144 Proceedings of the Royal Irish Academy. 



of the southern coast line lying between Galley Head and the N. end 

 of Clear Island. 



The direction N'. 79° 11' E. corresponds very fairly with that of 

 the main barytes lode of Bantry, as described by Mr. Hardman in a 

 Paper read before the Eoyal Geological Society of Ireland in 1878. 

 He gives the direction of the main lode as 1^. 80° E. 



The direction JS". 78° 4' W. is not markedly present on the eastern 

 side of Ireland, but would fairly represent the line of contact of the 

 mica slates of Galway, lying to the north of the granite. 



The direction IS^. 43° 51' W. represents the southern shore of 

 Lough Erne, and also corresponds to a fault which runs from Lugna- 

 brick to Bengorm, Co. Galway. This direction would also apparently 

 be the dii'ection of the main lode of barytes situated in the S. W. 

 part of Cork, between Dunmannus Bay and Roaring Water, and stated 

 by Captain Triphook [Proceedings, Boyal Geological Society of Ireland, 

 vol. vi., p. 218, 1853-54) to be N. 45° W. 



XIY. — jS". 2°53'E. This direction is represented on the coast by 

 the line from Donabate to Shennick Island. It also corresponds with 

 the two faults limiting, east and west, a tongue of carboniferous lime- 

 stone which occurs at Kingscourt, and also with the fault marked as 

 extending between Knocktopher and Kilkenny city. 



XV. — jS". 87° 1' E. This direction represents very accurately the 

 northern coast of Galway Bay, between Clogmore Point and Salt Hill ; 

 and, being extended eastward, traverses the mass of trap rock which 

 occurs at Philipstown, and cuts the east coast on the north side of 

 Howth, where this direction frequently and markedly occurs (see 

 Proceedings, Pi.. I. Academy, 2 ser. vol. ii. Science, pp. 300-302). 

 It is also present at Donnybrook, in the Dodder bed, and, being ex- 

 tended thence westward, passes near Crumlin, where it occurs, and 

 crosses Galway Bay, so as to touch the northern end of Innismore Is- 

 land. The occurrence at Crumlin is remarkable. There occurs there a 

 sand-hill which has been worked for many years ; and on the escarped 

 face, at the south-west end of the quarry, there appears a rib or joint 

 having this direction, and which I take to be the result of the move- 

 ment of the soil in the manner of an earthquake. If this view be 

 correct, it would indicate that movements of ground, having given rise 

 to this line of jointing, took place subsequently to the formation of 

 these hills, which are presumably quaternary or even later. That a 

 great line of depression traverses Ireland from Dublin to Galway is 

 evident, whether represented by one single system of line of fi'acture 

 or by several remains for determination. To the south it represents 

 the southern shore line of Carrickaholt Bay, and the line of contact of 

 the old red sandstone with the carboniferous from Cork to Toughal 

 Bay. 



N. 60^ 19' W. represents the southern coast of Innismore Island. 



