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



the following year. When the plants were pronounced by Salter to 

 be of Carboniferous types, 1 Jukes considered the question to be finally 

 settled ; Griffith however said, " Wait till the Dingle district is 

 examined, and you will find, that although the plants are of 

 Carboniferous types, the rocks are Silurians." 



When the Dingle peninsula was examined by Du Noyer, Foot, 

 and Wynne, it was found that while there was a great unconform- 

 ability between the lower and upper divisions of the strata called 

 Old Red Sandstone, a complete conformability extended from the 

 lower division downwards into fossiliferous Silurians, and from the 

 upper division upwards into the Carboniferous Limestone and the 

 Coal-measures. In the lower division, however, no fossils could be 

 found, 2 and these strata were called " Dingle beds," — a title which 

 involved no assumption as to their age. To this lower division, 

 according to both Griffith and Jukes, the above-mentioned rocks near 

 Killarney, near Valencia, and in West Cork, belong 



Subsequently these rocks were examined conjointly by Griffith, 

 Murchison, and Jukes ; and some of the party visited not only Cork 

 and Kerry, but also Galway and Mayo. After this exploration 

 Murchison was inclined to side with Griffith ; but the plants were a 

 stumbling-block. Furthermore the late Mr. John Kelly showed 

 that the Dingle beds have the same stratigraphical position as the 

 rocks mapped as Old Red Sandstone in the Curlew Mountains (cos. 

 Sligo and Roscommon) and about Fintona (cos. Fermanagh and 

 Tyrone) ; while the Curlew and Fintona rocks are lithologically 

 similar to the Old Red Sandstone of the Commeragh, Galtee, and 

 Knockmeeldown Mountains ; the classification of the just-mentioned 

 Cork and Kerry rocks therefore was left an open question until the 

 rocks in Mayo, Roscommon, Sligo, Fermanagh, and Tyrone, 

 suggested by Griffith to be of the same age as the Dingle beds, were 

 examined. 



The question remained in abeyance while the officers of the 

 Geological Survey were examining the rocks of North-east Munster ; 

 until about 1864, when Foot declared that he suspected the rocks of 

 the Curlew Mountains to be "Dingle Beds." The following year 

 Jukes examined those rocks for himself, and subsequently announced 

 his belief that the lower portion of the so-styled Old Red Sandstone, 

 near Ballaghaderreen, to the west of the Curlews, was probably of 

 the same age as the " Dingle Beds," as it seemed to lie conformably 

 on similar fossiliferous Silurians, as previously stated by Kelly, 

 while it was similarly capped unconformably by what all would 

 regard as true Old Red Sandstone (Carboniferous). Still it was 

 premature to say what its age might be until it and all the tracts 

 mentioned by Griffith had been systematically examined. 



At this time I began the work in West Galway and Mayo, and, 

 after seven years' careful examination, I came to the conclusion that 



1 Mr. "W. H. Baily has recently examined the plants from these localities in the 

 Glengariff Grits. 



2 I have since learned from Mr. 0' Kelly that fossils, like plant-stems, were subse- 

 quently found in the Dingle beds. 



