20 9 
of the Counties of Derry and Antrim . 
direction must have been the result of a disturbing cause 
acting from below ; whereas parallelism and a steady recti- 
lineal course distinguish the basaltic arrangements of which 
I have been treating. 
We have, it is true, occasional depressions of our strata, 
where they obviously have subsided, and no doubt from a 
failure of support below ; but in no instance that I have met 
with, in our area, are these attended by the slightest concus- 
sion; the permanent and subsided parts, with us still preserve 
their parallelism, and the continuity of their material; whence 
it is probable this event took place previous to the induration 
of the strata, and of course antecedent to the period to which 
I limit myself. 
Buffon ascribes our superficial inequalities to the agitation 
of the waters while they covered our earth, and argues from 
the resemblance these inequalities bear to the waves of the 
sea ; a resemblance I cannot trace in any country which I have 
observed ; nor could our sudden and perpendicular abruptions, 
ever have been produced by any agitation of the waters. 
Professor Playfair considers rivers as having formed not 
only the beds, or channels in which they flow’, but also the 
whole of the vallies through which they run, and in general 
all the inequalities of our surface ; but an attentive observer, 
tracing the course of any of our most rapid rivers, would soon 
perceive that the quantity of its depredations have been com- 
paratively insignificant, and that they can be determined with 
precision ; the river has no doubt in several places extended 
itself considerably on both sides, but in the intermediate space 
between the remotest boundaries it ever reached, it levels, 
instead of raising inequalities. 
E e 
MDCCCVIII. 
