348 Methods of Stratigraphy. — Winchell. 
of the Canadian survey, became current in nearly all Ameri- 
can geological literature. If we examine carefully the reports 
of the Canadian survey we fail to discover any description of 
the Huronian, as such, till after 1855. We find no section of 
the rocks on the north shore of lake Huron nor on the shores 
of lake Superior by means of which a correct idea can be 
obtained of the Huronian series until 1857,'^ yet the term 
seems to have been in current use to some extent since 1854, 
since it appears incidentally in the reports for that year, and 
for 1855. The characters of the rocks of the Huronian, as 
finally and fully published, are given in the geology of Cana- 
da, 1863, pp. 59-66, and their typical area is mapped in the 
atlas accompanying that volume. It is to this authority, 
therefore, that it is necessary to refer, and by this final presen- 
tation must the Huronian stand or fall. It is only necessary 
to say at this place what has been said by Prof. Irving and 
by others who have recently examined these strata, that they 
consist of non-crystalline rock-species — mainly conglomer- 
ates, quartzytes and slates, with some limestone, cut by and 
interbedded with eruptive rocks, mainly dolerytes and 
diorytes. It will be noticed, however, that in tHis last presen- 
tation of the Huronian an important change was made in its 
upward extension. The volcanic rocks of lake Superior are 
set off by themselves under the designation "Upper Copper- 
bearing rocks of lake Superior," and are divided into two 
groups, the lower "consisting of bluish slates or shales, inter- 
stratified with sandstones and beds of columnar trap, and the 
upper, of a succession of sandstones, limestones, indurated 
marls and conglomerates, also interstratified with trap which 
is often amygdaloidal." Of these the lower group is what was 
afterward named Animike, and the upper group is, as I have 
shown in my 17th report on the Minnesota geological survey, 
pp. 52-55, the equivalent of the upper quartzytes of the original 
Huronian and lies unconformably on the lower group. 
If we revert next to the reasons that induced Dr. Bigsb}'^ to 
remove the Huronian from parallelism with the Lower Cambrian 
we shall find a curious medley of assumption, inference from 
insufficient data, and of generalization from ill-supported 
inference. It had been argued b}^ Mr. Thomas Macfarlane in 
'* Canadian n port of progress for the years 1853-54-55-50. p. 172. 
Report for 1856. 
