G. H. Kinahah — The Silurian Rocks of Ireland. 73 



including the Yellow Sandstone, the Old Red, and the Glengariff 

 Grits, might possibly be called a formation ; if it were not that north 

 of Dingle Bay there is a great break in the sequence, the upper 

 5000 or 6000 feet, only, extending continuously into the Carbon- 

 iferous rocks. Stratigraphically and paleeontologically this upper 

 portion belongs to the Carboniferous formation ; while the lower 

 portion, over 10,000 feet in thickness, stratigraphically belongs to 

 the Silurians, but palseontologically to the Carboniferous. 



It has been suggested that the Old Red Sandstone (Carboniferous) 

 of the Dingle promontory (2, Fig. 2) cannot be the same as the 

 Old Red Sandstone (Carboniferous) of West Cork (1, Fig. 2), as 

 such a change in their positions could not take place in so small a 

 distance as the width of Dingle Bay. This suggestion, however, is 

 not borne out by facts, as extending along Dingle Bay there is a 

 great fault with a downthrow to the northward, which, to the 

 eastward of the bay, brings down the Coal-measures against the 

 Old Red of the Cork type, and cuts out a thickness of strata more 

 than sufficient to account for a greater change. Elsewhere in 

 Ireland, as shown in the sections (Fig. 2), rocks having the Old Red 

 Sandstone characteristics, and, like it, graduating into the Lower 

 Limestone Shale, occur on different geological horizons. 1 



Note in Press. — Since this paper was read, Prof. Hull, in the 

 Geological Magazine, November 1st, 1878, published "A Possible 

 Explanation of the North Devon Section." Unfortunately for the 

 suggestions contained in it, there are various errors in reference 

 to the Irish rocks. 



All the Irish geologists who have studied the Dingle and Glengariff 

 Grits came to one conclusion about them, that is, that they belong to 

 one group, and Prof. Hull has now arrived at the same conclusion. 

 If this is allowed, we have a vast continuous series of rocks which 

 represents all the time intervening between the accumulation of the 

 typical Silurian of Dingle and the typical Carboniferous of Cork. This 

 necessitates some portion of this series of rocks being the equivalent 

 of the Old Red Sandstone or the Devonian rocks. Those that are 

 acquainted with the Old Red Sandstone (Griffith and Jukes) in the 

 country south of Dingle Bay are aware that it contains fossil plants 

 said by Baily to be also found at Kiltorcan, county Kilkenny, while 

 farther southward, near Toe Head, county Cork, and in the county 

 Waterford, the Kiltorcan fossils are well represented. The rocks 

 containing these fossils lie conformably on the Glengariff Grits, 

 while the latter also contain plants said by Baily to be of the same 

 type as some of the fossils of Kiltorcan. Thus these Old Red Rocks, 

 also the Glengariff Grits, according to Prof. Hull's reasoning, should 

 be of the same age as the Kiltorcan beds, and consequently Old Red 

 Sandstone. Yet this authority states that the Glengariff Gi'its are 

 certainly Silurians. 



An unconformability in the Cork rocks between the Carboniferous 



1 Its uncertain position induced the Rev. Dr. Haughton, in the year 1863, to 

 designate it a " Phantom formation." — Journal Geol. Soc. Dublin, 1863. 



