VALLEY OF THE MEDICINE BOW RIVER. 143 



Archaean gneisses between Rock and Elk Mountains, through which the 

 river cuts a narrow channel, trending in a nearly north and south direction, 

 until reaching the overlying sandstones, when it turns abruptly eastward, 

 following the line of junction between the two series of beds; the Fox Hill 

 strata appearing as a long line of prominent bluffs upon the north side 

 of the stream. To the eastward, where the overlying sandstones turn 

 toward the north, the river also runs in the same direction, but, before reach- 

 ing the railroad, makes a bend to the eastward, flowing through Colorado 

 Cretaceous strata. A short distance west of Medicine Bow Station, the 

 Colorado Cretaceous passes under the Fox Hill sandstone, and from here 

 the latter formation occupies the surface for at least 5 miles to the westward, 

 or to within 3 miles of Carbon. 



All the beds appear to dip westward, but with a varying angle, and 

 with a general strike of northwest and southeast, curving around somewhat 

 to a north and south course as we proceed westward. The surface presents 

 a gently rolling, barren country, with occasional edges of sharp sandstone 

 rising a few inches, or, at best, a few feet, above the plain, but sufficient to 

 indicate the position and inclination of the beds. Near the base of the series 

 occurs a prominent but low ridge of sandstone, which strikes north 60° 

 west, with a dip to the southwest of 32° to 37°. It consists of coarse, yel- 

 lowish strata, interstratified with beds of ferruginous clay-shales and black 

 carbonaceous clays, underlaid by deep-red ferruginous sandstones, passing 

 down into gray and steel-colored bed^. At the base on the west side of the 

 ridge are found two springs, highly charged with sulphur and salts of iron, 

 probably derived from the adjacent impure clay strata. Farther westward, 

 observed strikes gave north 40° to 45° west, and a dip of 25° to 30° west. 

 This ridge is followed by a broad, open country, without outcrops, and then 

 other ridges still dipping westward, but at lower angles ; the rocks present- 

 ing much the same general aspect. It was impossible to determine the 

 thickness of these beds, but there must be at least between 4,000 and 5,000 

 feet of strata represented. 



Carbon Basin. — The town of Carbon is situated directly on the line 

 of the Pacific Railroad, 656 miles west of Omaha, and 83 miles to the 

 westward of Laramie City. It lies 6,760 feet above sea-level, on a bleak, 



