TRANSACTIONS OF SECTION C. 537 



5. The granite and felstone of the Eifel range, and some masses of felstone 

 to the north. 



6. The so-called ' altered Cambrian,' to the soutli of Glyn Clifon. 



7. The ridge of granite and the whole of the so-called altered Cambrian rocks 

 in Anglesea. 



In these areas it was found that the rocks resolved themselves into three very- 

 well-defined groups, and as the author had already recognised that these groups 

 formed part of three distinct formations at St. David's, unconformable on one 

 another, he proposed to divide the rocks of North Wales in the same manner. 



The lowest beds are like his Dimetian at St. David's, and consist chiefly of 

 granite or granitoid gneiss rocks. 



The next in ascending order is the great felsitic group, and for this he proposes 

 the name Arvonian* since it forms so large a part of the mountains in Caernarvon- 

 shire. 



The third includes most of the so-called altered Cambrian beds, and consists 

 chiefly of schists, or schistose rocks, and is usually a highly chloritic group. This 

 he associates with the Pebidian of St. David's. 



4. On " Gervus Megaceros." By William Williams. 



The " Cervus Megaceros," commonly called the " Irish Elk," whose remains often 

 occur in the marl beds under the peat bogs of Ireland, appears to have been drowned 

 by miring in the stiff clay forming the beds of lakes which were once very numerous 

 in the country, but which have since silted up, and are now occupied by peat bogs. 

 The author, having been engaged for ten weeks making excavations in search of 

 these remains in the Bog of Bally betagh, ten miles from Dublin, had arrived at the 

 following conclusions— 1st, that the animal had lived after the first glacial epoch, 

 as he found the remains resting on the lower boulder clay ; 2nd, that the clay in 

 which he found them seemed to indicate a temperate climate, as it was mostly com- 

 posed of vegetable matter, indicating very little degradation of mineral matter from 

 the surrounding hills ; 3rd, the clay last mentioned is covered with a bed three feet 

 thick, containing hardly any vegetable matter, it being almost all mineral. He 

 concludes that this bed of clay was produced by ice action degrading and wearing 

 down the hills. That it is glacial he infers — 



1. From its texture, it being ground granite. 



2. From its quantity ; an ordinary mild climate would not wear down the hills 

 to produce such a bed, and as it is at a level of 800 feet it has not been imported 

 from the drainage of other places. 



3. From having found a reindeer's antler in this bed, be infers that a sub-arctic 

 climate must have prevailed at time of its deposit. 



4. From the broken state in which the antlers are found, he cannot conceive 

 any force wbich would have been sufficient to break one of these beams of hard 

 sound bone three inches in diameter, unless the vertical pressure of immense masses 

 of ice, while the antlers were embedded in the lower clay ; running water could 

 not do it ; for the teeth have not their corners broken off, nor are the tracks of the 

 blood-vessels in the antlers ground off or water worn. 



Hence he infers that the animal lived after the deposit of the lower boulder 

 clay, and previous to that of the upper boulder clay, or that it lived inter-glacial 

 and may have been exterminated by the last ice period. 



5. On the Bodes of Ulster as a Source of Water- Supply. 

 By William A. Traill, M.A.I. , H.M. Geological Survey of Ireland. 



The author referred to the backward state of the study of hydro-geology in Ire- 

 land, and to the acknowledged necessity for larger and purer supplies of water for 



* From the Roman name Arvonia, and from which the present name of Carnarvon 

 is derived. 



