Kinahan — On Granite and Met amorphic Mocks. 181 



less calcareous, containing, in some places, nodules of limestone, while in others they 

 merge into impure limestone. That these were contemporaneous protrudes is prohahle, 

 hecause in places they extend into interhedded sheets and lentals. In the upper group 

 (Kilmichael or Slate Series) there are also whinstones generally occurring as protrudes, or 

 intrudes (?), some of which have been changed by methylotic action, into serpentine 

 (pphyte), soapstone (steatt/tc), or some allied rock. The exact age of the youngest in- 

 trusive rocks is uncertain, as where they occur there are no rocks newer than 

 Ordovician, by which their age might be determined. Some, however, are probably of 

 later than Ordivocian age, as hereafter mentioned. Jukes appears to have been the first 

 to point out that some of the schists, especially the hornblendytes, are metamorphosed 

 intrusive rocks. Usually, if a course of whinstone has been metamorphosed, the central 

 rib is changed into hornblende rock or hornblendic gneiss, while the margins have 

 become hornblendyte (hornblende schists). Matthews, of Baltimore, when writing of the 

 American rouks, suggests the alteration to be due to metamorphosis, or molecular dis- 

 placement, and Dr. Teall more recently has come to a similar conclusion. Examples of 

 such alterations can be seen in the courses of whinstone in various places in the more 

 highly altered rocks of S.E. Ireland (Dublin, Wicklow, and Wexford), those of Con- 

 naught (Galway, Mayo, Sligo, Leitrim, &c), those of Ulster (Donegal), and in those of 

 North America (Dominion and States). In other places that I have not seen similar 

 changes may have taken place. Some of the ophytic-hornblende rocks, among the 

 highly metamorphosed rocks, are very similar in aspect and composition to the so-called 

 " Swedish green granite."] 



Materials for Glass. — Associated with the masses of exotic rocks 

 there are, in places, granites which graduate into elvan ; some of 

 the latter, already mentioned as at the Little Bock, Arklow, are 

 very felspathic, and eminently suitable to be used in the manufac- 

 ture of glass. Some of the elvan veins, and the granityte veins in 

 the Leinster granite, or in its vicinity, are also very felspathic, and 

 might be similarly utilized. 



Llandovery, or May Hill Sandstone (Post- Ordovician and 

 Pre-Siturian). Granites, Elvans, Quartz-Rocks, Felstones (?) 



[In the Leinster hill range the granites are lithologically very varied, but petro- 

 logically they seem to be divisible into the following, viz. : — Leinster Type ; the 

 Aughowle Type, or pegmatyte, similar to that occupying the parish of Aughowle; and 

 the Augheim Type, best seen in the vicinity of Aughrim. 



The " Leinster Type " granites (Haughton) are evidently the oldest, and seem to be 

 intrusive, the date of their intrusion being after the accumulation of both the Cambrians 

 and the Ordovicians. They have all the general characters of an intrusive granite, 

 and at their margins break up through the schist. Nevertheless, in various places, 

 such as Scullogue Gap, between Mount Leinster and Blackstairs, and elsewhere, 

 there are in the granite, seams, or lenticular beds of schists, coinciding in strike and dip 

 with the "grain" of the granite. These are difficult to account for in an intrusive 

 mass; yet that the mass is intrusive seems unquestionable ; because if we cross the strike 

 of the " grain 1 ' at right angles, this grain is found to be oblique and unconformable to 

 the stratification of the marginal schists. When describing these inliers of schist in the 



