Revieivs—Prof. Kull's Physical Geology of Ireland. 167 



The Physical Geology and Geography of Ireland. By E. 

 Hull, M.A., F.E.S., Director of the Geological Survey, Ireland, 

 and Professor of Geology in the Eoyal College of Science, 

 Dublin. Post 8vo. with 2 coloured maps and 26 wood en- 

 gravings, pp. xvi. and 291. (London : Stanford, 1878.) 

 Second Notice. 

 (Continued from the March Number, p. 127.) 



HAVING thus given his readers an acquaintance with the funda- 

 mental structure, or, as it were, the internal anatomy of the 

 country, the author proceeds to discuss the causes of its present 

 features, its mountains and valleys, its rivers and lakes. And first 

 taking up the mountains, he naturally, as a geologist, devotes 

 attention principally to the question of the age of the mountain 

 ranges, that is, the date (geological) of their first birth, not merely 

 of their subsequent development or reproduction. It will be quite 

 unnecessary to explain here any of the steps in this reasoning, but 

 we shall give a summary of the conclusions which he arrives at. 

 The entire surface of Ireland, viewed as a whole, consists physically 

 of a great central plain bounded in most directions, but not entirely 

 surrounded, by groups of mountains. These naturally groujo them- 

 selves into (1) the N.W. Highlands; Donegal and Derry — (2) the 

 Western Highlands ; Galway, Mayo, etc. — (3) the S.W. High- 

 lands ; Kerry, Cork, with outlying ridges — (4) the S.E. Highlands ; 

 Wicklow, Dublin — and (5) the N.E. Highlands; Carlingford, Down, 

 etc. Of these the last mentioned are decidedly the most recent in 

 time of birth, they being decidedly later than the Carboniferous era ; 

 but older than Tertiary. The author believes them to be probably 

 Permian. They are old volcanic in origin. Then the S.W. High- 

 lands owe their existence to powerful terrestrial mechanical forces, 

 which have compressed the bedded rocks into enormous folds and 

 curves with a general E. and W. axial direction, their great anti- 

 clinals often broken and partly denuded at the top of curve, and 

 giving rise to some of the most elevated ground in Ireland, while 

 the synclinals have been eroded into river- vallej'S and deep fiords, 

 so well marked in the indentations of the S.W. coast (Bantry, 

 Dunmanus, Kenmare Bays). And these forces were brought into 

 action during the period between the Carboniferous and the Permian. 

 The other three groups, the western, the north-western, and the 

 south-western highlands, were of a date between the Lower and the 

 Upper Silurian (probably ' pre-Llandovery '), and are due to the 

 exertion of intense and widespread metamorphic action. The direc- 

 tion of the axes of these groups is nearly the same, and is between 

 E.N.E. and N.E. 



The ' great central plain ' next comes under review. This may 

 be roughl}'^ considered conterminous with the Carboniferous Lime- 

 stone, although this limestone itself is only occasionally visible, the 

 greater portion of the surface being covered by beds of Boulder-clay 



