302 MORLEY E. WILSON 
were published, the volcanic rocks of the complex have been classed 
as Keewatin in accordance with Lawson’s nomenclature, but the 
name Laurentian has been limited to the older granite which lies 
unconformably beneath the Ogiskie conglomerate and Knife Lake 
slates, while these sediments, along with the younger granite which 
intrudes them, have been designated Lower or Lower-Middle 
Huronian. The scheme of classification worked out in the Ver- 
milion region is essentially the same as that indorsed by the Inter- 
national Committee in their report on the pre-Cambrian nomen- 
clature of the Lake Superior region’ and has been generally adopted, 
as far as practicable, by Canadian geologists engaged in geological 
work in the pre-Cambrian regions of northern Ontario and Quebec. 
But in applying this classification in the Lake Huron—Lake 
Timiskaming region, serious difficulties have been encountered, 
for the rocks known as Lower-Middle Huronian in the region north 
of Lake Superior are similar in every respect to the younger (Timis- 
kaming, etc.) series occurring in the pre-Cobalt series complex, 
whereas the name Lower-Middle Huronian implies that they are 
approximately equivalent in age to the Cobalt series and the 
original Huronian, which they resemble in no particular whatever. 
While it might be objected that the Lower-Middle Huronian rocks 
of the region north of Lake Superior are too far distant from the 
rocks composing the Timiskaming series for their correlation, yet, 
if the rocks occurring in these two regions are to be correlated at 
all, then the Lower-Middle Huronian must certainly be correlated 
with the pre-Huronian Timiskaming series, rather than with the 
Cobalt series or the original Huronian. At any rate, it is at least 
probable, from the remarkable lithological and structural similarity 
of the basal pre-Cambrian rocks occurring throughout the whole 
region from Lake Superior to Lake Timiskaming, and the evidence 
of the presence of an erosion interval in the pre-Cobalt series com- 
plex, similar to that beneath the Ogiskie conglomerate in the 
Vermilion region, that the rocks which underlie the Cobalt series 
in the Timiskaming region are the same as those beneath the 
Animikie series in the region north and west of Lake Superior and 
that the pre-Huronian paleoplain occurring in the Lake Huron—Lake 
t Jour. of Geol., XIII, 89-104, 1905. 
