190 Dr. Richardson’s Letter on the basaltic Surface 
deflects to the S. S. E. and near the old castle of Dunseverick, 
resumes its former rectilineal and nearly eastern direction. 
The promontory occupies the interval between Dunseve- 
rick, and the Black Rock , at the end of Bushfoot Strand, about 
four English miles ; the facades commence at Black Rock, 
and increase in height until we reacli Pleskin, where the per- 
pendicular part at the summit is 170 feet, and the precipitous 
part from the bottom of the pillars to the sea 200. As we 
proceed on from Pleskin to Dunseverick, the height gradually 
abates, and is finally reduced to about 100 feet. 
In this whole space, wherever the precipice is accurately 
perpendicular, the several strata are easily distinguished from 
each other, but where the slightest obliquity prevails, a grassy 
covering is formed that effectually conceals all beneath it ; 
hence the face of the precipice seems much diversified; 
the columnar strata in some places only exhibiting detached 
groups of pillars, while in others they form extensive colon- 
nades. 
I shall now state the appearances as we approach, and coast 
the promontory from the westward, noticing in this first view 
of the precipice, every thing that may be considered as gene- 
ral, and reserving ( as I did with you ) for my return in the con- 
trary direction, a detailed account of the strata taken sepa- 
rately. 
The first circumstance, that occurs to the attentive ob- 
server on his approach, is, that although both the promon- 
tory itself, and the strata composing it, ascend to the north- 
ward, yet it is not in the same angle, the strata being more 
inclined to the horizon than the line tracing the surface 
of the promontory, a fact which I shall account for afterwards. 
