of the Counties of Derry and Antrim. 
205 
Inquiry into the Formation of our perpendicular Facades. 
It is natural that the first great operation we proceed to in- 
vestigate, should be the formation of our magnificent fayades, 
one of which is the principal subject of this memoir. 
The line of coast that bounds our basaltic area on its north 
side, extends about twenty- five Irish miles, in which course 
the precipices are nearly continuous, and more than one half 
of them absolutely perpendicular for a great part of their 
stupendous height. The operation by which they were cut off 
so abruptly, and left with a formidable aspect towering over 
our coast, is the one we inquire into. 
That these bold precipices once projected farther in many 
places is easily demonstrated ; at Beany n Daana, and at the 
Chimney , the columnar construction was obviously once carried 
much farther out. 
At the Milestone , Portcooan, and Portnabau, the fragments 
of dykes extend far beyond the face of the precipice. 
These same facts, together with the projecting base, shew 
that these sudden abruptions were not formed by the subsid- 
ing, and sinking of one part, leaving the remainder in its 
place : still less by any violent revolution, or convulsion ; as 
the stratification has not sustained the slightest shock either 
above, or below the facade. 
The formation of our abrupt coast, has been ascribed to 
the action of the sea beating violently against it, washing 
away the lower parts, and leaving a perpendicular facade 
standing ; as we often see on the banks of rapid and en- 
croaching rivers. 
A cool examination of our precipices will soon prove that 
