192 TRANSACTIONS OF THE [apr. 15, 
been taken by others; while neither has any satisfactory con- 
tact of the two formations been observed, nor an instance in 
which the conglomerates of the one are unquestionably made up 
of material derived from the other.” * 
Collections made during the past three summers and studied 
by the aid of the microscope have amply confirmed the views 
held as to the volcanic origin of the greater part of the 
“Huronian.” It will be seen that a considerable variety of 
igneous rocks is represented, including lavas and ash rocks once 
precisely like those of modern times and not greatly altered by 
metamorphism. Many of the fine grained felsites and much of 
the petrosilex, however, cannot be certainly determined, even 
with the aid of thin sections; but judging from the almost com- 
plete absence among them of distinctly recognizable sediments, 
it is probable that the greater part of the doubtful ones should 
be considered as altered ashes or tuffs. 
The pre-Cambrian of Southern New Brunswick falls naturally 
into two great divisions: a lower one composed of gneisses, lime- 
stones, quartzites and various schistose rocks, usually highly 
crystalline, but of distinctly sedimentary character; and an 
upper one composed chiefly of volcanic products, fading out 
above into more normal sedimentary beds which are as a rule 
much less altered than those of the lower series. The lower 
group has been compared to the Laurentian; the upper has been 
called Huronian; but both these names are dropped in the later 
Survey Reports and replaced by numbers for the different 
groups. In the present paper they may be occasionally used as 
indicating this two-fold division, but not implying any correla- 
tion in the present restricted sense of the terms. 
The Laurentian series includes divisions 1 and 2 of the later 
reports; the first being granitic gneiss and granite, which is, near 
St. John at least, intrusive in Division 2, and may be placed 
provisionally between it and the volcanic series. Division 2 is 
clearly sedimentary, and shows a varying amount of regional 
metamorphism, being at times comparatively little altered. 
The upper series or ‘ Huronian”’ includes at least three sub- 
groups. These are: 
1. Coldbrook (Div. 3). This is composed almost entirely of 
voleanie rocks—lavas, ashes and tuffs. The most abundant 
types of rock are felsites and “ petrosilex ” (fine-grained, flinty 
quartz-felsite), often porphyritic and accompanied by much ag- 
glomerate and finer grained ash-rocks into which they seem to 
grade. Dr. Bailey also mentions various sedimentary rocks from 
* Loc. cit., p. 5. 
