﻿590 



ME. J. Y. ELSDEN ON" THE IGNEOUS ROCKS [Aug. 1905, 



present. The agreement would have been still closer, if the alumina of 

 the Penmaenmawr rock had been diminished by the determination of 

 titanic and phosphoric acids, especially if allowance be made for the 

 water of hydration in the Penberry-Hill sample. The Carrock-Fell 

 hypersthene-gabbro has considerably less rhombic pyroxene, and 



lr 



•St 



I! 



s e 



•■s s 



« s 



S 



s 



bt) 



there is a corresponding deficiency in magnesia. The Whin-Sill 

 rock contains more iron and a smaller percentage of alkalies and 

 silica. 



On the whole, the composition of the Penberry-Hill rock seems 

 to entitle it to a place amoDg the quartz-norites, described by 



