PlSfON RANGE. 

 The following ideal section was made by Mr. Walcott: 



201 



fcF^ 

 fc-^ 



J^tmestone-. 



JEiiretta. 



limestone. "Limestone. 



fv\. 4. Section across Pinon Range. 



Carboniferous 



Across the range from west to east along the line of the section a dark 

 blue limestone, carrying a few fossils of the Lower Devonian, rises above 

 the plain. Beyond the limestone a sharp oblique fault brings up a broad 

 mass of quartzite, conglomerates, and black siliceous pebbles. These, in 

 turn, are conformably underlain by blue limestone, from which a sufficient 

 fauna was secured to identify Upper Devonian beds. The limestones are 

 again cut off by a profound fault, apparently along a line of an anticlinal 

 axis. To the west of this fault the beds all dip westward, but beyond this 

 point present an easterly dip, at least as far as the base of Pinto Peak. 

 Directly eastward of the fault a dark ferruginous quartzite stands out 

 prominently, followed by light gray siliceous limestones, the age of which 

 is determined by the presence of Halysites. The beds gradually assume the 

 habit of the Devonian and carry a fauna sufficiently characteristic to estab- 

 lish the horizon of the Lower Devonian, and still higher up in the series 

 yielded Upper Devonian species. Overlying the limestones occurs a great 

 thickness of quartzites and sandstones, with occasional argillaceous bed. 

 Near the junction of the Devonian limestones with the overlying quartzites 

 the beds upon both sides of the anticline are identical, showing the corre- 

 sponding horizons without the evidence of the fauna. If the White Pine 

 shale of Eureka is at all represented in the Pinon Range it is found in the 

 argillaceous and finely siliceous beds immediately overlying the Devonian 

 limestones on both sides of the fault. These beds resemble those observed 

 at the same horizon at The Gate, already described, and the continuance 

 northward of similar sediments is not without interest, especially when 

 taken in connection with the great thickness of White Pine shale to the 

 southeast as developed in the Diamond Range, Cliff Hills and White Pine. 



