Lower Palceozoic Rocks of the South-East of Ireland. 579 



over the whole of the area D, and over at least the southern part of the area F, 

 where the granite is now at the surface. On the supposition that the southern 

 part of the granite has biu'st through this trappean group, leaving it still deep 

 beneath the surface, we ought certainly, as we travel to the nortli and approach 

 the part of the district where the lower beds gradually rise to the surface, to 

 find this middle or trappean group cut across by the granite. 



It is true that, trappean rocks being irregular and uncertain in their occur- 

 rence, they may not have been deposited or formed among the aqueous rocks 

 vvhicli are penetrated by the granite about Tinahely, or in that part of the dis- 

 trict, wherever it may be, where the beds with which the traps are contempora- 

 neous are so penetrated. 



This is one explanation of the difficulty, though not a very satisfactory one, 

 and it is not I'endered more satisfactory when we come to examine a little more 

 in detail the contemporaneous traps of South Wicklow, and their associated 

 beds, and the facts connected with their abrupt termination towards the south- 

 west, or in the direction of the granite area. 



In the country on the east and south-east of Eathdrum a great number of 

 bedded traps and trappean ashes are to be seen interstratified with the slates, 

 all dipping steadily at a high angle to the south-east, and striking to the south- 

 west. Large, irregular, intrusive masses of greenstone also occur, but even these 

 have their greatest linear extension parallel to the strike of the beds. These 

 beds are three miles wide, measured across the strike, and whatever allowance 

 we may make for reduplication of the beds by concealed folds or repeated dis- 

 locations, there must be a thickness of at least several thousand feet, almost one 

 lialf of which apparently consist of the traps. But if we follow these beds 

 along tlie strike to the south-west, the traps all suddenly disappear as soon as 

 we come to a line running nearly N. and S. through Eathdrum, while in the 

 country to the west and south-west of that line nothing but granite and elvan 

 is to be found. 



The largest mass of felstone on the north-east strikes directly at the granite 

 of Ballinacarrig and Ballynaclash on the south-west, there being an interval of 

 scarcely half a mile between the two rocks, and both form comparatively narrow 

 bands running along the same line from N. E. to S. W. Farther to the south- 

 west several other detached granitic masses make their appearance, that of Cush- 



