192 



The Irish Naturalist, October, 191 5. 



that island, and, as has been more than once surmised, it is extremely 

 probable that the Tree -Sparrow exists in many localities on our coasts, 

 but its presence has not been detected owing to its close resemblance to the 

 House -Sparrow. 



Nevin H. Foster. 



Hillsborough, Co. Down. 



REVIEW. 



GEOLOGY OF CENTRAL ULSTER. 



Explanatory Memoir to Sheet 58, illustrating parts of the Counties of 

 Armagh, Fermanagh and Monaghan (Second edition). By T. 

 Hallissy, B.A. With Petrographic Notes by G. A. J. Cole, F.G.S. 

 (Memoirs of the Geological Survey of Ireland). Pp. iv. + 26. 

 Map, I plate, and 2 text figures. Dublin : H.M.S.O., 1914. Price ■i^\d. 



The first edition of the Survey Memoir of the Monaghan area was pub- 

 lished in 1885, ^iid since then so much new information has been collected 

 in the district by the Survey that this second edition has become very 

 desirable. As regards the solid geology, the widely spread grits, slates, 

 and flags which were formerly vaguely classed as belonging to the Lower 

 Silurian of Wales have been re-examined and are now referred to the 

 Ordovician and Gothlandian, and correlated with the great series of rocks 

 of a similar type which stretch from Lough Gowna through Cavan and 

 Down to the Southern Uplands of Scotland. A considerable mass of 

 gabbro, discovered by Mr. R, Clark at Tanderagcebrack, to the southward 

 of Monaghan town, has been mapped, and a petrological description of this 

 interesting intrusion and of the other igneous rocks of the neighbourhood 

 is contributed by the Director of the Survey, Prof. G. A. J. Cole. 



The Boulder -clay of the district is of local origin, and as regards its 

 composition and erratics presents no features of special interest. The 

 great development of drumlins between Monaghan and Clones raised the 

 question of the origin of these long, low, smooth -backed ridges of Boulder - 

 clay, and Mr. Hallissy, the editor of this edition, gives a general account 

 of the theories advanced to explain their formation. That they are accu- 

 mulations of ground moraine may be assumed, but whether they are 

 the product of the advance of a single ice -sheet or are produced by the 

 erosion of earlier accumulations of the drift by the advance of a second 

 ice -sheet is still uncertain, and the examination of the Monaghan area 

 gives no fresh information on the question. A chapter is devoted to the 

 minerals of the locality, the Calliagh shales yielding iron and manganese, 

 while lodes of galena have been worked for lead in many places. The 

 memoir is illustrated by an excellent map in colours showing the new 

 divisions into Ordovician and Gothlandian ; it is a great pity, however, 

 that the photograph illustrating drumlins scenery should have been so 

 badly reproduced. 



J. de W. H. 



