OF THE CAKBONIFEROUS 8EEIES. (125 



The Gannister Beds are of unusual but unknown thickness ; they 

 occupy a considerable tract between Drumglas Colliery and Coal 

 island, and, though only partially explored, have been proved to 

 contain some of the marine Mollusca characteristic of stage E. Thus 

 over the Crenagh coal Lingula squamosa occurs in considerable 

 numbers associated with Orthoceras, Bellerophon, and Productus. 

 Just above " the Drumglas coal " Lingula occurs abundantly, and in 

 beds 200 yards higher up Goniatites *. 



3. The Bally castle Coal-field, Co. Antrim (Lower Carboniferous). — 

 This is the last of the Irish coal-fields requiring our attention ; and 

 it stands alone in geological position, for there can be little doubt 

 that it is the representative of the " Lower Coal-fields " of Scotland, 

 and, like them, of the age of the Yoredale Beds and Carboniferous 

 Limestone. It has been the subject of several memoirs by Bergerf , 

 BryceJ, and Griffith §, the last of whom gives a very elaborate account 

 of the remarkable features of this district. While making, in 1869, 

 a rapid survey of this coal-field in order to arrive at some approxi- 

 mate estimate of its resources for the Eoyal Coal-Commission, I was 

 so struck by the general resemblance of the beds to those which 

 form the Lower Coal-field of the Clyde basin, that I came to the 

 conclusion that they also were of Lower-Carboniferous age, a con- 

 clusion confirmed by the evidence of the fossils ||. 



General Section. 



The general section seems to be divisible into two, possibly three, 

 stages, corresponding to stages A, B, and possibly C of the classifica- 

 tion here adopted, and is as follows i[ : — 



Upper Beds. Stage C. — Reddish and grey sandstones, shales with 

 seams of coal, clay-band and black-band ironstone. Lingula 

 squamiformis (Phil.), Sagenaria imbricata, Sigillaria, &c. 



Middle Beds. Stage B. — Compact argillaceous limestone in two thin 

 beds with shales. Fish, Orthoceras Steinhaueri, Bellerophon Urii, 

 Murchisonia angulata, Leda attenuata, Bhynchonella pleurodon, 

 Productus giganteus, &c. 



Lower Beds. Stage A. — Red and yellow sandstones, sometimes coarse, 

 with shales and black-band ironstone ; conglomerate at base (Mur- 

 loch Bay). 



(The entire thickness exceeds 1200 feet). 



* Information supplied by Mr. Hardman. 



t Trans. Geol. Soc. Lond. ser. 1, vol. iii. 



\ Ibid. ser. 2, vol. v. 



§ ' Geological and Mining Survey,' Dublin, 1829. 



|| The fossils have been determined by Mr. W. H. Baily, and are given in 

 my paper "On the Geological Age of the Ballycastle Coal-field," Journ. Geol. 

 Soc. Ireland, vol. i. New Series, 1871. 



1" 'Coal-fields of Great Britain,' p. 314 (1873). 



