530 DESCRIPTIVE GEOLOGY. 



Thence to the top of the series Hmestone occupies the whole body, and here 

 makes an exposure above the quartzite of not less than 6,000 feet. 



In this great thickness of limestone occur beds exhibiting considerable 

 variety in texture and composition. In the lower part of the series, thin 

 calcareous shales, more or less arenaceous, are a characteristic occurrence, 

 while higher up more compact beds of argillaceous material are found inter- 

 stratified in the limestone. Near the summit of the ridge, beds of highly 

 metamorphosed dolomites occur, of a bluish- white color. 



Not far from one of the dolomitic zones, a bed of nearly white, sacchar- 

 oidal limestone was observed,, altered into a coarse marble. It has been 

 analyzed by Mr. B. E. Brewster, with the following result : 



Alumina and ferric oxide 0.363 



Lime 54.513 



Magnesia 0.273 



Soda trace 



Carbonic acid 43.1 30 



Phosphoric acid 0.349 



Water 0.109 



Insoluble residue 1.347 



100.084 



Carbonate of lime 97.345 



Carbonate of magnesia 0.573 



97.918 



Fragments of Coal-Measure fossils may be found scattered through the 

 higher members of the series, but so far the lower members have yielded 

 none. Stems of cyathophylloid corals, Bellerophon sections, and poorly- 

 preserved forms of Spirifer are abundant ; but the only species obtained 

 that could be identified were : 



CJionetes granulifera. 

 Productus Nehrascensis. 

 Fusilina cylindrica. 



