The shell limestone of Desartmartin re-appears two miles farther to the north-east at Dromore, the strata preserving the same dip, direction and characters: the quarries of Dromore are more extensive than those of Desartmartin.
At Gore Tarminey in the parish of Kilcronaghan not far from Dromore, the shell limestone shows itself again, but under the character of swine stone: it is variegated, and contains terebratula gigantea. The strata dip at an angle of 12°.
At the coal works of Ballycastle two English miles north of the town, strata of shell limestone are to be seen on the shore, and may be traced at low water running out to sea in their line of bearing, which is N.E. 17°. they dip therefore to S.E. 73°.
The strata are alternately solid and marly, the former constituting beds of three or four feet in thickness, the latter not exceeding half a foot. The solid strata are of a compact limestone with lamellar and rhombic concretions, the colour smoke grey.
I have examined several specimens of a variety of this limestone containing ramose madrepores, said to have been found on the west side of Lough Neagh in Tyrone.
B. Coal Formations.
I have to notice four partial coal formations; they occur in the following counties.
- I. Tyrone: at Coal-island and Dungannon.
- II. Antrim: near Ballycastle.
1. Two Coal fields, as coal formations are usually styled in England, exist in the county of Tyrone, at no great distance the
