[COLEMAN] CLASSIFICATION OF THE ARCHÆAN 145 
lower Huronian, and also between the upper and lower Keewatin was 
made clear, it became necessary to recognize this in the classification ; 
and the Bureau of Mines of Ontario has adopted the following 
arrangement for the Archean in the Michipicoton iron region!: 
LAURENTIAN—Gneisses and granites. 
UPPER HURONIAN—Basal conglomerate. 
Iron range rocks. 
HURONIAN— | 
PURÉE) AUEON \Tuffs and eruptives. 
If this classification is to be extended to cover the Archean 
generally, the Eparchæan Interval should come above the Laurentian, 
and above that should be placed the Animikie and Keweenawan. 
Lawson in his last paper on the Archean gives a more elaborate 
scheme of classification for the Lake Superior region.? 
CAMBRIAN (upper division or Potsdam only). 
Unconformity. 
Keweenawan 
ALcoNKIAN—4 Unconformity. 
Animikie = Penokee = Upper Marquette. 
PALÆOZOIC 
Eparchæan Interval. 
HURONIAN = Upper Keewatin = Lower Marquette, etc. 
Unconformity. 
LAURENTIAN, so called, granite gneisses, etc., ‘intrusive in the Onta- 
rian) and the Carltonian anorthosites. 
Keewatin = Lower Huronian = Crystalline schists of 
south shore invaded by granite-gneisses. 
Unconformity. 
Coutchiching. 
ARCH: AN + 
opel 
Van Hise in his latest publication uses the following classification 
of the formations *: 
CAMBRIAN, 
(Unconformity). 
KEWEENAWAN, 
(Unconformity). 
UPPER HURONIAN (= Penokee-Gogebic = Animikie), 
(Unconformity). 
LOWER HURONIAN (= Upper Huronian or Keewatin of Ontario), 
(Unconformity). 
ARCHZAN (Vermilion series, including Soudan iron formation, certain schists 
and intrusive granite and gneiss = Lower Huronian or Keewatin 
Ontario with Laurentian). 
In the arrangement given above three successions have been 
combined, omitting the local applications and adding the equivalent 
terms as recognized in Ontario. The unconformities are of very 
unequal importance, the one below the upper Huronian (—Animikie) 

2 Bur. Mines, 1902, p. 185. 
Wniv. Cally Violiis, Mons, p, 61. 
* U.S. Geol. Sur., 21st An. Rep., p. 338, p. 385 and p. 402. 
