BOULDER IN (PRIMITIVE ?) SLATE. 23 
deposition of the other series, and moreover as Mr. 
de la Beche observes, the detrital matter of such 
primitive rocks, may be found blended into the 
composition of those strata which happened to re- 
pose on them, and which, during their precipitation, 
would acquire this foreign material, just as if the 
former had been upheaved and affected the latter 
in the more usual manner. 
That apart at least, of those rocks which unfil 
lately had by common consent been accounted pri- 
mitive, are really entitled to that primeval rank, 
we are fortunately enabled to demonstrate. Be the 
period of “ granitic intrusion” what it may, it can 
be shewn that granite had priority of existence to 
those strata which suffered at some time from its 
upheaving, and that even some trivial difference 
probably existed between the characters of those 
two granite rocks, in regard of the size of the com- 
ponent chrystals. In this district and in the 
neighbourhood of the granite range, enclosed or 
rather impacted in slate, a few feet below the sur- 
face, was found an oblong and highly rolled granitic 
pebble, fine grained, and of the size of two fists. 
Now, the knowledge of this circumstance (for the 
relation of which I am indebted to Capt. Blanckley, 
who witnessed its removal and presented it to the 
Natural HistorySociety)is doubly valuable, because, 
it proves not only the primitive character of granite 
as a rock, or at least its priority to schist, but also, 
that at the period of slate being called into osten- 
sibility as a rock, the operative element acted most 
_ forcibly, both in its production and in its casual 
- effects on the previously existing stratum.. From 
the locality above named, there is reason to suppose 
that this boulder occurred in what geologists are 
pleased to term “ primitive slate,” and if so, it will 
be requisite to remind them, that, coevality of occur- 
rence can no longer be claimed for these two strata, 
