Notices of Memoirs— Prof . E. Hull 457 



11. — On the Geology of the Environs of Dublin.^ By Prof. 



E. Hull, M.A., F.R.S. 

 TTIHE author remarked that the subject had been ably treated by 

 J_ the Rev. Maxwell Close, President of the Royal Geological Society 

 of Ireland, in the hand-book issued by the Local Committee of the 

 British Association. An excellent account of the same subject had 

 been given by Mr. Baily, and also in the very interesting publica- 

 tion called " Science Gossip." It had been the habit to begin the 

 meetings of the Section by giving a short description of the locality 

 in which the Section met, and in conformity with that custom he 

 would give a brief account of the geological structure of the 

 environs of Dublin. Before doing so, he might refer to the physical 

 features for the benefit of the strangers, who had honoured them 

 with their presence. The first feature that strikes the stranger 

 upon entering Dublin Bay is the beautiful range of hills, with their 

 several sharp or prominent peaks, lying to the southward. These 

 are the extremely northern points of the Dublin and Wicklow 

 mountains, which might be called the south-eastern highlands of 

 Ireland. They commence in the neighbourhood of Kingstown and 

 Killiney, and extend in nearly a southerly direction to Waterford, 

 a distance of about 40 miles, with an elevation at Lugnaquilla of 

 3039 feet. To the north and west of this range extends the great 

 central plain of Ireland, which stretches from the shores of the 

 Irish Sea, between Dublin and Dundalk, across the country towards 

 Galway Bay. It is bounded on the south of this range of hills, 

 which commences at the Devil's Bit, extending southwards towards 

 the county Limerick, crossing the Shannon above Limerick, and 

 going towards Clare and Galway ; thus forming the outworks of 

 the great south-western highlands, which includes the mountains 

 of Kerry, Cork, and Waterford. To the north there is another 

 range of hills of not so great an elevation, and then to the west are 

 the western highlands of Galway, Mayo, and Sligo, including the 

 beautifully picturesque tract of Connemara. All these hills are of 

 older formations than the central plain. They rise from beneath 

 that plain, throwing off the newer formations in every direction. 

 It is a curious geological paradox that the oldest formations 

 generally occupy the highest ground. As to the geological 

 structure, it might be better to take the order of deposition or 

 natural order of birth. The oldest formations in Ireland are repre- 

 sented in the neighbourhood of Dublin to the north and south of 

 the bay. This formation is called the Cambrian, similar to the 

 Lower Cambrian in North Wales. They consist of enormous thick- 

 nesses of reddish and green slates, grits, and quartzites traversed 

 by great fissures. These beds are very well laid open along the 

 railway cuttings at Bray Head, where some would have an oppor- 

 tunity of inspecting them on Saturday ; also at the Hill of Howth, 

 where the strata was of a precisely similar character. They were 

 characterized by very simple forms of animal life — Oldhamia of two 



iRead before the British Association for the Advancement of Science, Dublin, 

 (Section 0.), August 15, 1878. 



