G. H. Kinahan — The Silurian Rocks of Ireland. 67 



the oldest rocks there are Cambrians. These are partially covered, 

 as it would seem conformably, by Cambro-Silurians. Resting un- 

 conformably on both of these are newer rocks, some of which years 

 ago were proved by their fossils to be Silurians, but others for a 

 time were considered to be Old Eed Sandstone. All of these are 

 capped unconformably by acknowledged (Carboniferous) Old Red. 

 Sandstone. 



The rocks extending from Loughs Corrib and Mask by Maum to 

 the Atlantic on the south of Killary Harbour had for j'ears been 

 known to be Silurians ; but the rocks between Toormakeady on 

 Lough Mask and Mweelrea north of the mouth of Killary Harbour, 

 as also an isolated tract further north near Louisburgh, were at one 

 time supposed, on account of their lithological character, to be Old 

 Eed Sandstone. Griffith, however, found Silurian fossils at Toor- 

 makeady, while subsequently I also found them in somewhat similar 

 rocks in the Mweelrea Mountains. It was either during the ex- 

 ploration in which Griffith found the fossils at Toormakeady, or on 

 a subsequent occasion, that he came to the conclusion that all 

 were of Silurian age ; the Louisburgh beds being the newest, and 

 the representatives of a portion of the Dingle Beds. 



To the northward of Toormakeady, in the neighbourhood of 

 Croaghmoyle, there is a large tract of rocks, that Jukes, Symes, and 

 myself were convinced to be of about the same age as the Toor- 

 makeady conglomerates, although it was marked on Griffith's map 

 as Old Red Sandstone. This led me to seek for an explanation, and 

 when my maps and sections were so far complete as to be intelligible, 

 they were carefully examined and considered by Griffith. Subse- 

 quently I waited on him, by appointment, and in our conversation 

 I learned that the marking of that district, as also of others, on his 

 map, as Old Red Sandstone, was done in compliance rather with 

 received opinions, than with his own conviction. That, in the so- 

 called " Old Red Formation " in Ireland, there was a marked uncon- 

 formability, — part of it extending downwards conformably into the 

 Silurian, and part of it upwards into the overlying Carboniferous 

 rocks. That the rocks of West Cork, and adjoining portions of 

 Kerry, of Dingle, of Toormakeady, of Mweelrea, of Louisburgh, of 

 Croaghmoyle, of the Curlew and Fintona Mountains, he believed to 

 be of nearly similar Silurian age. Those in the West Cork and 

 Kerry, Dingle, Toormakeady, Mweelrea and Louisburgh, he had had 

 time to examine properly, and had mapped them as Silurians, 

 while the rest he had not so carefully examined. But in deference 

 to Portlock's authority, and also because they were lithologically 

 more or less similar to the Old Red Sandstone (Carboniferous) of 

 the Knockmeeldown, the Galtee, and Commeragh Mountains, he 

 left them as Old Red Sandstone. At the same time, he pointed 

 out — "The Toormakeady Conglomerates are also similar, yet I found 

 Silurian fossils in them." x In this conversation he also stated : 



1 Strictly, these fossils are not in the Conglomerates, hut in the beds below them. 

 As yet, in no place above the Tooimakeady Conglomerates have fossils been found, 

 except, perhaps, in the green tuff at Mount Partry — its position, however, is 

 uncertain. 



