Mineralogy and Geology of Nova Scotia. 301 
of no other than bivalves, and of those belonging exclusively to 
the genus anomia. This however is the fact so far as we have 
examined it. Like many substitutions of this character, they 
exhibit with great precision and beauty the original external fig- 
ure of the living shells. The slate also, when in immediate 
contact with the ore, exhibits the same remains, and it is not un- 
usual to find one half of a shell moulded in it, while the other is 
firmly attached to the ore, which is thus proved to have been 
of nearly contemporaneous origin with that rock; or at least, 
by its union with it, itis proved to have been deposited before 
the latter had entirely consolidated, or while it was yet in a plas- 
tic state. In no other way can this union be satisfactorily ex- 
plained ; for it disproves at once any hypothesis founded on the 
supposed greater antiquity of the slate, according to which the 
two bodies should lie only in contact, without showing any marks 
of intimate union. That they are nearly contemporaneous, we 
have besides the further evidence derived from the fact, that the 
fossil shells are precisely the same in both. Their more intimate 
union, in some parts, we doubt not, may have been assisted by 
the heat attending the production of the neighbouring trap rocks, 
the effects of which, we think, are very apparent in another part 
of this ore-bed, where it very nearly approaches the trap. But 
of this subject, involving again the igneous origin of the trap, we 
shall presently speak more at large. 
On ascending the highlands south of the falls on Nictau River, 
a rock was observed of a granular structure, of a greenish-grey 
color, and containing imbedded concretions of white felspar. It 
is evidently a part of a dyke of porphyry, as we have represented 
it on the map, intercepting the strata of slate and the ore-bed 
accompanying it, both of which it must cross nearly at right an- 
71 
