Vol. 50.] ANNIVERSARY ADDRESS OF THE PRESIDENT. 135 



be contradicted by the next. It is interesting to bear in mind 

 certain points of resemblance between tbe Lizard district and the 

 North-west Highlands indicated by Mr. Teall, more especially as 

 regards foliated crystalline rocks being cut by basic dykes, which 

 themselves pass into schists. So far as it goes, this evidence is in 

 favour of the generally accepted view that the Lizard rocks are of 

 Archaean age. "Whether the whole mass segregated from a homo- 

 geneous magma as held by Mr. Somervail, 1 or whether the relations 

 of the several rock-masses are those of intrusion, is perhaps a 

 question which cannot be very easily answered. Should the former 

 view be the correct one, in that case, according to the accepted 

 determination of the order of crystallization, which we have seen 

 applied by Messrs. Dakyns and Teall, and quite lately by Prof. 

 Brogger, the now serpentinized peridotite must have been the earliest 

 rock to consolidate. 



Britanny and the Channel Islands. — A study of the older rocks of 

 this region may be expected to throw some light on the problems 

 suggested by the Lizard, and for this reason I venture to cross the 

 English Channel. The principal authors in this field have been 

 Prof. Bonney and the Rev. Edwin Hill. It is now nearly eight 

 years since the excursion of the Geological Society of France 

 to Britanny drew the attention of geologists to that peninsula. 

 Dr. Charles Barrois, of Lille, prepared on that occasion an excellent 

 summary of the geological constitution of Einistere for the use 

 of the excursionists, amongst whom was Mr. Hill. Prof. Bonney 

 acknowledges his obligations to both these gentlemen in the 

 preparation of his notes on the structure and relations of some 

 of the older rocks of Britanny. He expressly says that he did 

 not go there to criticize but to compare, and to ascertain the bearing 

 of the rocks of Britanny upon general questions of metamorphism and 

 the genesis of crystalline schists. He noticed certain glaucophane- 

 amphibolites and associated schists, which he considered as undoubt- 

 edly of igneous origin, but subsequently modified by pressure. 

 The banded gneiss at the embouchure of the Pouldu and at Roscoft', 

 especially the latter, constantly reminded him of the more typical 

 members of the ' granulitic ' series at the Lizard, the structures of 

 which are very difficult to explain on any theory of a ' rolling-out ' 

 of a complicated association of igneous rocks. At that time he 

 concluded that, while the structures of some foliated rocks may be 



' Geol. Mag. 1892, p. 364. 



