614 EDWARD HULL ON THE CLASSIFICATION 



been able to ascertain, the term "Coal-measures" has come to be 

 applied to all the beds from the top of the Limestone up to the 

 coal-bearing* measures of the Leinster Coal-field and of the corre- 

 sponding beds of Kerry, Limerick, and Clare. The consequence is 

 that it has sometimes been supposed that the coal-bearing districts 

 of the south of Ireland are much more extensive than is actually the 

 case. As far as the maps of the Geological Survey are concerned, 

 we are now taking steps to give to the public a truer idea of the 

 actual limits of the coal-bearing strata, and also to correlate with 

 the British series the strata between them and the Limestone. Mr. 

 Hardman has nearly completed a resurvey of the coal-districts of 

 Carlow, Kilkenny, and Tipperary, resulting in a more accurate and 

 detailed representation of the different divisions ; and I hope a simi- 

 lar revision will ultimately be extended to that large area in the 

 south-west occupied by similar beds, with very little true Coal- 

 measures at all, but which has been described only recently as " one 

 of the largest coal-fields in the British Islands." 



Notwithstanding that the term " Coal-measures " has been ap- 

 plied to all the beds above alluded to in the publications of the 

 Geological Survey as well as of amateur geologists, the late Director 

 of the Irish Survey, Professor Jukes, has left on record his opinion 

 that the lower portion of them, including the shales and flags im- 

 mediately over the Limestone, are in reality the representatives of 

 the Millstone- Grit series of England. Thus, in the Explanatory 

 Memoir to sheet 137 of the maps of the Geological Survey, he says : — 

 " Doubtless the whole of the Coal-measure series of Central Ire- 

 land is contemporaneous with the lower part only of that of Central 

 England, including the Millstone Grit in that lower part."* 



I have reason to believe, from a conversation I have had with the 

 father of Irish geology himself, Sir E. Griffith, that he shares the 

 same opinion ; and if there had been room for doubt on the subject 

 on other grounds, this doubt must have been dispelled upon the 

 identification in the Leinster Coal-field of that peculiar and impor- 

 tant member of the Carboniferous series, namely the " Lower Coal- 

 measures " or " Gannister Beds," f which, in the north of England, 

 overlies the Millstone Grit, and contains the expiring representatives 

 of the marine fauna of the Lower Carboniferous series as hitherto 

 constituted. 



The additions which are now being made to the maps of the 

 Geological Survey of the Leinster and Minister coal-fields will be at 

 once understood when it is stated that instead of one formation, re- 

 presented by one shade of dark colour, and included under the 

 general term of " Coal-measures," we are tracing out and distinguish- 

 ing representatives of four divisions, viz. : — 1. Yoredale Beds ; 2. 

 Millstone Grit; 3. Gannister Beds ; and 4. the Middle Coal-mea- 

 sures of the British series. The changes thus effected will have, at 



* L.c. p. 11, foot-note. 



t In the succeeding pages I shall call this member of the series by ibe designa- 

 tion of " Gannister Beds," in order, amongst other reasons which will appear 

 further on, to avoid confusion. 



