297 



There must thus have been a succession of such eruptions until the 

 fifteen or sixteen hard beds, with the alternating soft ones, were ac- 

 cumulated, which form the mural cliff above the road at Garron Point, 

 which is one of the many picturesque features on the Antrim coast. 



Those layers appear to have been laid down in the bottom of the 

 sea or ocean ; and the whole of that bottom afterwards raised up to- 

 gether, by subterranean power, to the position in which we now see 

 it, where the top of the mass is 760 feet above the level of the same 

 ocean in which it was deposited. 



PL XXIY. represents Bengore Head, on the north coast of An- 

 trim, id ear the Giant's Causeway. It shows layers of amorphous and 

 columnar trap, as well as a few of red ochre, alternating with them, 

 which are visible in that headland, and which dive into the water to 

 the east of it at Portmoon. The view at this place, with its alternat- 

 ing black and red layers, is analogous to that at Garron Point ; but at 

 Bengore Head there are two great layers of columnar trap, of which 

 there is none at the former place. 



The measurements of the layers at Bengore head are as follow, and 

 may be interesting. They are from a paper by Dr. Richardson, in 

 " Phil. Trans.," 1808; the numbers correspond to those on PL XXIV. :— 



j . Feet. 

 2* j Three thick layers of black, tabular, amorphous basalt, 1 ^ 

 g' J occasionally containing zeolite, . . . . J 



\ Several layers of black tabular basalt, divided by thin T 

 g' ^ seams of ochre, . . . . . . . J 



7. Bole or red ochre, . . . . . . . 22 



8. Columnar basalt, the stratum which, at its west end, 



forms the Causeway where it dips into the sea, . 44 



9. Irregularly prismatic basalt, with red ochre and brec- 



ciated trap ; in this bed the wacke and wood coal, 



or lignite of Port Noffer, occur, . . . 54 



10. Columnar basalt, the upper range of pillars at Ben- 



gore, rather coarsely articulated, . . . . 54 

 Prom the top of Bengore head, going eastward, 

 other layers crop out, as follow : — 



11. Coarsely columnar basalt, . . . . . 10 



12. Intermediate between bole and basalt, ... 8 



13. Columnar basalt begins near Berryaduna Isles, east 



of Bengore Head, . . . * . . . 7 



14. Basalt irregularly prismatic, by Dunseverick, . . 60 



1 5. Bed ochre, or bole, . . . . . . . 9 



16. Basalt, irregularly prismatic, . . . . 60 



Total, . 488 



I give these views to show that those hard layers of black rock, 

 alternating with soft layers of red rock here, are suggestive of the 



