460 Notices of Memoirs — Dr. Henry Hicks. 



These shelly gravels only covered portions of a lower tract of 

 country in the neighbourhood of Dublin, and they ascend the flanks 

 of mountains to the height of 1100 or 1200 feet above the sea, 

 showing, he thought, that the land had subsided to that extent 

 beneath the sea, so that only the mountains of higher elevations 

 would rise above the level of the water and appear as islands. 

 There was another very remarkable formation, that of the Upper 

 Boulder-clay, which could be seen at Howth, and which succeeded 

 that to which he had alluded. There was only one other formation 

 to which he would refer, and that was the remarkable raised 

 beach which extended along the eastern coast from Wicklow to 

 the Giant's Causeway, round to Donegal. This raised beach was 

 represented by a terrace of shelly gravel belonging to the neigh- 

 bouring seas, and showed that the shore had been within a very 

 recent period elevated from 3 to 4 or 10 feet in the neighbourhood 

 of Dublin, and to a greater degree in the North. This beach was 

 shown by the Esplanade at Bray, which was really an old sea- 

 bottom raised five or ten feet above the original position. In the 

 North of Ireland the shelly beach was found to contain some of 

 those arrow-heads and flint instruments to which the President had 

 alluded. They would see from what he had said that they had 

 within a short compass a very considerable series of formations, and 

 he hoped the sketch he had given would enable geologists, and 

 those who took an interest in the subject, to better understand than 

 they otherwise would some points of interest in the geological 

 structure of the neighbourhood of Dublin. 



III. — On some New Pre-Cambrian Areas in Wales.^ By Henry 

 Hicks, M.D., F.G.S. 



DUEING some recent researches in Wales the author has been able to 

 add many new areas to the pre-Cambrian rocks already described. 

 In these examinations he has been assisted at different times by Prof. 

 Torrel, of Stockholm, Prof. McKenny Hughes, Mr. Tawney, F.G.S., 

 and Dr. Sterry Hunt, of Montreal. The additional areas to be now 

 added to those previously known are : — 



1. Some cupriferous schists with their associated greenstone bands 

 (the so-called intrusive greenstone of the Geological Survey) to the 

 north of Dolgelly, and including a great portion of Robel Tawr. 



2. Masses of granitoid rocks, porphyries, and greenstone breccias, 

 in the neighbourhood of Pwllheli. 



3. The porphyries and granitoid rocks forming Mynydd Mynytho, 

 and extending in a northerly direction towards Nevin, including 

 also Nevin mountain and the porphyries and greenstone breccias to 

 the north-east of Boduan. 



4. The Ehos Hirwain syenite and the so-called altered Cambrian 

 beds to the west of that mass in Caernarvonshire, and also Bardsey 

 Island. 



1 Absti-act of paper read before the British Association for the Advancement of 

 Science, Dublin (Section C), August 19, 1878. 



