[ I02 ] 



THE SII.ICIFIKD WOOD OF I^OUGH NEAGH. 



BY WII.I<IAM SWANSTON, F.G.S. 



{Conchidtd froiti page 66. 



Dr. MacIvOSKie, in 1873, gave an elaborate paper to the 

 Belfast Natural History and Philosophical Society on the 

 silicified wood, and expressed his opinion that the spe- 

 cimens found in the drift were derived from beds of Miocene 

 age, and gave a fancy picture of a vast river flowing southward 

 over a continent of which the Hebrides and Western Islands 

 of Scotland form but a remnant, and this river brought the 

 partially silicified wood, and scattered it along its course. 



In the same 3'ear, 1873, the coal question was the all- 

 absorbing topic, and Mr. Wm. Gra}^ M.R.I. A., then Senior 

 Honorary Secretary of the Belfast Naturalists' Field Club, 

 gave a valuable paper on "The Lignites of Antrim and their 

 relation to true Cal." The subject was thoroughly gone 

 into, and many new facts were brought forward; perhaps one 

 of the most important being the discovery of silicified wood in 

 the basalt at Laurencetown, where, he states: — 



" There is a bed of Hgnite in the basalt about thirty feet from the sur- 

 face, and in this lignite there are layers of wood charged with siUceous 

 matter, and resembHng the wood erroneously supposed to be petrified 

 by the waters of I^ougli Neagh. This fact supplies the evidence Captain 

 Portlock admitted was wanting." 



After summing up all the evidence, which Mr. Gray puts 

 into a concise form, he comes to the conclusion that we can- 

 not escape the deduction that the beds of Ballypalad}^ Isle 

 of Mull, those near Shane's Castle, and at Laurencetown, 

 together with the silicified wood, and their associated lignites 

 of IvOUgh Neagh, are of the same age, — namely, Miocene, as 

 supposed by various writers. 



Taking the literature of the subject in its order, the next 

 reference we have to these lyough Neagh beds is that made by 

 the officers of the Geological Survey, and as their opinions are 

 of great weight, it is necessary to examine them carefully. 

 Sheet 47 and its explanatory memoir, describing the neighbour- 

 hood of Armagh, was issued in 1873. Sheet 35 and its ex- 

 planation, descriptive of the Tyrone Coal-fields, and the south- 



