of the Counties of Derry and Antrim. lgi 
From the Black Rock to the Giant’s Causeway (about a mile) 
the materials, and their arrangement, are similar to those of 
the coast to the westward, viz. strata of table basalt, gene- 
rally separated by thinner strata of a reddish substance. 
At the Giant’s Causeway a new arrangement commences, 
one of the little systems I have mentioned in other memoirs, 
by the aggregate of which our coast is formed ; nature having 
changed her materials, or their disposition, or both, every 
two or three miles. To the system of strata comprehended 
between the Giant’s Causeway and Dunseverick I now limit 
myself, as all the strata composing it emerge between these 
two points. 
As we proceed along the coast from the Giant’s Causeway 
eastward, we perceive the whole mass of strata ascend gra- 
dually, culminate at the northern point of the promontory, 
and then descend more rapidly, as the land falls away to the 
south-east, until having traced them across the face of the 
precipice we see them immerge separately at and beyond 
Portmoon JVhyn Dykes. 
The western side of the promontory is cut down perpendi- 
cularly, by eleven JVhyn Dykes ; the intervals between them 
are unequal, but they all reach from the top of the precipice 
to the water, out of which some of them again emerge in con- 
siderable fragments ; they are all constructed of horizontal 
prisms, which are strongly contrasted with the vertical pillars 
of the strata through which they pass. 
One of the clvkes at Port Cooan, on Bengore, half a mile 
from the Giant’s Causeway , is very beautiful ; an insulated 
rock about 160 feet high, and 20 in diameter, stands per- 
pendicular in the middle of a small bay ; the main body of the 
