LITTLE OBDAR MOUNTAINS. 513 



range appears to be made up of beds of massive quartzite, occupying the 

 central portion of the mountains overlaid by dark-blue limestones, the latter 

 frequently appearing only in small patches on the flanks and ridges — frag- 

 ments left by erosion. The general trend of the strata is north and south. 

 Along the east flanks of the mountains, limestone is the prevailing forma- 

 tion, dipping at varying angles from 10° to 22°, passing under the Qua- 

 ternary valley, and apparently forming, with the west side of the Peoquop 

 Range, a synclinal fold. Here were found crinoidal columns and fragments 

 of bryozoans, together with 



Productus suhhorridus. 



In a very similar limestone on the west side of the mountains, but dip- 

 ping west at angles of 18° and 20°, were found the following Coal-Measure 

 forms: 



Productus Prattenianus. 



Athyris suhtilita. 



Syringopora multattenuata. 



CJiOitetes, sp. undet. 



, On the summit of the ridge just north of Albion Peak occurs a body 

 of highly-altered limestone, which, but for a small amount of fine quartz- 

 sand, has almost the theoretical composition of dolomite. It is a firm, com- 

 pact rock, of a bluish-gray color. 



Mr. B. E. Brewster, on subjecting it to chemical analysis, found the 

 following constituents : 



Silica 2.114 



Alumina and ferric oxide 0.274 



Lime 30.387 



Magnesia 20.069 



Carbonic acid. 45.726 



Water 1.708 



• 100.278 



33 D G 



