OP THE CARBONIFEROUS SERIES. 615 



least, one important value — that they will strictly define the limits 

 of the coal -bearing tracts. 



I propose in this paper to show to what extent the British Car- 

 boniferous rocks have their representatives in Ireland ; after which 

 I will endeavour to point out the significance, as bearing on the 

 question of classification, of that remarkable series of beds already 

 referred to, known as the " Gannister Beds " of the late Professor 

 Phillips ; and lastly I shall state the conclusions which seem to me 

 to arise from the above considerations, and which seem to render 

 desirable a fresh mode of classifying the Carboniferous beds, with a 

 view to the introduction of a " Middle Carboniferous series " to in- 

 clude all the strata lying between the Mountain Limestone and the 

 Middle Coal-measures, and including the Yoredale Beds, Millstone 

 Grit, and Gannister Beds. 



Arrangement of the Subject. — In considering the subject of the 

 Carboniferous beds of Ireland, it will be desirable to divide it into 

 three portions, taking : — I. The Southern Coal-districts ; II. The 

 Northern Coal-districts ; and III. The Ballycastle Coal-district in 

 Co. Antrim, which differs from both. But before doing so it will 

 be desirable, for the sake of comparison, to state the succession of 

 the strata in the British Carboniferous districts, as now very gener- 

 ally recognized*; and for the purpose of easy reference I have 

 arranged them into stages. 



The British Carboniferous Series. 



Beds in descending Order, with Localities. 



Name of Formation. Localities. 



( Stage G-. Upper Coed-measures. — Reddish and Manchester, Stoke-on- 

 grey sandstones, breccias, and clays, with Trent, Newcastle-un- 

 thin coal-seams and limestones. der-Lyne, S. part of 

 Fossils (freshwater or estuarine). — Fish (mi- Dudley Coal-field; 

 gratory) ; Crustacea, Cythere inflata ; Anne- Banks of the Dee 

 lids, Spirorbis carbonarius. , near Euabon; Hamil- 



a 



u 

 co © 



- 

 © 



** 



fc^.3 



<3 M 



a 



© 



CO 

 GO 



ton and Ayrshire in 

 Scotland. 



Stage F. Middle Coed-measures. — Yellowish Central portions of all 



sandstones, clays, and shales, with thick the coal-fields of 



coals. England and Wales ; 



Fossils (freshwater or estuarine)t. — Fish (mi- Upper Coal-measures 



gratory) ; Molluscs, Anthracosia, Anthraco- of Scotland. 

 my a ; Crustacea, Beyrichia, Estheria ; An- 

 nelids, Spirorbis. Marine species, rare. 



* ' Coal-fields of Great Britain,' 3rd edit. p. 80. Index-sheet of formations 

 of the Geological Survey (1871). 



t Though the fossils of the Middle Coal-measures consist of those bivalves 

 above named, and of whose habitat there is some doubt, true marine bands are 

 occasionally found, as at Ashton-under-Lyne, with Discites, Aviculopecten, &c. 

 See " Geology of the Country around Oldham," Mem. Geol. Survey, p. 64. 



2s2 



