8. Ilijde — Deep-mimng in the South-tvcsi of Ireland. 245 



lodes, underlays south, and materially influences the production of 

 mineral at its junction with the lodes. 



The district around Ballycumuiisk and the mino itself may ho 

 said to bo the only ])lace whero a thorough investigation has been 

 made so as to determine the nature of the rocks, and the quantity 

 and nature of the oojiper ores ; and the prosecution of this question 

 to its utmost will doubtless materially alter the general belief 

 that minerals of value are not to he toorhed at great depths in 

 the south of Ireland. This belief has been, and is now, held by 

 many, and the Memoirs of the Geological Survey, and especially the 

 peculiar views of the late Professor Jukes, have tended strongly to 

 mislead and deter either landowners or those possessing local interest 

 from investigation. 



In the Memoirs of the Geological Survey, explanation to sheets 

 200-3-4-5 etc., p. 27, in a " note on the mines of the south-west of 

 Cork," Professor Jukes, in mentioning the examination made by the 

 Survey over that district during the years 1853-6 (fifteen to seven- 

 teen years since,) is under the impression that the ores of coppei- 

 were deposited mechanically, so that " all tlie grits and slates were, 

 or are, here and there impregnated with copper ore, over all the 

 district stretching from Waterford through Cork into Kerry." " This 

 copper deposit was, like most materials deposited from water, not a 

 continuous sheet, but occurring in patches in different beds of grit 

 or slate through a thickness of 300 or 400 feet over all that area ; 

 '•the copper ore was distributed here and there among these beds as 

 a copper sand, or copper mud, mixed with the siliceous and argillace- 

 ous sands and clays.' " Professor Jukes proceeded to state that 

 " eventually these beds were greatly indurated — greatly disturbed 

 and tilted up into highly inclined, often vertical or even inverted 

 positions, and bent into numerous folds." 



These remarks apply to the deposition of the beds of grit and slate 

 that occur somewhat near the top of the lower division of the Old 

 Red Sandstone ; the lower portion of the yellow or upper Old Red 

 Sandstone of the south-west of Ireland, the " Copper Zone" of the 

 Geological Survey. Whatever may have been the particular mode of 

 original deposition, whether derived and deposited under aqueous 

 conditions or influence, so as to have impregnated tJie then mud and 

 sands, dc, but now slates and grit rock, with copper, it in no way 

 agrees with the concluding deductions drawn by Professor Jukes. 



Professor Jukes states his belief that the disturbances which 

 followed " must have been accompanied by many fractures, causing 

 fissures, some of which would remain more or less open below in 

 different parts of their course." He then goes on to say that "some 

 action subsequently determined the segregation of some of the copper 

 ore out of the beds into some of these hollow fissures, by some process, 

 of the exact nature of which we are ignorant, and thus new ' mineral 

 veins' or true lodes were formed here and there about the country." 



Now the great object of this communication is to show that, what- 

 Bver theories or hypotheses may be advanced to account for the origin 

 qf the ores or conditions of some lodes, there is evidence to show and 



