of the North of Ireland. 173 



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 cliif capped with basalt ; the basalt immediately in- 

 curnbent 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 cal- 

 careous 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.Vv^ 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. ' 



