Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/148



The strata are alternately coarsely and finely slaty: the thickness of the whole mass may be rated at fifty feet. Veins of calcareous spar intervene as seams between the individual strata.

At Toberbilly, on the north-west side of Knocklead, near Ballycastle, at an elevation of four hundred and ninety-four feet above the level of the sea, I traced a bed of granular and micaceous limestone through a considerable extent towards the town-land of Cloughamany.

The concretions are rather small, and there are linings of talc along the seams of stratification.

The remark of Werner, that primitive trap contains no iron clay, but is wholly or almost entirely composed of hornblende, appears to be extremely appropriate, and to draw an excellent line of demarcation between primitive and the secondary trap.

More than two-thirds of the Foy mountain, near Carlingford, are composed of a succession of stairs formed of primitive trap.

Proceeding from the bottom towards the summit of that mountain,