10 



THE GEOLOGIST. 



In the cliffs to the south of Poii:noffer, adjoining the Causeway, 

 •Nvhich average from two hundred and seventy feet to thi^ee hundred 

 and seven feet in elevation (fig. 6), the two columnar beds, which 



Lign. 6.— CUffs South of Portnoffer. 



Lign. 7.— The Wliiii Dyke. 



are so distinct at the summit of the " Chimney-" headland, are repre- 

 sented by not less than possibly fom- separate deposits of trap ; the 



