Geological Society, 45 



In the communication explanatory of these coloured maps, i hope 

 to prove that the old red sandstone, with few exceptions, passes 

 down into, and is conformable to, those rocks, to which we have been 

 accustomed to apply the term "Transition j" and that, throughout great 

 areas, the old red sandstone is equally conformable to the overlying 

 carboniferous limestone as to the underlying grauwacke ; — that the 

 fossiliferous grauwacke is divided into a number of large natural for- 

 mations or groups, charged with a variety of organic remains, for the 

 most pari undescribed. In tracing the lines of disturbance which 

 have affected these deposits, flexures upon a gigantic scale will be 

 pointed out, whereby the old red sandstone has been thrown into 

 basins of elevation, and, by a reversed inclination, extended to the 

 westward, far within the escarpment of the grauwacke ; and these lines 

 of disturbance and elevation will then be delineated, and their re- 

 lation traced to ridges of intrusive rocks. 



Whatever merit these observations may possess, they cannot but 

 derive value from being linked with the contemporaneous investigations 

 of Professor Sedgwick, amid the adjoining regions of grauwacke, 

 slate, and older rocks of the Welsh mountains. 



This will become evident when the Professor shall exhibit to you 

 the directions of those extensive anticlinal and synclinal lines which 

 he has determined with much personal labour, though unaided by 

 good geographical data. It will then be shown by him at what pe- 

 riods igneous action has been in operation within these older rocks ; 

 whilst it will be my province to point out how these outbursts have 

 been succeeded, on the eastern frontiers of the principality, by other 

 linear, submarine eruptions, and to describe the effects produced by 

 them upon the different sedimentary strata. 



These results must, however, only be viewed as the first attempts, 

 on the part of Professor Sedgwick and myself, to reduce to chrono- 

 logical order a vast succession of ancient deposits, which have hitherto 

 been much neglected in this country, on account, as we may suppose, 

 of the alleged obscurity of their organic remains, and still more, per- 

 haps, in consequence of their altered condition, due to the numerous 

 convulsions to which they have been subjected. 



Ireland. — We have been favoured with two communications upon 

 the geological structure of parts of the North of Ireland, illustrated by 

 excellent maps, constructed by the authors. In one of these, Mr. A. 

 Bryce, of Belfast, describes the north-eastern portion of Antrim, in 

 which he points out a much larger extent of mica schist than had 

 been noticed by former observers. These primary rocks are succeeded, 

 in ascending order, by ancient red conglomerates, partial carbonife- 

 rous deposits, new red sandstone, lias, greensand, and chalk. He 

 mentions porphyry as only associated with the older red sandstone; 

 and basalt, as overlying the chalk, all the important peculiarities of 

 which have been so well detailed by Conybeare and Buckland. 



The other Memoir upon Ireland is from the pen of Archdeacon 

 Verschoyle, and is much more comprehensive, describing the north- 

 west coast of Mayo and Sligo. The accompanying map is of consi- 

 derable value, the geographical features having been obtained from 



