146 



Proceedings of the Royal Irish Academy. 



traversed by greenstone or trap dykes, having practically the same 

 direction. It also represents the direction of the band of feldstone 

 which occurs to the south-west of Enniscorthy. 



N. 0° 56' W. This direction is in part represented by the line of 

 fault occurring between "Waterford and Kilkenny. It corresponds to 

 the theoretical line which is given by an angle of 70° with the Great 

 Circle (" South boundary, tertiary formation, United States"). 



XXI. — N. 63° 7' E. This direction represents the axis of Slieve 

 Caha Mountains between Bantry and Kenmare Bay ; as also the 

 direction of the line of contact of upper and lower silurian slates, 

 south-west of Killoughter. 



N. 66° 8' E. represents very correctly the remarkable tongue of 

 Old Red, which stretches from Bantry to Sheep Head, as also that of 

 the parallel line of contact on the south side of Dunmannus Bay. 



It may be of interest to bring together the directions which repre- 

 sent the faults, dykes, and remarkable joints observed ; and the fol- 

 lowing list gives the results for the two sets of observations : — 



No. of 

 observed Faults, Dykes, 



Directions. and remarkable Joints. 



Locality where 

 observed. 



Magnetic 

 Bearing. 



True 

 Bearing". 



416 Fault, 



Donabate Coast, 



4°-5'' E. 16°50'W. 



392 



Well-marked fault. 



Donabate Coast, 





r- 



-8° 



E. 



\ 









396 



Great fault, . 







T- 



-8° 



E. 











401 



,, ,, and cave, 







r- 



-8" 



E. 





13° 



50' 



W. 



403 



Great fault, . 



)) 





T 



-8° 



E. 











405 



>) )) • 



" 





r- 



-8° 



E. 



; 









342 



Great Dolomite joint. 



Malabide Coast, 





19°- 



-20° 



E. 



} 



1° 



5' 



w. 



388 



Dyke in slate rock, 



Donabate Coast, 





2 



r 



E. 



76 



Eurite dyke, 



Killiney TTill, . 





24" 



E. 



) 



T 



01^' 



V. 



423 



Fault, . 



Eush Strand, N. 



side 



25° 



-26^ 



E. 



) 









213 Great joint, 



Howtb, S. side, 



311 Great joint, witli lining, . Malabide Coast, 

 522 Great joint, connected "Woodlands, 

 with lode. 



28° 



31°-32° E. 

 32°-33° E. 



E. 6° 40' E. 

 ) 10° 40' E. 



