304 MORLEY E. WILSON 
senting the facts. And since there is a series of rocks in the older 
complex north of Lake Superior classed as Lower-Middle Huronian, 
it has evidently been assumed that it is the equivalent of the Lower 
and Middle Huronian occurring to the south of Lake Superior. 
Accordingly, by comparing the Huronians of the two regions, we 
can ascertain on what facts their correlation has been based. 
1. The Huronian rocks of the southern area are largely quartz- 
ites, limestones, dolomites, and slates, while those of the northern 
area consist for the most part of conglomerate slate and mica 
schist. Their correlation has therefore not been based on the 
similarity of their lithological character. 
2. The Huronian of the north is intruded by batholiths of 
granite and gneiss; that of the south is not so intruded. It is also 
evident therefore that their correlation cannot be attributed to 
any similarity in their relationships to igneous intrusions. 
3. The northern Huronian has not only been more highly 
folded and deformed than the southern, but the deformation 
occurred at a much earlier period in the north than in the south, 
for the Animikie rocks of the north are not only almost flat-lying, 
but they rest on a peneplained surface, so that the deformation 
in the underlying complex was complete long before the Animikie 
sediments were laid down. To the south of Lake Superior, on the 
other hand, the Animikie and Keweenawan rocks are highly folded, 
and hence, if the Animikie and Keweenawan deformation were 
eliminated throughout the whole Lake Superior region, the southern 
Huronian would be but slightly disturbed, whereas that of the 
north would be just as much folded and deformed as at present. 
It is again apparent therefore, that the northern Lower-Middle 
Huronian has not been correlated with that of the south, on the 
grounds that both have been folded and deformed to the same 
degree or at the same time. 
4. The Huronian to the south of Lake Superior like that to the 
north, rests unconformably on the surface of a complex composed 
of greenstone, greenschist and iron formation (Keewatin) intruded 
by granite and gneiss, so that the stratigraphical relations of the 
Huronians in both localities are apparently the same; and it was 
evidently upon this fact that their correlation was based, but in 
