Hayden.] 478 [Oct. 2, 1868. 



east side may be seen the snow covered ranges rising far above 

 all the rest, their summits touching the clouds. On the west 

 side there is also a short snowy range. The snowj- ranges on 

 the east border of the Pai'k have their north sides abrupt and 

 south sides less so as seen from a distance, as if the massive 

 rocky hills inclined southward. All along the north side of the 

 Park the lower hills incline south-westward, while the higher 

 ranges are quite steep, and correspond in the apparent dip of the 

 beds to the loft}'' snow clad mountains on the east which incline 

 south or south-westward. The inclination of the metamorphic 

 beds composing the higher ranges is from 60° to 80°. On the 

 west side of the Park long ridges seem to slope gradually down, 

 so that they die out in the plain, forming a sort of "en echelon" 

 arrangement. It is due to this fact that the area enclosed re- 

 ceives its oval shape. 



'The general trend of all the continuous mountain ranges is 

 nearl}' north-west and south-east on all sides, but there are many 

 local dips and variations from this direction. 



I was much interested to know whether any of the unchanged 

 rocks which are so well developed in the Laramie Plain occur in 

 the North Park. I found that the entire series of red and varie- 

 gated beds, including a portion of the Cretaceous strata, were 

 fully represented, all inclining from the flanks of the mountains, 

 and gradually assuming a horizontal position or nearly so 

 toward the central portion of the Park. The transition beds or 

 Lower Cretaceous, No. 1 (?), form quite conspicuous ridges incliu. 

 ing 19° to the south-west. They are composed of a very beau- 

 tiful pudding stone of small rounded pebbles, most of them flint, 

 cemented together with a siliceous paste. On the noi'th side are 

 quite large areas covered with loose sand which is blown about 

 by the wind, resembling the sand hills on the Niobrara River. 

 A close examination of the sand shows that it is composed 

 mostly of worn particles of quartz and feldspar. The surface 

 contains little or no vegetation presenting a peculiar barren 

 appearance, the sand moving readily with the wind. 



Hitherto it has been impossible to color on any geological 

 map the geological formation of au}^ part of this mountain re- 

 gion, and no information has ever been given in regard to the 

 structure of the North Park. It will be impossible even now, 

 with the imperfect topography of any of the maps, to color the 

 geology in detail, but these explorations will enable me to fix 

 the outline of the formation in a general way with a good de- 

 gree of accuracy. 



