G. H. Kinahan — Irish Metamorphic Rocks. 9 



assemblage appears to be the north-easterly extension of the rocks 

 of West Galway ; elsewhere I have suggested that they are probably 

 either metamorphosed Ordovicians or Upper Cambrians. 



Charlestown District. — This small exposure occurs near the north- 

 east boundary of Mayo ; the rocks are more or less similar to those 

 in Tirhugh, but so few of them are exposed that it is difficult to 

 form an opinion as to their age ; for the reasons given in a paper 

 read before the Royal Irish Academy, I have suggested that thej 7 may 

 be either of Upper Cambrian or Ordovician age, probably the latter. 

 As yet they have not been claimed as Laurentians. 



Slieve Gallion or Pomeroy District. — This area is principally in 

 the Co. Tyrone, only a small portion extending into the Co. Derry. 

 The opinions in regard to the age of the rocks have undergone 

 sudden and extraordinary changes. First, they were mapped as 

 of Lower Silurian age, and when I showed that this classification 

 must be incorrect, it was again insisted on ; but subsequently this 

 opinion was suddenly ignored, and they were stated to be of Laurentian 

 age. Lithologically many of these rocks are very similar to some of 

 the Canadian Huronians, and if there are any Archaean rocks in 

 Ireland, they probably occur here, as the rocks are evidently much 

 more ancient than the Ordovician to the south, while they appear 

 to be older than the submetamorphic rocks to the northward in the 

 Co. Derry ; however, for reasons given elsewhere, I suspect that 

 they are metamorphosed Cambrians. 



Gary or Ballycastle District. — These rocks occupy a tract at the 

 extreme north-east of Ireland, in the Co. Antrim. They seem to be 

 the north-east extension of the Slievegallion rocks, and to be of a 

 similar age, having been heaved northward by the great faults of 

 the Lough Neagh basin. As yet they appear to have escaped the 

 general confiscation. 



Tar- Connaught or West Galway. — This tract lies immediately north 

 of Galway Bay. The age of these rocks is very apparent, they 

 rest on a great anticlinal curve, the axis of which dips westward, 

 thus bringing up the oldest rocks to the westward, in the hill group 

 called Bennabeola. Some of the older rocks are lithologicalty identical 

 with the Laurentians of the district of Chelsea, Province of Quebec. 

 Yet these older rocks of Bennabeola have not been claimed as 

 Laurentians, although the younger rocks to the southward have 

 been — although the latter, from their fossils in the unaltered 

 portions, appear to be the equivalents of the English Llandeilo and 

 Bala series. 



CroaghanhinsTieUa. — Here the highly altered rocks occupy a small 

 tract at the meeting of the counties of Wicklow and Wexford, and 

 if lithological characters are conclusive, they ought to be included 

 among the Irish Laurentians, which up to the present has not been 

 done. Northward they have a hard boundary ; southward their 

 margin is obscured by superficial accumulations, but eastward and 

 westward they graduate into the rocks belonging to the upper 

 divisions of the Irish Ordovicians. 



Carnsore. — This is a small tract at the S.W. extremity of Ireland, 



