““ IGNEOUS ROCKS.” 27 
UPHEAVING OF 
discrimination of those rocks of igneous origin, 
(speaking of their superficial appearance) from those 
which are not igneous, and of those connexions de- 
pendent on the application of fire, from those not 
so derived, would depend on evidences of rupture, 
or upheaving, or tilting, apparent in the vicinity ;— 
on analogy of the structures and appearances to 
those of igneous derivation in the present day ;—on 
the absence of organic relics, and on any traces of 
former volcanic condition. If our granitic tract be 
visited, it will be seen that oftentimes slate is at- 
tached to granite with considerable irregularity, it 
does not merely repose on it, but is even connected 
to it on its slopes by firm cementation, as if indeed, 
the slate, in its original position underground, had 
been blended into the spongy substance of the 
granite during its liquefaction, and then, when the 
latter rose into its mountain forms, it conveyed 
the slate so cemented with it, beyond the level of the 
bed through which it had been projected. Through- 
out the South of Devon, instances may be repeatedly 
seen, where slate has been contorted, and disturbed 
into repeated angles, where its texture was suffici- 
ently loose to admit of ready and extensive fracture; 
towards the top, good solid slate often becomes 
looser, and bent off at an angle, and possibly these 
facts are dependent on some upheaving force of the 
volcanic order. The accompanying engraving re- 
presents a remarkable case of this kind occurring in 
my neighbourhood. 
Appearances of the same kind seem to occur in 
sandstone quarries. ‘There are likewise reasons to 
believe, from phenomena presented by some local- 
ities, that trapp has upheaved and dislocated lime 
beds, and lime and slate connectedly, and in some 
places it has even gained a superior position to them. 
Prior to my belief in the Plutonic theory, I had con- 
EK 2 
