142 Proceedings of the Royal Irish Academy. 



direction of the Glenmalure and Avonbeg rivers, down to the Meeting 

 of the "Waters. 



VIII. — N. 29° 15' "W. This direction corresponds to certain dykes 

 marked as occurring in the Co. Armagh ; also with the fault lying to 

 the E. of Gallion Meigh (Mourne Mountains) ; also with the southern 

 part of the fault represented by the direction of the Newry canal ; 

 also with dykes at Rosstrevor and others to the E. in the district of 

 Mourne. It represents very accurately the direction of the coast line 

 from Donaghadee to Bruce's Castle on the N. E. point of Rathlin Island. 

 The direction parallel to this, which passes through Lough Neagh and 

 Innishowen, Co. Derry (an earthquake locality), traverses Iceland at 

 Hecla, or in the immediate vicinity, and on its extension to the S. 

 would correspond with the western coast line of the department of 

 La Manche in France. 



IX.— N. 6° 5' W. 



X. — N. 69*^ 57' E. This direction is remarkable from many points 

 of view. It occurs at Palmerstown, and being thence extended to the 

 S. "W., it will be found to correspond very exactly with a line of fault 

 marked as occurring in Mount Erin, King's and Queen's Cos., this in 

 its extension to the S. W. passes along the S. side of the mouth of the 

 Shannon. A parallel to this direction from Feltrim, where this system 

 of jointing is observable, corresponds very exactly with the direction 

 of the N. side of the Shannon mouth, between Kilclogher Head and 

 Corless Point, corresponding also with the line of contact of the old 

 red sandstone and carboniferous formations to the S. of Lough O'Grady, 

 Co. Clare. This line I had deduced theoretically from the great circle 

 ("Southern boundary of tertiary formation, United States ") by the 

 angular relation, 40°, which it makes therewith. It also corresponds 

 very correctly with the marked line of faulting indicated as occurring 

 in the Kilkenny and Carlo w coal-field. It furthermore corresponds 

 with the junction of the carboniferous limestone, with the granite and 

 lower Silurian in the Co. Dublin, between Roebuck and Allenton ; also 

 with the trap dyke system of the Co. Waterford. Lastly, it represents 

 the direction of the southern coast line of Ireland, from Carnsore Point, 

 in Co. Waterford, to Galley Head, Co. Cork. 



XL — N. 47° 05' "W. This direction represents the Balbriggan 

 coast, from Shennick Island to opposite Cargee Eocks. 



XII.— N. 39° 57' W. and N. 30° 30' E. The very remarkable 

 direction N. 30° 30' E. is that of the eastern boundary of the granite 

 mass which traverses the counties Wicklow and Carlow. It is also 

 that of the eastern boundary of the chloritic slates of the Co. Water- 

 ford from Tramore to Waterford. It also represents accurately the 

 direction of the patch of old red sandstone occurring in the eastern 



