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



of the carboniferous series, some of which contain calamites 

 and many obscure casts of bivalves, one of which was named 

 by Mr. Sowerby as the Avicula modiolaris *. The upper 

 beds of the sandstone alternate with a dark-gray, and occa- 

 sionally blueish-gray qtiartzose-rock, and they are succeeded 

 by dark-gray clayslate, alternating with carboniferous lime- 

 stone. These strata, at Riversville quarry, which I have 

 lately visited, dip to the east at an angle of 15. It was here 

 that Mr. Weaver could discover traces only of the graywacke 

 formation; now the upper part of the quarry just mentioned 

 contains thin beds of carboniferous limestone; and imme- 

 diately to the south and east we have large quarries of that 

 rock partaking of the same strike and dip as the schistose 

 beds beneath it, which rest conformably on the strata belong- 

 ing to the old red sandstone series of the Slieve Meesh range. 

 How Mr. Weaver can consider beds in such a situation to 

 belong to the transition series, I cannot understand ; for, as to 

 his idea of there being a protrusion f of graywacke from be- 

 neath the old red sandstone, it cannot be sustained, there 

 being no reverse dip ; on the contrary, the yellow sandstone 

 and dark-gray slate rest conformably on the old red slate, 

 and are succeeded by strata of limestone having the same 

 strike and dip |. 



In regard to fossils in the yellow sandstone and carbonife- 

 rous slate of this locality, as I mentioned in my paper which 

 has been quoted by Mr. Weaver, they contain numerous im- 

 perfect casts of Producta^ Spirifera, Tercbratula, Crinoidea, 

 and Retepora; but though I lately sought, with much care, I 

 did not discover any varieties of Orthis or Favositcs, supposed 

 by Mr. Weaver to occur there. 



The foregoing description of the structure of the Cahir- 

 conree, or Slieve Meesh range, is similar to that contained in 

 my paper just alluded to, which has been verified by recent 

 observations ; but as Mr. Weaver was not convinced of the 

 inaccuracy of his views respecting the carboniferous slate at 

 the eastern base of the Slieve Meesh range, which, notwith- 

 standing my section and description, he still considered to 

 belong to the graywacke series, I do not expect that what I 

 now repeat will have the effect of changing his opinion. But 

 it should be observed, that this carboniferous slate, which un- 



* Journal of the Geological Society of Dublin, vol. ii., part 1. 



t See Lond. and Ed. Phil. Mag. for April, p. 291. 



J In my section already alluded to, the lithographer did not make an 

 accurate copy of the original, and has made the limestone strata to rest un- 

 conformably upon the carboniferous slate, while in nature these strata are 

 conformable. 



