Weight — Palaeozoic Floor of North-East Ireland. 647 



Possibility of deterioration of the Lower Carboniferous Coals 

 to the South- West. 



We have yet to consider whether there is any chance of the deterioration 

 of the Ballycastle coals either in quality or thickness as they pass south-west 

 into these predicted areas, and it has to be admitted at once that there is a 

 distinct chance of this. I do not consider that much is indicated by the fact 

 that the seams in the Carboniferous rocks exposed at Dungiven are mere coal- 

 smuts, because they are in the very lowest beds of the formation, and the 

 same might be said of the lower strata of the Ballycastle coalfield. We must 

 remember, however, that between Ballycastle and Dungannon there is a gradual 

 passage from estuarine to clear-sea conditions, and that in proportion as the 

 estuarine conditions are replaced the coal must fail. At Maghera, just south of 

 the Highland border ridge, there is still a fairly thick mass of the Lower Lime- 

 stone above the sandstone and shale series, and we cannot see what happens 

 to the north-east of this. We can only hope that perhaps the Highland border 

 ridge itself has in some way formed a line of demarcation between the 

 predominantly estuarine conditions on the north and the predominantly open 

 sea conditions on the south. Again, in view of this possibility of deteriora- 

 tion I see a preference in favour of the Lough Foyle syncline as compared 

 with the Dungiven-Ballycastle syncline. 



Possibility of the occurrence of true Coal Measures in N. Antrim. 



No strata of Upper Carboniferous age are known anywhere within the 

 North Antrim basin, but this is hardly to be wondered at in view of the very 

 few exposures even of the Lower Carboniferous. The latter strata we know were 

 deposited here, and we can prove their continuity with the Lower Carboniferous 

 strata of the trough-valley by the series of exposures along the western margin 

 of the basalt plateau. If the sea in which the Lower Carboniferous beds were 

 laid down did not everywhere cover the Highland border ridge, it at least 

 broke through it in one place and occupied the basin to the north. Now the 

 Coal Measures are everywhere conformable to the Lower Carboniferous, so that 

 it is highly probable that the estuarine waters in which they were deposited 

 ■ covered the same area as the Lower Carboniferous sea, and even, in view of 

 the progressive submergence during Carboniferous times, a much greater area. 

 We may therefore assume that the North Antrim basin once contained Coal 

 Measures, and it remains to be considered whether any of them have escaped 

 the pre-Mesozoic denudation and are preserved as portion of the Palaeozoic 

 floor. 



Now, once more reverting for purposes of comparison to the Coal Island 



5i 2 



