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has taken place, parallel to the course of the river, with a down- 

 throw to the zvest, greatest near Coleraine, and diminishing 

 southward, so as to vanish in the vicinity of Lough Neagh. 



It has been noted that the directions of the Roe and Bann 

 are northward, while that of the nearest large river, the Main, is 

 southward. It is also a notable fact that the Interbasaltic Zone, 

 east of the Bann, falls away southward from Tully Hill, near 

 Portglenone, where it is 550 feet above datum, to approximately 

 the lake level, say 50 feet above datum, near Cranfield Bay, north 

 of Lough Neagh. The Zone, however, falls away northward from 

 1,400 feet in Benbradagh, by fveady, to the sea-level at Downhill. 

 From these data corroboration is drawn for the commonly 

 accepted opinion that the directions of the present drainage were 

 initiated upon the surface of the Upper Basalt, after a series of subsi- 

 dences and dislocations, consequent upon the latest eruptions. To 

 such movements, no doubt, we may attribute the formation of the 

 Lough Neagh basin ; and amongst the many fractures distinctly 

 traceable, we may infer the existence of the fault running north- 

 ward by Coleraine. It lies along the torsion-line of a vertical 

 cosmic wrench, which sets adjacent parts of the original ground 

 at diverse inclinations, namely, that of the valley of the Main on 

 the east, and that of the Roe and Bann valleys on the west. 



The distance to which the Lower Basalt extended southward, 

 overlapped by the Upper, is not alone in itself an interesting 

 question, but possesses such importance, to my mind, in con- 

 nection with the age and formation of Lough Neagh, that I cannot 

 omit reference to it here, though the reference must necessarily 

 be brief. We have seen that the Interbasaltic Zone reaches 

 approximately the lake-level near Cranfield Bay at its north 

 margin. Passing to the Six-mile Water valley, we find felsitic 

 rocks at 190 feet above datum in Templepatrick, basaltic- 

 conglomerate, bole, and lignite in Ballymartin, and lignite with 

 leaf-beds at 200 in Ballypalady, all representative of the Inter- 

 basaltic Zone. Chalk, which appears at Templepatrick, seems to 



