124 '^^^^ Irish Naturalist. DcceiuocM-. 



REVIEWS. 



The Ice Age in the North. 



The Glaciation of North-eastern Ireland. By Major Arthur Richard 

 DwERRYHOUSE, T.D., D.S.O., M.R.I.A., F.G.S. Quart. Jouni. 

 Geol. Soc, Ixxix, part 3 (1923), pp. 352-422, plates xxiii-xxiv. 



This is a paper which should receive the careful attention of all students 

 interested in the study of the Pleistocene glaciation of Ireland. It deals 

 with the advances, retreats, and re-advances of the Scottish and Donegal 

 ice-sheets over a wide tract of country in north-eastern Ireland ; and 

 as it is, in Ireland, the first published study, on modern lines, of the 

 effects of glaciation on a large scale, it is most welcome. As the 

 publication of Major Dwerryhouse's work has been greatly delayed, its 

 belated appearance is the more to be appreciated, and it is to be hoped 

 that in the near future we may have the advantage also of knowing the 

 results of Prof. Charlesworth's investigations regarding the glaciation of 

 the north-west of Ireland, results which, we understand, have been ready 

 for publication for some years past. By combining the conclusions of 

 two specialists in Glacial phenomena, in these neighbouring areas, we 

 should obtain a comprehensive view of the succession of events during 

 the Ice Age in the North of Ireland. 



The region described by the author includes the counties of Antrim 

 and Down, with parts of Londonderry, Tyrone, Armagh, Monaghan, 

 and Louth, and this large area has been divided into what he considers 

 to be four natural geographical units^ — the basaltic plateau of Antrim, 

 the valley of Belfast, the Palaeozoic countr}^ of Down and Monaghan, 

 and the igneous districts of Mourne, Slieve Croob, and Carlingford. 

 Taking these areas in succession, the various Glacial deposits, and other 

 results of the advances and retreats of the ice-sheets, are dealt with, and 

 the boulder-clays, gravels and sands, and Glacial drainage channels are 

 described in such detail that only a few salient points can be mentioned. 

 In his work on the Glacial deposits of his district, whether boulder-clays 

 or gravels and sands, the author has one outstanding advantage, in that 

 there are many very definite rock-types which can be identified as occurrinii; 

 in situ in the Firth of Clyde. Among these may be mentioned the 

 riebeckite-eurite of Ailsa Craig, the granite of Goatfell, and the quartz- 

 porphyry of Drummadoon ; and the discovery of any of these in the 

 drifts to the southward is fair proof of the original northern origin of the 

 deposit in question. Where a suite of these northern rocks is found 

 any lingering doubt may be set aside. The author mentions a recent 

 discovery by Mr. Robert Bell of the Ailsa Craig eurite at Drumanewy some 

 miles west of Randalstown, and rocks of the same type have been found 

 as far south as Monaghan town. In the account of the Ballycastle 

 district the author gives an interesting description of the terminal 



