186 TRANSACTIONS OF THE [APR. 16, 
character, and are unconformable to each other and to the over- 
lying Cambrian sediments, so that they have been compared to 
the Laurentian and Huronian series of Quebec and Ontario, and 
named accordingly. 
These names are open to considerable objection when applied 
to the New Brunswick Pre-Cambrian on account of the restricted 
sense in which they are now used. Further, they are liable to 
be understood as implying a time-equivalence which is by no 
means certain, even in the former broader sense of the terms ; 
and they were replaced in the later Survey Reports by numbers 
to indicate the divisions. But as this article deals with the 
petrography rather than the stratigraphy of the country mapped, 
it seems best to retain the old and well-established names, with 
the understanding that they imply merely a convenient and 
natural division of its Pre-Cambrian strata, corresponding to 
that found elsewhere. Whether this correspondence implies 
any real equivalence, or merely a similar succession of condi- 
tions, is unproved, if indeed it be provable. Within the area 
mapped, no rocks which can well be compared with the “Archean 
complex ” are seen;* it may be present elsewhere in the proy- 
ince. As a matter of convenience, then, the terms Laurentian 
and Huronian will here be used for the two divisions of the New 
Brunswick Pre-Cambrian. 
The earlier series or Laurentian consists chiefly of granitic and 
oneissic rocks, limestones and quartzites, the two last confined 
to the upper beds. It appears to have been considered, in the 
time of the earlier reports at least, as almost all sedimentary, 
though eruptive granites are occasionally noted. The strata 
lie steeply inclined in a succession of ridges and folds with a 
general northeast and southwest direction. 
Overlying this more crystalline series, at a generally lower 
dip, are fine-grained flinty rocks, interbedded with various 
schists, porphyries, ash-rocks and sandstones, and with great 
masses and dykes of trap. These have been called Huronian, 
and with them have been coupled other rocks of similar charac- 
ter, but doubtful relations. This series has been considered as 
in part sedimentary, in part surface volcanic products, more or 
* Prof. Van Hise, in Bulletin 86, United States Geological Survey, suggests 
separating the upper (limestone) beds of the ‘‘ Laurentian ”’ of New Brunswick, 
from the lower (gneiss) and calling the latter, Archean, while the former is 
added to the Algonkian. But in the neighborhood of St. John, the first de- 
scribed and typical area of the southern New Brunswick rocks, the true 
gneisses are conformable with, and in their upper part interbedded with, the 
limestones and quartzites, while the Jatter are unconformably overlain by the 
voleanie clastic “‘Huronian” group. The unconformity between the upper 
and lower * Laurentian ” described in the early reports isan intrusion contact ; 
aside from these intrusives, the gneisses are closely connected with the lime- 
stones. 
