LARAMIE PLAINS. 79 



the steeper slopes. All the beds fall away gently, with an occasional ridge 

 formed by a layer of hard sandstone, capping softer beds, which presents a 

 slight escarpment toward the mountain, and through which the streams 

 have cut their channels, exposing portions of the strata. On Antelope 

 Creek, the gypsum deposits are well shown, just north of the Willow Creek 

 and North Park Koad, interstratified in dark red sandstone. South of the 

 road, about one mile, bordering the creek on both sides, the light-colored 

 Triassic strata have been eroded into the most fantastic and fanciful forms, 

 which very readily suggest the name, which has been applied to them, of 

 the ■" Ruined City". They are neither as prominent, nor cover so large an 

 area, as the similar formation at Red Buttes, but, on the other hand, are much 

 more compact, with great diversity of outline, and suggest a variety of 

 architectural designs. 



A short distance west of Antelope Creek, the Triassic rocks occupy a 

 re-entering angle, or depression, in the Archaean body, extending some 

 twelve miles to the southward of the Colorado and Wyoming boundary, and 

 westward to the Laramie River. Along the east side of the river is a nar- 

 row strip of Archaean rocks, upon which the Triassic beds rest. Here the 

 Red Beds, and probably the overlying Jurassic marls and limestones, are 

 well developed, exhibiting a series of nearly horizontal strata, between 1,000 

 and 1,200 feet in thickness, with perhaps a very slight inclination toward 

 the north and northwest, the beds dipping away from the Archaean body. 

 Facing the plains, the red sandstone presents an abrupt wall from 600 to 

 1,000 feet in height, showing in a marked manner the variegated beds, with 

 the interstratified marls and limestones ; while, on the east side, Sand Creek, 

 which rises on the top of the plateau, cuts a deep, narrow canon through 

 the Red-Bed formation. These exposures exhibit a development of Triassic 

 beds at least 1,000 feet in thickness, and are overlaid by the light-colored 

 Jurassic strata, forming the summit of the plateau. 



Resting upon the Archaean body, the lowest beds consist of coarse, fri- 

 able, ash-colored sandstone, with pebbles and angular fragments, over- 

 laid by a thin bed of hard, cherty limestone, which is, in turn, overlaid by 

 reddish-gray sandstone. Above this comes the usual persistent red sand- 

 stone, passing up into clayey beds, more or less shaly, developing into a 



