50 PROF. T. a BONNET ON THE [Feb. 1 896, 



Speaking as to tbe origin of hornblende-schists, he reaffirmed his 

 belief in the theory that both gabbros and basic dykes had been 

 converted into rocks of this character by dynamic metamorphism. 

 He pointed out that in 1887 he had called attention to the existence 

 of a zone of intense mechanical disturbance in the south-western 

 portion of the Lizard, and to the fact that this had been accepted by 

 the Author. The main mass of hornblende-schist lay to the east of 

 this zone : in the same position relative to a zone of disturbance as 

 the Moine Schists of Sutherland. There was a close resemblance in 

 structural features between the main mass of hornblende-schist and 

 the Moine Schist, and he thought it highly probable that this 

 resemblance would be found to be due to dynamic metamorphism. 



The Eev. Edwin Hill said that Messrs. Fox and Teall seemed to 

 imply that granulite had been thrust into serpentine at the Lion 

 Rock, but it appeared to him that the opposite was the case. At 

 Potstone Point he saw no such folding as they seemed to speak of. 

 As for the fact that the bands of included masses of granulite 

 usually follow the external boundaries of the masses, it was most 

 natural to expect that the masses when ripped should yield along 

 the banding as lines of least resistance. 



Gen. McMahon said that, if he understood the Author aright, 

 the latter now believed that no part of the hornblende-schists had 

 originally been ash-beds ; if so, he reserved his judgment on that 

 point. In all other respects he was in cordial agreement with the 

 Author. He had not visited the whole area covered by Messrs. Teall 

 and Fox's paper alluded to, and could only speak to the parts of the 

 Lizard actually visited by him. He thought that there had been 

 granitic eruptions at different periods in the Lizard area, and that the 

 intrusion of the granite which had been injected into what is known 

 as the granulitic series was of earlier date than the granite which 

 had invaded the serpentine. As regards the question of the intrusion 

 of the serpentine into the schists, and the granulitic series, his mind 

 was at rest. He had seen several sections which had convinced him as 

 to the correctness of Prof. Bonney's original discovery of the relations 

 of these rocks ; and he mentioned, in particular, the section to be 

 seen in the Flagstaff Quarry, Cadgwith, which could not be explained 

 on the hypothesis of the serpentine being caught up in the folds of 

 the granulitic beds. 



Sir Archibald Gelkie said that he had had the advantage of 

 being conducted over part of the Lizard district by Mr. Fox and 

 Mr. Teall, and though he would not venture to offer an opinion upon 

 most of the disputed questions in the geological structure of that 

 area, he had seen evidence sufficient to convince him that in the 

 Potstone Point part of the coast the serpentine and hornblende- 

 schist formed, as Mr. Teall maintained, a great complex which 

 presented a marked coincidence of banding and had been plicated by 

 one common series of movements. He could see no indication of 

 the serpentine being intrusive in the schists. Without expressing 

 any judgment as to their relative date or mode of origin, he could 

 not doubt that both groups of rock had been simultaneously exposed 



