Methods of Strath f rap} ly. — Winchell. 858 
the Tliessalon and Missasaugui rivers. The fact is, "there 
must be a beginning and an ending, a top and a bottom," as 
Dr. Bell insists, and the bottom is placed by Logan so far west 
that this schist is not included. The fact that he has includ- 
ed it in his map of 1863 (which was really constructed in 1865) 
has no force except such as would also include some Lauren- 
tian in the Huronian, since his map of 1855 actually does cov- 
er the belt of Laurentian mentioned. 
The usage and understanding of the Canadian survey 
at the present time should he accepted as sufficient authority 
as to what the Huronian really is. The geologists of the rest 
of the world will hardly hold their mouths shut when they 
find the Canadian survey of 1855-63, contradicted by the Can- 
adian survey of 1888, and when the question involved is so 
closely connected with their own work. The principles of sci- 
ence are not to be determined by authority. 
7. The gradual stratigraphic passage from one formation 
to another, even in the entire absence of fossils, is a letter 
place to separate hetween them, than at the point where a phys- 
ical hreak occurs, because of the greater "convenience of de- 
scription and classification of our facts." (p. 7.) The simple 
statement of this argument is sufficient to refute it. 
8. It is not necessary that all Huronian rocks should he 
the equivalents of the "'tyj)e seriesT described by Logan and 
Murray^ as claimed by Prof Irving. Here we difier as wide- 
ly as the poles, for we think that quality of equivalence is the 
cardinal criterion to judge by. 
9. The resti'iction of the Huronian. as proposed is con- 
trary to the view of its founder. On the contrary it is evident 
to any one who examines the original authorities, that its lim- 
itation downward, at the lower Slate Conglomerate (or with 
the lower gray quartzyte) was in accordance with the views of 
its founders. Finally : 
10. Tlie preponderance of rocks of volcanic origin in the 
'"'' Huronian''^ is a character that is found to mark it every- 
where, indicating that an era of volcanic outbursts seta 
it off from the Laurentian. This fact is true of the Huron- 
ian as expanded, but it is not of the Huronian of Logan and 
Murray, which consists of conglomerates, quartzytes and lime- 
stones, in the proportion of 18,000 feet to 5,000 feet of diabase 
and dioryte, the latter not being worked over bv sedimenta- 
