Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/181



Many more examples of this very interesting fact would, there is little doubt, be found on further examination; but those cited are sufficient to prove that it is not unfrequent.

On the shore, a little to the west of the pier of Ballycastle, a singular vein occurs in the chalk, which there forms the inferior portion of a chalk capped with basalt; the basalt immediately incumbent on the chalk approaches to the character of wacke. The vein in question is calcareous, but contains imbedded balls of wacke; to the presence of which the difference of its characters from those of the chalk that it traverses, may perhaps be attributed. The limestone forming the vein is compact, breaking spontaneously into parallelepipeds, the greater side of which is perpendicular to the direction of the vein; it contains about nine-tenths of calcareous matter, the residuum appearing to be clay, with some specks of bright mica. The width of the vein is 17 feet; its direction N.E. S.W. 33°.

Near the top of the stratum of chalk which crowns the cliffs of Murloch bay, a bed five or six feet thick, of wacke approaching to basalt, occurs interstratified with the chalk in a conformable position.

I shall now proceed to trace the outgoing of the chalk round the basaltic area, beginning in the south-eastern quarter, and pursuing it to the south-western, inserting in parallel columns the names of places observed in the order of their succession along this route, and the observations I had an opportunity of making concerning the dip of the strata, the elevation of the formation, &c.