SBQ 8cientifiG Proceedings, Royal Dublin Society. 



might be expected on account of the distance between the 

 places. As elsewhere, so 1 would now again point out that 

 the Laurentianists pin their faith too much on lithological 

 characters ; while they nearly altogether neglect petrological 

 or stratigraphical evidence ; and it would appear to me that if 

 they go on as they have began, we shall have, before long, every 

 metam Orphic region, no matter what the age of its strata, dotted 

 over with their Laurentian rocks. 



Note in Press. 



In a ;^aper on the " Geological age of the Taconic system," read 

 before the Geological Society of London, Professor J. D. Dana, in 

 opposition to the view that the geological age of strata can he inferred 

 from their mineral characters, pointed out what remarkably diiferent 

 rocks have been produced by the metamorphism, in different degrees, 

 of the strata of Taconic range. — Geol. Mag., New Series, Decade ii., 

 Vol. XX., page 282 (June, 1882). 



Description of Plates. 



Plate XXX. — Diagrammatic section of the rocks of the Bennabeola 

 mountains, showing the relations that originally existed between the 

 different series of strata that lie on the south and north slopes of the 

 great west and east anticlinal curve. 



Plate XXXI. — South and north section across the Bennabeola moun- 

 tains, showing the present position of the strata on the south and north 

 of the great W, and E. anticlinal due to their displacement by 

 numerous faults and breaks. The main west and east fault occurs in 

 the Clifden valley. It is a downthrow to the south, and here brmgs 

 down the younger rocks of the Middle micalite series (B 7) against the 

 much older rocks of the Quartzitic micalite series (B 3). 



Plate XXXII. — South and north section across the Corcogemore hills, 

 showing the present position of the strata on the south and north of the 

 great W. and E. anticlinal due to their displacement by numerous 

 faults. The main west and east fault occurs in the valley at the foot 

 of the south slopes of Corcogemore. Here it has not as great a south 

 downthrow as farther west. It brings down the rocks of the Great 

 micalite series (B 10) against those of the Ballynahinch series (B 8). 



