Palwozoic Mocks of Galway and elsevjhere in Ireland. 349 



very similarly circumstanced, to be difterently treated ? Such as 

 the rocks iii the neighbourhood oi Petigo, on the north of Lough 

 Erne, as also the rocks of the small tract in N.E. Mayo, south- 

 ward of Charlestown, which in Griffith's and Jukes' maps are 

 marked as metamorphic rocks ; but which are grouped in Dr. 

 Hull's maps with the overlying unmetamorphosed fossiliferous 

 upper Silurians. In these metamorphic rocks the granitone ia very 

 similar to some of the Laurentian rocks. 



As the principal object of this paper is to treat of the tracts 

 with which I am more especially acquainted, I will not now 

 dwell further on the rocks of the above areas ; especially as the 

 arguments and facts already put forward elsewhere, in favour of 

 their being of Cambrian age, remain unanswered. 



County Wexford. 



The Wexford rocks mapped by me as Cambrians are divided 

 into two areas by a trough of Carboniferous rocks. In the area 

 to the S.E. of this trough or band, which may be called the 

 Carnsore district, the rocks, as a general rule, are more altered 

 than those to the N. and JST.W. of the band. No one can positively 

 assert that the rocks at both sides of the band are of the same 

 age; but, on account of the similarity between some of the 

 rocks in the Ballycogley section, and some of those northward of 

 the band, I believe all belong to one group ; and those to the 

 northward of the ba.nd are evidently Cambrians, as they contain 

 the characteristic fossil, Oldharnia. Dr. Callaway, indeed, does 

 not separate the rocks northward and southward of the band • 

 but he would wish to divide those in the Carnsore district into 

 groups of distinct ages. The rocks in this area are not well 

 exposed ; but by combining the sections on the coast at Cross- 

 farnogue and Kilmore Pier, with those at Ballycogley, near 

 Lady's Island Lake, and that along the east coast, a very fair 

 section across the whole can be constructed ; from which we learn 

 that there is a gradual merging from granite, through gneiss, into 

 schist, as the rocks are followed northward from the south coast. 

 Dr. Callaway suggests that there is an unconformability in the 

 Crossfarnogue section ; but this is impossible. He also states that 

 the unconformable boundary of the mass of metamorphosed 

 eruptive rocks, including agglomerates, near Greenore, prove that 



Sctbn. Pboc. R.D.S , Vol. iii,, Pt. vi. "J, E 



