its only object is to call attention 

 to some of its salient characteristics with the hope that it will 

 influence others to study in detail the features, which the mem- 

 bers of the Union Pacific expedition were enabled to study only 

 in the most hasty and imperfect way. 



GEORGE L. COLLIE. 



Referee in Topography, Logan Museum, 



Beloit, Wis. 



—61— 



