5*26 Scientific Proceedings, Royal Dublin Society. 



Slievebeagh district must, at least in part, represent the Lower 

 Coal-measures, although they are so different lithologically from 

 those of the Tyrone Coal-field to the eastward. 



But it must be remembered, as pointed out in my Geology 

 of Ireland (1878), that in the Coal-measures of North Con- 

 naught there is a marked change, the lithological characters 

 -of the Lower Measures being very different to those elsewhere 

 in Ireland ;■ as below, immediately above the Upper Limestone, 

 a more or less thick group of sandstones appear, with subordinate 

 argillaceous and calcareous strata ; while in the Middle Measures 

 there are three coals, one of value. In Tyrone also, but not else- 

 where, are found workable coals in the Middle Measures. 



In North Ulster there are other peculiarities, as the rocks 

 appear to have accumulated in bays or seas of limited extent ; and 

 the different groups of rocks, elsewhere capable of being separated, 

 become mixed up ; the red and yellow sandstones, the different 

 types of limestone, and even shales, identical, except in fossils, 

 with those of the Coal-measures, being more or less mixed up. 

 These rocks, which may be called the Ulster Calp type, occur 

 nearly altogether north of a line drawn from Lower Lough Erne 

 along the Silurians of the Pintona district to Lough Neagh, 

 excepting the rocks near Cookstown, Co. Tyrone, which are south 

 of this line, and have some characteristics allied to those of the 

 " Ulster Calp type." 



The upper group, or the Coal-measures, has, as Lower 

 Measures in East Ulster, some five hundred to seven hundred 

 feet thickness of shale, over which, in the Middle Measures, are- 

 naceous rocks predominate, while in the Upper Measures there is 

 a mixture of arenaceous and argillaceous rocks, with coal. But in 

 North Connaught, and the adjoining part of Ulster, there are im- 

 mediately above the upper limestone more or less arenaceous strata, 

 &nd above these shales, and these combined represent the Lower 

 Measures. Above these are the Middle Measures, which are for the 

 most part arenaceous, but having in them workable coals. In 

 Eastern Ulster (Tyrone), although the strata of the Coal-measures 

 occur in a very similar arrangement to those of Leinster and 

 Munster fields ; yet in the Middle Measures there are valuabl 

 •coals. 



At the present time the Coal-measures Sandstone of Ireland, 



