636 Scientific Proceedings, Royal Dublin Society. 



Red Sandstone. The continuation of this belt beneath the basalt plateau 

 of Antrim is less likely to be productive than the rest of the trough, so that 

 it becomes necessary to draw a new line cutting off the belt of sandstone, 

 and consider this as the north-westerly limit of probable coal-fields. In a 

 later paragraph it will be necessary to consider the evidence in favour of a 

 modification of this line allowing of the possible occurrence of coal-bearing 

 strata further to the north-west; but in all preliminary exploration it should 

 be accepted as a limit, as the probability of finding coal is undoubtedly much 

 greater to the south of it. 



Arrangement of Coal-Basins along the Trough- Valley. 



Now, considering the lowland valley of Scotland once more, we see that 

 the Coal Measure basins lie at intervals along it, and are separated from one 

 another by arches of older Carboniferous and Old Eed Sandstone rocks. The 

 basin which lies neatest to Ireland, the Ayrshire coalfield, is a well-defined 

 trough, having a north-westerly axis across the course of the central valley, 

 and is bounded on either side by equally well-defined ridges of older rocks, 

 having a similar trend. The other fields, the Lanarkshire and Kfe and 

 Lothian basins, are more irregular, but bear out the idea that the coal- 

 basins are dispersed at intervals along the trough-valley of the Lowlands. 

 We may, therefore, reasonably expect similar basins along the south-westerly 

 continuation of this valley. Indeed, had we no further grounds for locating 

 these basins, we should have a fair degree of probability on our side if we 

 merely marked them off at regular intervals. We might thus locate one 

 under the North Channel ; a separating arch, possibly, under the eastern 

 part of Antrim; and a second, of which we see the south-western edge at 

 Dungannon and Coal Island, under Lough Neagh. 



Evidence available for locating the concealed Basins. 



There are, however, other considerations which indicate that the Lough 

 Neagh area is one of these basins. In the first place, the Lough clearly 

 occupies a synclinal basin in the Tertiary lavas and the underlying Mesozoic 

 rocks, which dip in towards it on all sides. On the principle of posthumous 

 folding, according to which the synclines and anticlines in the newer rocks 

 tend to follow along the lines of much more pronounced synclines and anti- 

 clines in the older rocks, we would be led to expect beneath the Lough a 

 synclinal basin bringing in the upper beds of the Carboniferous formation. 

 The axis of this basin runs in a S.S.E. direction along the valley of the River 

 Bann, and along the length of the Lough, towards Armagh. This axis, though it 



