COAL 827 



' Although the carboniferous limestone extends over the greater part of Ireland, and 

 wo may assume that the coal-bearing strata of the carboniferous formation may also, 

 at one time, have exhibited a considerable extension in that country, there is, however, 

 very little of it remaining, in consequence of the subsequent denudation observable 

 there. In the south of Ireland the carboniferous limestone is accompanied by a series 

 of black shales or grey sandstone, and arenaceous or sandy shales, which contain thin 

 beds of anthracite coal in the upper strata. Professor J. Beete Jukes, who is at the 

 head of the Geological Survey of Ireland (since deceased), distinguishes in this 

 district (Castlecomer, Queen's County) the following groups of the carboniferous 

 formation, from the lower to the upper : 1. Carboniferous limestone, 3,000 feet thick. 

 2. Black shale, with occasional thin beds of sandstone, about 8,000 feet thick. In 

 these occur the fossil shells, Aviculopecten papyraceus, Posidonomya Becheri, Goniatites 

 sphfsricus, Orthoceras Stdnhaueri, and other marine animals, indicative of a lower 

 horizon. 3. Greenish-grey sandy shale, and black shale (flagstone series) charac- 

 terised by vermicular impressions or markings, which have been referred to worm- 

 tracks, as well as crustacean and molluscous tracks, 500 feet thick. 4. Black 

 shales and grey sandstone, with thin beds of coal, 1,800 feet thick ; making a total 

 maximum thickness of coal-measure strata above the carboniferous limestone of 

 3,100 feet. 



' An extensive working is carried on in the Castlecomer coal-field, which lies on the 

 borders of Kilkenny and Queen's Counties. Accurate sections referring to this field, 

 for which we are indebted to Professor Jukes, exhibit in this district five beds of coal, 

 of which, however, the upper only are observable, and that over a very limited area, 

 in consequence of denudation (probably from sea action upon what was once the coast- 

 line). The richer deposits of coal in the lower beds are found north-east of Castlecomer, 

 where, at the Garrow Colliery, at the time of my visit, a coal-bearing seam, 3 ft. 10 ins. 

 thick, was working, which yielded excellent anthracite coal, the normal Kilkenny coal 

 of Werner. The circumstances just described are perfectly analogous to those in the 

 neighbouring Geneva Colliery. Opinions still vary as to whether this Garrow bed is 

 the second or third from the bottom. At all events, it is the most important in the 

 district. In the small Leinster coal-field, somewhat further to the north-east, in the 

 direction from Castlecomer to Athy, a seam is" also worked from 18 to 20 inches thick 

 only. The numerous remains of plants collected in this coal-district, compared with 

 those of other coal-basins, show that the anthracite coal does not belong to the zone 

 (horizon) of the culm, or our first zone, but rather to the commencement of the second, 

 or Sigttlaria zone. Marine shells occur over the Garrow seam, among which the 

 characteristic and widely-distributed coal-measure fossils before mentioned, Aviculo- 

 pccten papyraceus and Posidonomya Becheri are most frequent. Numerous well-pre- 

 served bivalve shells occur, Anthracosia, Myalina, &c., locally called " beams " by the 

 miners, together with some remarkable Crustacea of the genus Belinurus, from the 

 black shales of Bilboa Colliery, situated about six miles S. W. of Carlow, the coal of 

 which is believed to correspond with the second seam of the Castlecomer district. At 

 this colliery, also, the well-known fossil plants Alethopteris lonchitidis and Sagenaria 

 elegans, were easily recognisable, two forms, which, in the productive coal-formation 

 of England especially, have the widest distribution. In the north of Ireland, where 

 coal-bearing beds occur, in the counties of Leitrim, Fermanagh, as well as at Dungan- 

 non, in Tyrone, and Ballycastle, in Antrim, they rest upon a thick sandstone formation, 

 apparently representing the millstone grit which, separates them from the carboni- 

 ferous limestone group. Sir Richard Griffiths, Bart., in his geological map of Ireland, 

 divides the latter into an upper and lower limestone, between which the " calp " is 

 deposited, consisting of shales and sandstones, and often more than 1,000 feet thick. 

 It is remarkable that while in the whole of the south of Ireland the typical anthracite 

 or Kilkenny coal predominates, in the north the prevailing deposits are bituminous, 

 or good gas-coal. According to the investigations of Sir E. Griffiths, the coal-field of 

 Dungannon, in Tyrone, is divided into two districts, which are distinguished as the 

 Coal Island district and the Annaghone district. The first is six miles long, with a 

 mean breadth of about two miles ; the latter is only one mile long and half a mile 

 broad. In this important coal-field there are eight beds of coal, of variable thickness, 

 from 2 ft. 2 in. to 1 ft. 9 in. viz., the Annagher coal. Under these there are also two or 

 three other seams known. These coals are, for the most part, of good quality. The 

 occurrence of the productive coal-formation at Ballycastle, on the northern coast of 

 Ireland, in the county of Antrim, is very interesting, where it extends, from Fair 

 Head, in a westerly and southerly direction, to a distance of about four miles, with a 

 mean breadth of one mile and a half. It contains, at Murlough Bay, six coal seams, 

 from one to eight feet thick, of which four yield good gas-coal, while the two deepest 

 are anthracite. The first four occur between two columnar isolated basaltic masses, 

 while the two lower anthracite scams arc almost in direct contact with the lower 



