UPHEAVING OF “ IGNEOUS ROCKS.” 25 
in caverns, and under certain peculiar circumstan¬ 
ces, both in these caves and without , hereafter to 
be described. 
On6 kind of boulder may here be more especially 
named, as involving doubt and theory as to its origin. 
In the slate of the coast, certain spots attract notice, 
from containing knobs of harder material, and 
seemingly of the description of sandstone (which 
moreover, is abundantly joined in every variety of 
way to our slate) ; these knobs are rounded, and in 
some measure, placed in parallel lines, thereby in¬ 
ducing the conclusion of their being rounded, and 
involved in the substance of the slate during its 
deposit. 
The truth of these new ideas of the modern eleva¬ 
tion, or intrusion of granite, trapp, &c. seems to be 
continually borne out by every fresh examination of 
primary rocks in all the modifications and relations 
they assume, and the convenience of the theory for 
reconciling facts of a seemingly opposed character, 
is strongly manifested by attention to the very inter¬ 
esting and instructive geology of this county. It is 
contended then, by the new theorists, that a great ma¬ 
ny of our rocks, of which it will suffice here to name 
those principally meant,—granite, trapp, porphyry, 
schorl, serpentine and gneiss, are so far as respects 
their superficial appearance, of posterior date to all 
our others; they have, through the agency of fire, been 
reduced to a softened state and then forced up, and 
disseminated in some measure, around and between 
the beds of those rocks against which they happened 
to impinge, and whether in their fluid form, or in 
their cooled and hardened state, have been forcibly 
driven up, and have extensively dislocated those 
strata, under which they were situated. Occasionally 
indeed, no particular disturbance can be detected; 
trapp for instance, lies parallel with limestone, and 
sandstone in some situations, without any appear- 
E 
