[COLEMAN] CLASSIFICATION OF THE ARCHÆAN 143 
and much of the Huronian seems certain, and that they were formed 
under not unlike conditions is probable; but that the Hastings and 
Grenville series are the exact equivalents of either the lower or upper 
Huronian is uncertain, though one naturally thinks of them as formed 
during the time which elapsed between the beginning of the Coutchi- 
ching and the completion of the upper Huronian. 
THE ALGONKIAN QUESTION. 
The relationships of the rocks called by the American Geological 
Survey Algonkian with the rocks classed by Canadians as Huronian 
or Keewatin have long been in dispute, though appearances now point 
to a reconciliation between the two schools of Pre-Cambrian geology. 
The origin of the differences of opinion and of nomenclature may 
be traced to Irving’s views as to the equivalence of the Penokie iron 
range rocks with the Huronian and with the Animikie of Thunder 
bay! Logan had shown that the Animikie and also the Huronian 
cecur on the shore of Thunder bay, and Irving in his brief visit to 
the region overlooked the fact that the almost horizontal Animikie 
slates and cherts lie unconformably over the steeply tilted Huronian 
schists along the shore of the bay, and jumped to the conclusion that 
the two series of rocks are the same. Logically enough, he included 
the Vermilion iron range also, since that is in reality the south- 
westward extension of the Huronian at Thunder bay. His visit to 
the slightly tilted and not greatly metamorphosed Huronian strata 
on the north shore of Lake Huron seems to have misled him into the 
belief that the Huronian as a whole was little tilted or altered. In 
reality, instead of being equivalent, the Animikie and Huronian are 
separated by the profoundest gap known in geological history, the 
Eparchæan Interval, as Lawson has named it, and this has been recog- 
nized ever since Logan’s time in Canada and also by the Minnesota 
survey. 
The Algonkian was founded to include all Pre-Cambrian sedi- 
ments, the Fundamental complex underlying it being looked on as 
of eruptive origin. As the main defender of the classification, Pro- 
fessor Van Hise, has recently admitted that the Vermilion and Michi- 
picoton iron ranges, which are undoubtedly of sedimentary origin, 
are of pre-Algonkian age, it is evident that a rearrangement of the, 
classification and of the nomenclature is demanded.? Unfortunately, 

? U.S. Geol. Sur., 8rd An. Rep., 170, etc. 
* U.S. Geol. Sur., Iron-ore Deposits of the Lake Superior Region, 1901, 
p. 317. 
