Correspondence — Mr. O. H Kinahan. 575 



Beds takes place somewhat rapidly, but this is noticeable all along 

 their south-easterly margin, and " conglomerates and coarse con- 

 glomeratic sandstones are notoriously local formations, suddenly 

 swelling out into great masses, and as rapidly dwindling down 

 again, or disappearing altogether," as Prof. Geikie remarks (Old Eed 

 Sandstone of Western Europe). I think also that the irregularity 

 of the surface presented by Pebble Beds to the succeeding forma- 

 tions, as well as their rather abrupt disappearance, ma}^ be accounted 

 for by the peculiarities of the deposit and of the position of the area 

 under consideration. 



The local occurrence of the Keuper Basement Beds at Nottingham 

 is, I believe, attributable to the same causes, and not to their having 

 suffered partial removal by denudation. As I remarked in my paper, 

 they have approximately the same distribution as the Bunter, and it 

 was not until the commencement of the Waterstone period, that the 

 old limits of the Bunter deposits began to be exceeded. For this 

 reason and others which I stated, I consider that the base of this 

 formation, conformable as it is to the underlying rocks, constitutes a 

 most important horizon in the Trias. A. Stkahan. 



Wrexham, Nov. 8th, 1881. 



DE. CALLAWAY AND THE WEXFORD LOWER PALEOZOIC ROCKS. 



SiK, — This writer in his paper on these Wexford rocks (Geol. 

 Mag. November, 1881) adopts the principle of the Archjean geolo- 

 gists, which I must again protest against, which is rushing to con- 

 clusions without a proper previous examination. In Donegal we 

 are now told that undoubtedly there are Laurentian rocks, while 

 in reality the question there has not been worked out since Jukes 

 first suggested they were Laurentian rocks ; and now Dr. Callaway 

 states my work is all wrong, without first seeing it. As stated by 

 him, anxious to arrive at the truth I pointed out all places where 

 anything was to be seen, and specially the sections that were most 

 important, and of the latter I specially called his attention to the 

 Crossfarnoge section, and those on the Saltee Island. To get to the 

 latter there may be a little trouble ; but in my course through life 

 I have always found nothing important can be done without some 

 trouble. Under present circumstances I could not answer Dr. 

 Callaway ; he does not know my work ; and until he does, it would 

 be unfair to expect he could understand it. Furthermore, before 

 he could understand Wexford, where so few rocks are exposed, he 

 would have to examine an area where they are better seen. There 

 could be no better field than Hiar-connaught, where, on account of 

 the absence of Drift, the rocks in places can be studied as if laid 

 down on a map. 



I am at a loss to understand where Dr. Callaway learned that 

 I have changed my opinion as to the age of the rocks north of the 

 Carboniferous trough south of Wexford town. Those rocks were 

 called Cambrians by Jukes, and a short time after I first saw them, 

 I found Oldhamia in them. That I am aware of, I published no 



