86 Reports and Proceedings. 



The authors discussed the several theories that may be sug- 

 gested to account for the origin of the present condition of the piso- 

 litic ore, and proceeded to point out what appear to have been the 

 several stages of metamorphic action by vp^hich the pisolitic ore had 

 been elaborated out of basalt. Erom field observations and chemical 

 analyses they have been led to consider the bole and lithomarge as 

 the resultants of aqueous action in combination with acidulated 

 gases, which, dissolving out certain mineral substances, have effected 

 the decomposition of the basalt ; and to assume that the bole 

 underlying the iron band was a wet terrestrial surface, and that the 

 subsequent outflow of basalt effected (by its heat, pressure, and 

 evolved gases) a reduction of the contained oxides of iron into the 

 more concentrated form in which they occur in the pisolite, the 

 aggregation of the ferruginous particles being a result of the same 

 actions. 



The ferruginous series, with interstratified plant-beds at Bally- 

 palidy, was next described, and demonstrated to be of sedimentary 

 origin ; the ferruginous conglomerate resulting from the degrada- 

 tion of the pisolitic ore, of which it is chiefly reconstructed, and of 

 the underlying ochres. 



Many additions were made to the list of plant-remains from these 

 beds ; and priority of discovery of plants in the Antrim basalts was 

 accorded to Dr. Bryce, F.G.S. 



Discussion. — Mr. B. Forbes was not prepared to admit some of the theoretical 

 conclusions of the authors, and objected to calling in metamorphism to accoimt for 

 ail that was hard to be understood. He could not recognize the division of beds 

 so similar in character into two classes. He wished to know, assuming that the 

 iron-ore merely resulted from the decomposition of the basalt, what became of all 

 the silica and alumina which constitated three-fourths of the mass. The origin of 

 pisolitic ores was in fact organic. In Sweden certain lakes were regularly dredged 

 each year for the pisolitic ore still in course of formation by means of confervoid 

 algae. He therefore regarded the whole of these beds as in a certain sense sedi- 

 mentary, and though due to organic agency, yet still deriving their original 

 mineral matter indirectly from the basalt. The basalt contained a considerable 

 amount both of phosphorus and sulphur ; and if the ores had been derived directly 

 from the basalt, both these substances would have been present in them. This was 

 an argument against any direct metamorphism. The presence of vanadium afforded 

 additional reason for regarding these ores as fonned in the same manner as bog 

 iron and similar ores. 



Sir Charles Lyell had observed in the basalts of Madeira red ochreous bands, 

 which represented old land surfaces, in one of which Mr. Hartog and he had dis- 

 covered a leaf-bed containing vegetation of much the same character as that of the 

 island at the present day. Near Catania, in a recent lava-stream, he had seen the 

 junction of the lava with the soil of the ancient gardens ; and in character the soil 

 now under the lava resembled the red beds in Madeira. 



Mr. W. W. Smyth was on the whole inclined to admit the power of metamor- 

 phism to produce such changes as had been here effected. He commented on the 

 advantages of employing this Irish ore for admixture with hsematitio ore, on account 

 of the abundance of alumina present. Possibly there had been some difference in 

 the chemical character of the different flows of basalt. 



Mr. Evans suggested that the Ballypalidy beds might bo the littoral deposits of 

 a lake in which the pisolitic ores of the other parts of Antrim were deposited 

 further from the shore, and subsequently buried under a basaltic flow. 



Mr. Etheridge inquired whether the pisolitic ore had been subjected to microscopical 

 examination, with a view of finding traces of organic forms, such as Gallionella. 



Mr. Tate, in reply, defended his views as to metamorphic action. He thought 



