311 



at this spot, so that the layer may be a few feet thicker, and the 

 columns a few feet longer. Where the layer is well developed, in the 

 face of the cliff at Plaiskin, and at Bengore Head, it is not accessible 

 for measurement by line and rule to ordinary visitors, nor even in 

 favourable circumstances for trigonometrical measurement, from the 

 perpetual agitation of the ocean on this coast. 



Basaltic columns occur in many other places in Antrim besides the 

 Causeway ; but they are chiefly confined to a zone, a mile or two 

 wide along the north coast, between Ballycastle and Portrush. They 

 are to be found farther inland, but the surface is, for the most part, co- 

 vered with tillage or bog, and they are not visible. The ranges of 

 pillars are found at various heights in the hills, above the level of the 

 sea. The following Table shows the localities of the chief groups of 

 them, and the heights at which they occur in each place above sea 

 level : — 



Basaltic Pillars 



in various 



Localiti 



2. 

 3. 



4. 



4. 



6. 

 7. 

 8. 

 9. 

 10. 



11. 



12. 

 13. 

 14. 

 15. 



16. 

 17. 

 18. 

 19 

 20. 



Islandmore Upper and Crossreagh ; two ranges, one 



over the other, nearly half a mile long, running north 



and south, S± miles north-east of Coleraine, 

 Oraigahulliar, 4j miles north-east of Coleraine, . 

 Cloyfin, 3 miles north-east of Coleraine, 

 Toberdornan, or Dunmull, 5 miles north-east of Cole 



raine, . . . . 



Ballyhome and Urbalreagh, 6 miles nort-east of Cole 



raine, ........ 



Ballytober, 7 miles north-east of Coleraine, 



Boneyclassagh, i mile east of Dunluce, 



Bushmills, in the river banks at the town, 



Carnkirk, 2 miles north-east of Bushmills, 



Tonduff, one mile south of Bengore Head, and 3 miles 



north-east of Bushmills, 



Croaghmore, 5 miles east of Bushmills, and 1 mile 



south of Whitepark, ..... 

 Knocksoghey, half a mile east of Ballintoy, 

 Glenstaghey, 1 mile east of Ballintoy, 

 Craiganee, 1 mile south-east of Ballintoy, 

 Ballycastle, near the harbour, rudely columnar trap 



columns three to six feet diameter, . 

 Ballygally Head, 4 miles north of Larne, . 

 Black Head, 6 miles north-east of Carrickfergus, 

 White Head, 4 miles north-east of Carrickfergus, 

 Shane's Castle, on the north shore of Lough Neagh, 

 Mouth of Glenavy River, 13 miles west of Belfast 



near the shore of Lough Neagh, 



I shall give a few more illustrations of basaltic columns, in different 

 conditions. Fig. 8 is a view of a dyke of columnar trap, in brecciated 



Height 

 above Level. 



350 

 250 



434 



436 

 245 

 319 

 50 

 270 



300 



582 

 578 

 450 

 550 



sea. 



sea. 



210 

 80 

 60 



60 



