OF THE KOCKS OF THE SOUTH OF lEELAND. 257 



Thirdly. I shall offer some observations on the points of analogy 

 and contrast between the Old Eed Sandstone of the South of Ireland 

 and its lepresentatiyes in North Devon, Belgium, and Scotland. 



Foiirtlily. I shall endeavour to show the true position in the 

 region of " Siluria " of the Old Red Sandstone on the one band, and 

 the equivalents of the Glengariff beds on the other, and indicate the 

 geological position of the " Cornstone " group in the Devonian series, 

 and conclude with some general observations. 



III. Caebonifeeoits and Old Eed Series. 



Descending Series in tTie South of Ireland and N. Devon. — In order 

 to prepare the way for the consideration of the first thesis, it is 

 necessary to give a brief description of the descending series imme- 

 diately underlying the Carboniferous Limestone in the districts of 

 the South of Ireland and North Devon, and by comparing them 

 together to obtain a clear idea of the position of the hiatus as 

 it occurs in the former district. In this comparison my views are 

 happily in unison with those of the late Professor Jukes*, the late 

 Mr. Saltert, and (I believe I may also say) of Mr. Champernowne, 

 F.G.S., who has devoted so much time to the study of the rocks of 

 Devonshire +. The only objections wbich can with any plausibility 

 be urged are those based on the occurrence of fossils in the one 

 district not found in the other ; but all such objections seem to me 

 to disappear when the important differences which were prevalent 

 in the physical geography of these districts respectively are taken 

 into consideration. 



The descending series of beds below the Carboniferous Limestone 

 in both districts having been frequently and fully described, only a 

 brief summary is here necessary. I shall commence with that in 

 the South of Ireland. 



Descending Series, South of Ireland. 



Carboniferous Limestone. Coralline, crinoidal, and shelly limestone ; 



sometimes cleaved (thinning towards the south-west). 

 Carboniferous Slate {top beds). Black slate with calcareous bands full of 



fossils (2). Black and grey slate, with few fossils (1). 

 Coomhola Grit. Grey and olive-green slates and tiles with fine-grained 



hard grey grits, with marine shells and some plants, the whole having 



a maximum thickness in Co. Cork of 5000 feet§. 

 Old Red Sandstone\\. (a) " Kiltorcan beds;" fine-grained, yellowish, 



* " On the Carboniferous Slate," «fcc., Quart, Journ. Geol. Soc. vol. xxii. 

 p. 348, &c. t Ibid. vol. xix. p. 474. 



X "The Devonian Question," Geol. Mag. March 1879. 



§ Jukes and Geikie, Man. Geol. p. 586. 



II The Old Eed Sandstone with the Kiltorcan beds at the top and the con- 

 glomerate at the base is the "Upper Old Red Sandstone" of Scottish geolo- 

 gists, which "graduates upwards into the Lower Carboniferous Sandstones," as 

 stated by Professor Geikie ("The Old Red Sandstone of Western Europe," 

 Trans. Roy. Soc. Edinb. vol. xxviii.) ; the " Lower Old Red Sandstone and Con- 

 glomerates" of Lesmahago and the Pentlands is doubtless the representative 

 of the Glengariff or Dingle beds, as suggested by Prof. Geikie ; but the ques- 

 tion remains. Are they not really of uppermost Silurian age ? 



