kmmhns.] LEADVILLE TO MANITOTJ. 425 



the northeast. The Cambrian quartzite is not distinctly recognized. 



The Silurian is represented by grayish limestones, the Lower Carbonif- 

 erous by dark blue or gray limestones. Above these come a series of 

 black shales and impure limestones, belonging to the Middle Carbonif- 

 erous, followed by a great thickness of purplish-red beds, sandstones, 

 conglomerates, and shales, which constitute the Middle and Upper Car- 

 boniferous, a horizon whose lithological constitution varies much in the 

 Pocky Mountain region. As yet only plant remains have been obtained 

 from these beds. Their apparent thickness is magnified by a secondary 

 roll, and probably by some faults. Still above them arc the liner- 

 grained, bright-red sandstones which here constitute the Red Beds of 

 probable Triassic age. 



At Badger station the valley widens, and rocks in the immediate 

 vicinity of the road are obscured by Pleistocene gravels. 



From Howard station a Hue view is obtained, through the hills to 

 the southwest, of the peaks of the Sangre de Cristo range, which 

 forms the southern continuation of the Sa watch and Mosquito uplifts, 

 though not in a direct line with either. 



Beyond Vallie station the road leaves the open valley and passes 

 into a gorge of Archean, on the west flanks of which rest thin-bedded 

 limestones dipping westward. The Archean rocks consist mainly of 

 dark gneisses and amphibolites, with intrusive red granite, showing 

 considerable regularity of structure. 



From Cotopaxi station a stage line runs south into the Wet Moun- 

 tain valley, a great interior depression to the southward between the 

 Sangre de Cristo range on the west and the Wet mountains (which 

 face the Great Plains) on the east, in which is the Silver Cliff mining 

 district. 70 



The road now passes for several miles through a peculiarly crumbling, 

 massive red granite, which is found in most of the deep cuts across the 

 Archean mass of the Rocky Mountains, and is apparently a lower por- 

 tion of the Archean series. 



Texas Creek, the next station, is at the mouth of a stream of that 

 name which drains the northwestern portion of the Wet Mountain val- 

 ley. The Arkansas valley here opens out in the crumbling red granite, 

 but narrows again a few miles to the eastward, passing into granite- 

 gneiss, with an apparent bedded structure dipping to the eastward. 

 It contains large pegmatite veins and a considerable development of 

 amphibolite schists. The road then passes into another small open 

 valley above Echo station, from which, looking up the northern tribu- 

 tary valleys, can be distinguished hills capped by dark lavas. 



Beyond Echo the road passes again into a winding gorge of granite- 

 gneiss, whose structure lines dip 50° to the east. Through this are 

 intrusive masses of coarse grey granite and pegmatite veins. 



