GEOLOGICAL SURVEY OF THE TERRITORIES. 



153 



About ten miles below the sta- 

 tion, on the right side of Bear 

 River, is Medicine Bow Butte, 

 which looms up conspicuously 

 above the surrounding country, 

 eight hundred to one thousand 

 feet above the bed of the stream. 

 It is undoubtedly composed, for 

 the most part, of strata belong- 

 ing to the coal series, which I am 

 disposed to regard as of tertiary 

 age. It is well grassed over, 

 and is covered here and there 

 wi'th dense groves of quaking 

 asp, &c. 



Passing along the stage road 

 westward from Bear Creek Sta- g 2 

 tion, over beds nearly horizon- §- 

 tal, or inclining at a small angle, § 

 we suddenly come to an up- % 

 thrust of rocks, called "The§. 

 Needles," which the traveler §■ 

 coming from the East for the g 

 first time will regard with aston- £, 

 ishment. Deep underneath an <j' 

 extensive covering of more re- q 

 cent deposits there seems to be If 

 an immense bed of coarse con- cj 

 glomerates, and at this locality, g- 

 by upheaval, these conglomer- ^ 

 ates havebeen thrust up th rough |. 

 the softer overlying beds in a * 

 nearly vertical position several | J 

 hundred feet above the road, g 

 and have been weathered by p 

 atmospheric influences into a 

 number of sharp conical peaks, 

 which have given to this land- 

 mark the name of "The Nee- 

 dles." It is made up of all kinds 

 of worn boulders and pebbles, 

 like those we see forming the 

 bed of any of our mountain 

 streams, varying in size from 

 that of a pea to a foot in diame- 

 ter. These rocks are held to- 

 gether somewhat loosely by a 

 kind of siliceous grit. Some of 

 the worn masses are themselves 

 an aggregate of worn pebbles, 

 proving that a portion of the 

 materials were derived from still 

 older conglomerates. Sometimes there is a thin local seam ot coarse 

 sand containing only a few pebbles, but the greater part of the entire 

 mass, five hundred to one thousand feet thick, is a coarse conglomerate. 

 It is situated near the Yellow Creek Station, and the ridge of upheaval 



