Vol. 69.] PETROGRAPHY OF BARDSEV ISLAND. 533 



the south-west of the Lleyn. In that district the schistose struc- 

 ture, as emphasized by the Author, was very marked, and had 

 affected rocks of different kinds. The specimens laid on the table 

 from Bardsey Island could all be matched on the mainland. 

 Doubtless this crush-zone had an interesting bearing on larger 

 problems, as a previous speaker had pointed out. 



The President (Dr. A. Strahan) remarked that the production 

 of a map of Bardsey Island by the Author seemed likely to 

 coincide with that of a map of Anglesey by Mr. Greenly : the two' 

 were likely to be mutually helpful, for those islands had much in 

 common. 



He enquired whether it was not a fact that the late Dr. Hicks 

 had been the first to point out that the Irish-Sea ice had invaded 

 the coast of Wales, owing to the sea-basin having been filled to 

 overflowing, and that Dr. Jehu had confirmed this observation by 

 his work in Pembrokeshire. 



The Author thanked the President and Fellows for the kind 

 way in which they had received his paper. He was glad to have 

 the views of Mr. Barrow and Mr. Fearnsides on the nature and 

 •age of the earth-movements, although he himself had left the 

 discussion of these questions until, on the completion of the 

 mapping of the pre-Cambrian strip of the mainland, he would have 

 the full field-evidence before him. He agreed with Mr. Fearnsides 

 that soda-rocks occurred on the mainland, the sills intrusive into 

 the Arenig of the Aberdaron district being albite-diabases. 



To Dr. Elsden he replied that the post-movement dykes on the 

 mainland seemed to be identical with those of Bardsey, and, 

 although he had not yet examined any rock-slices of the former, 

 Tie expected that many of them would prove to be olivine- 

 dolerites. 



It was a pleasure to see a former worker in Bardsey present on 

 this occasion, and he paid a tribute to the value of Miss Baisin's 

 work in that island and on the mainland, especially with regard to 

 the igneous rocks. 



In regard to the glaciology, he was sorry to have over- 

 looked Mr. Fearnsides's record of a south-easterly ice-movement in 

 Merionethshire. Much more would have to be done before the 

 glaciation of South- Western Carnarvonshire could be regarded as 

 fully understood. He had looked upon Dr. Jehu's discovery of 

 boulders of Mourne-Mountain rocks in Pembrokeshire as evidence 

 of radiation of ice from Ireland into Cardigan Bay, but, in view of 

 Mr. Lamplugh's remarks, was now inclined to accept the latter's 

 opinion that they came from the bed of the Irish Sea and not from 

 Ireland itself. 



^sonian 



•U. J. G. S. No. 27' 



