KiLROE — Silurian and Metmnorphic Rocks. 



153 



is consistent with the fact that the Curraghrevagh lava and associated 

 conglomerate seem to dip under the limestone band wliicli occurs at 

 the west end of Lough Kafooey. The lavas of the hill just mentioned 

 and of Bencorragh may therefore represent lower horizons than Bala ; 

 and the same may he said of some of the associated conglomerates 

 here, as at Leenane, which will hereafter he described. That they 

 are not of later date is fairly certain ; yet the representatives of 

 the Cregganbaun group south of Tourmakeady in Kilbride and at 

 Bencorragh, rest against the lavas mentioned and their associated 

 conglomerates. The geology of this locality is so important that a 

 reduced view of the working 6-inch map is here given. It will be 

 noticed that the neiver rocks are here in places set vertically, which 

 may be borne in mind in view of overfoldings which must be referred 

 to later. 



That a strong unconform ability occurred, probably in Llandovery 

 times, which involved the denudation of strata belonging to this age, 

 and much of the Lower Silurian series, where Wenlock strata now 

 exist, cannot therefore be questioned. In consequence of the 

 denudation, the floor of this group seems to consist for the most 

 part of metamorphic rocks of Dalradian age rather than of Lower 

 Silurian strata. Thus, representatives of the Cregganbaun group are 

 to be met with along the southern margin, resting directly upon 

 metamorphic grits and mica-schist; and, towards Maam, the fossil- 

 bearing zone appears at several points, accompanied in the valley 

 south-east of Leenane by conglomerate, which is distinguished, as 

 at Cregganbaun, Knockfadda, and several other points, by being made 

 up chiefly if not entirely of well-rounded pebbles and blocks of 

 quartzite. This conglomerate is traceable across the rugged tract 

 westward, growing in importance towards the sea-coast in its course 

 by Lough Fee and Garraun Hill. 



A section drawn northward a short distance west of Leenane 

 traverses an ascending series of Wenlock and Ludlow strata in 

 regular sequence, not Llandovery, followed by Ludlow, as was for- 

 merly supposed; and beyond the Ludlow outcrop of some 1,200 

 yards in width is encountered one of the greatest dislocations, if 

 not quite the greatest, in this much -faulted area. It is probably 



volcanic activity to a somewhat later date. The same may be said with regard to 

 some agglomerate -like breccias which I noticed in the Kilbride igneous tract. See 

 Paper on similar masses in S,-E. Ireland, by A. McHenry, m.k.t.a., and J. R. 

 Kilroe, Jour. Geo. Soc, vol. Ivii., p. 479 ; and the recently issued Memoir of the 

 Limerick District, pp. 33 et seq. 



