G. H. Kinahan — The Silurian Rocks of Ireland. 65 



Hills, which also rest on the same basalts, and contain plant-remains 

 similar in general character to those in the Lough Neagh clays. In 

 the absence, however, of full lists of the flora of both beds, nothing 

 more definite can at present be stated regarding their identity. 

 Should subsequent researches prove them to be the same, it may 

 safely be inferred, that one reason why the Lough Neagh beds still 

 retain their clayey character is owing to the simple fact that the 

 later outflows of Miocene basalt did not reach them, and convert 

 them into iron-ores, etc., similar to those so largely developed to the 

 east and north of County Antrim. 



Although not strictly connected with the subject, I may be allowed 

 to refer to the much-vexed question of the origin of the silicified 

 wood of Lough Neagh. Dr. Barton was most probably right in his 

 statement, made in 1751, 1 that the celebrated fossil- wood was found 

 in association with the black lignites. His descriptions of over a 

 hundred specimens — many of them figured in his work, most of 

 which were part wood and part stone — cannot be ignored ; and 

 although only a few of these were obtained direct from what seemed 

 to be the true Lough Neagh beds, yet many were so intimately 

 associated with the lignite, the origin of which is not disputed, that 

 considerable weight still attaches to his quaint descriptions. 



I have in my possession specimens, portions of which still retain 

 their woody character, in no way different from the more solid pieces 

 of lignite. One piece was found intimately associated with the 

 lignite and white-clay beds ; and in the same place was also found 

 one of the numerous ironstone nodules, derived from the same clays, 

 which contained a piece of silicified wood and other plant-remains. 

 Scattered through the Boulder-clays of the district for miles around 

 may be found pieces of the lignite, which testify to the vast amount 

 of denudation which the older beds have suffered. Associated with 

 them, but much less abundant, may be picked up the silicified speci- 

 mens, the angles of which are quite sharp, and showing no evidence 

 of distant origin. 



III. — The Silurian Rocks of Ireland and their Relation to 



the Old Red Sandstone. 2 



By G. H. Kinahan, M.R.I. A., etc. 



A QUARTER of a century ago it was a disputed question whether 

 the Old Red Sandstone was a separate formation or not. 

 About that time, or a few years later, the subject engaged the 

 attention of the Geological Section of the British Association. 



When I joined the Geological Survey, Sir R. Griffith had mapped 

 the older rocks in West Cork as of Silurian 3 age, while Jukes was 

 inclined to class them as Old Red Sandstone. Plant-remains 

 were found in rocks of the same series in the Killarney district by 

 Du Noyer in the summer of 1855, and near Valencia by myself in 



1 Dr. Barton's Lectures on Natural Philosophy ; Lecture 3, Metamorphoses, p. 51. 



2 Bead Nov. 18th, 1878, before the Royal Geological Society of Ireland. 



3 In this paper jukes' nomenclature is followed ; the formations being called 

 Silurian and Cambro- Silurian instead of Upper and Lower. 



DECADE II. VOL. VI. — NO. II. 5 



