Kinahan — On Irish Metal Mining. 273 



Limestone of the Central plain. Under the Carboniferous Slate is 

 the Yellow Sandstone (Griffith) or Upper Old Red Sandstone (Jukes): 

 it graduating downwards into the Devonian or Lower Old Red 

 Sandstone, and the latter into the Glengariff Grits (Jukes) or 

 Silurian (Griffith). The equivalents of the groups, as nearly as 

 possible, are as follows: — 



Cork Type. Central Ireland Type. 



( Carboniferous limestone and 

 4. Carboniferous slate. . . . { T r , i , 



J [ Lower limestone shales. 



3. Yellow sandstone, . . . Lower carboniferous sandstone. 



2 * { Low°eToid Eed Sandstone, j Lower r>evonian ( ? ) (England). 

 1. Glengariff Grits, .... Silurian. 



The Glengariff Grits are evidently the representations of 

 the upper beds of the Silurians of the Dingle promontory, Co. 

 Kerry. The Devonian {Lower Old Red Sandstone) are in part the 

 equivalent of the Lower Devonians of England. In Co. Cork 

 they form a regular unbroken passage from the Carboniferous rocks 

 down into the Silurian ; but in Slieve Mish, Co. Kerry they 

 are only in part represented, the lower strata being absent, while 

 the higher ones lie direct, but unconformable, on the Dingle 

 Silurian. 1 Elsewhere in Ireland, except, perhaps, the Fintona 

 Mountains, counties Fermanagh and Tyrone, the Devonian rocks 

 are not represented. 



The Yellow Sandstone (Upper Old Red Sandstone) 2 is an im- 



1 In Slieve Mish, above the unconformability ("Inch or Park conglomerate"), 

 and below the Lower Limestone Shales, there is a thickness of some 5000 feet of 

 strata. These must represent part of the rocks (called by me Devonians) below the 

 Carboniferous Slate, Co. Cork. This fact seems to be ignored in the proposed new 

 classification of the Cork rocks. 



2 Jukes' names for the Cork rocks, Upper and lower Old Red Sandstone, has been 

 the cause of considerable controversy in the Mining Community, they apparently not 

 understanding that they are petrological or group names, and do not specially refer to 

 lithological characters, and that the rocks of the groups may be either argillaceous {shales 

 and slates) or arenaceous {sandstones). In Jukes' groups, as a general rule, argillaceous 

 rocks {Killas of the miner) are more prevalent in the Upper, and arenaceous rocks form 

 the majority in the Lower. In the Yellow Sandstone, or Upper Old Med, of the 

 Co. Cork most of the Copper veins occur, they not being of any value in the Lower 

 Old Red. 



SCIEN. FEOC, E.D.S. — VOL. V. PT. IV. 



u 



