OF THE NOETBT OF IRELATfD. 531 



conforma'bility upon those of the older series, yet in most places 

 they are distinctly, and often widely unconformable. I have endea- 

 voured to account for this discordance, in my description of the 

 district*, by the absence of a considerable thickness of rocks repre- 

 senting the Upper Old Red Sandstone, the lower series being con- 

 sidered to be Lower Old Red Sandstone, and the upper the basal 

 beds of the Carboniferous system. I was the more inclined to adopt 

 this view from the remarkable resemblance in so many points of the 

 lower series of conglomerates &c. to those classed as Lower Old 

 Red Sandstone in Scotland (a resemblance which Professor Ramsay 

 also mentions in the preface to the memoir just referred to), and 

 from the similarity of the quartzose conglomerate series to many 

 others in various parts of Ireland, which, though formerly considered 

 to be Old Red Sandstone, have for many years past been classed in 

 the Carboniferous system. 



In Scotland, as mentioned in the very able monograph on the 

 Old Red Sandstone by Dr. Geikie, discordance exists, which Sir 

 R. Murchison accounted for by the absence of a group of rocks 

 representing a Middle Old Red Sandstone period, a view in which 

 Dr. Geikie does not concur f. 



Some time ago Mr. Kinahan drew attention to the similarity in 

 geological position of the lower conglomerates of Tyrone (Fintona 

 beds) to that very remarkable group of rocks in the south-west of 

 Ireland called the Dingle beds, which, resting conformably upon 

 Upper Silurian rocks, are overlain unconformably by conglomerates 

 and sandstones, which have always been regarded as the true Old 

 Red Sandstone. The sequence upwards from the Silurian rocks 

 could not be proved in Tyrone ; but it became an important matter 

 to settle definitively if possible the position of the upper conglo- 

 merates. If these were found to be identical with those called Old 

 Red Sandstone in the south of Ireland, Mr. Kinahan's view must be 

 held to be correct in relegating what has been called the Lower Old 

 Red Sandstone of TjTone to the horizon of the Dingle beds. During 

 a short tour which, owing to the kindness of Professor Hull, I was 

 permitted to take through the south of Ireland last summer, I had 

 opportunities of seeing many sections through the Old Red Sand- 

 stone of that district. At Waterford the basal beds of that forma- 

 tion were seen resting almost horizontally on vertical slates of 

 Lower Silurian age, forming a very striking feature in the cliffs 

 over the railway-station ; they are massive quartzose conglomerates 

 of a dark purple to reddish-brown colour, the contained pebbles 

 being almost exclusively of white and pink quartz and quartzite, 

 perfectly identical with the upper (the so-called Carboniferous) con- 

 glomerates of Tyrone. In the valley of the Blackwater at Lismore 

 the upper parts of the series were seen, and consist of massive grey 

 and purple sandstone, closely resembling certain beds in the " Car- 



* See G. S. Memoir just quoted. 



t Professor Hull believes that the absent beds are the Marine Devonians 

 (Lower and Middle). 



2o2 



