162 Mr. R. Griffith on Mr. Weaver's Paper relative 



It is quite true that in the counties of Waterford, Cork and 

 Kerry, I have made considerable changes in the colouring of 

 my large geological map of Ireland, as compared with the 

 small one appended to the Second Report of the Irish Railway 

 Commissioners ; but I should observe that, at the period of 

 the publication of that map, and of the condensed Outline 

 of the Geology of Ireland which accompanied it, I enter- 

 tained doubts as to the accuracy of my views regarding the 

 true position in geological sequence of some of the arenaceous 

 and schistose strata of our southern districts. From the 

 Wernerian character of my geological education, I found it 

 almost impossible to conceive that quartz-rock and clayslate 

 could be newer than the old red sandstone, or even belong to 

 that series; and consequently when I found that the coarse 

 conglomerates of the counties of Tipperary and Waterford, 

 which rest unconformable on undoubted transition slate, alter- 

 nated with, and were succeeded in an ascending order by 

 red clayslate and red and gray quartz-rock, I was induced 

 to refer the whole series to the transition class ; but, judging 

 from their unconformable position in regard to the older clay- 

 slate, I considered them to belong to a newer transition series, 

 and described and coloured them as such. 



Soon after the publication of the Railway Report I made 

 a careful re-examination of our southern counties, and on 

 comparing the well-characterized old red sandstones of the 

 Slieve-naman and Galties mountains of the county of Tip- 

 perary, and of the Cahirconree or Slieve Meesh range of the 

 county of Kerry, with the conglomerate series of the county 

 of Waterford, I found them to be identical in geological posi- 

 tion, and to present no difference in mineral character beyond 

 a superior fineness in the grain of the upper members of the 

 red slate series which occur in the valleys of the rivers Black- 

 water and Lee in the counties of Waterford and Cork. Un- 

 der these circumstances it became evident that I should either 

 obliterate the old red sandstone from my map, and class the 

 whole with the transition series ; or assuming the unconform- 

 able position of the red conglomerate and slate with regard to 

 the older clayslates as an indication of a distinct period of 

 formation, arrange them with that series of rock to which 

 the name of old red sandstone has been given by British geo- 

 logists. 



In colouring the large geological map of Ireland, I adopted 

 the latter principle, and thereby removed the anomaly which 

 occurred in the small one, in which the conglomerate series 

 of the mountains of Clare, Tipperary, and the north of Kerry 

 were coloured as old red sandstone, while rocks occupying 



