238 



ON THE GEOLOGY OF ANGLESEY. 



tation rather than that of Dr. Hicks, as the latter undervalued the 

 amount of metamorphisni the Anglesey rocks by the Menai Straits 

 had undergone. He differed from Prof. Ramsay as to the value 

 to be attached to the microscopic study of rocks ; he did not regard 

 the Bangor rocks as partially metamorphosed, and he fouud no 

 trace of the progressive metamorphism insisted on by Prof. Ramsay. 

 He defended the use of the term " granitoidite/' which, though 

 open to objections, was less misleading than the base-born term 

 proposed by Mr. Smyth. He thought that the microscopic study of 

 the rocks supported Dr. Callaway's conclusions. 



Dr. Callaway agreed with Prof. Ramsay as to the great value of 

 the Survey work. He contended that the principle of the identi- 

 fication of rocks by their mineral characters is a safe one when 

 applied in the same district. The sections described proved that the 

 .granitoidite was the summit of the gneissic series. Many of the 

 gneissose rocks were true gneiss of very typical character. The 

 difficulty through faulting was counteracted by comparing areas. 



