| COLEMAN] CLASSIFICATION OF THE ARCHÆAN 139 
miles east and west to localities when they have been nipped in as 
close folds and stand nearly vertical. 
The American geologists who have attempted to correlate the 
Pre-Cambrian west and south of the Great Lakes with the Huronian 
to the north have usually contented themselves with a visit to the 
easily-reached shore between Thessalon and the Sault, and have 
carried away a quite false impression of the typical Huronian. In 
reality, the other sections described by Logan are far more typical 
than the one mapped, when compared with the great areas of Pre- 
Cambrian worked out since his time. 
It is probable that the fundamental error of Irving in confound- 
ing the Animikie with the Huronian was due to his belief that the 
characteristic rocks of the latter lay nearly flat and were comparatively 
little changed sediments. If he had gone to Blind river, ten miles 
east of the region he visited, he would have found the same rocks much 
more metamorphosed and in a vertical attitude. 
To some extent Lawson, who had not visited the region, however, 
was misled also in his questionings as to the relative position of his 
Keewatin and the Huronian. His schist conglomerates with their 
iron range pebbles, as on Shoal lake, are undoubtedly the equivalents 
of the slate conglomerates of the Huronian, the basal member of the 
upper division, and there are examples of banded silica and iron ore 
associated with his Coutchiching which, no doubt, represent the iron 
range rocks forming the upper part of the lower division at Michi- 
picoton, one of the regions which Logan put in the Huronian. How- 
ever, the vast series of ash rocks, agglomerates and sheared eruptives 
of the Rainy lake and Lake of the Woods regions have few parallels 
in other Pre-Cambrian regions of Ontario, and the gray fine-grained 
mica schists and gneisses of the Coutchiching scarcely occur east of 
Lake Superior in regions mapped as Huronian; so that the introduc- 
tion of new names was thoroughly justifiable. 
RELATION OF THE LAURENTIAN TO THE HURONIAN. 
There remains one more subject to discuss before a classification 
of the Pre-Cambrian of northern and western Ontario can be taken up, 
the relationship of the Laurentian to the Upper Huronian or Huron- 
ian proper. It has been proved by Lawson that the Ontarian, as he 
names the Coutchiching and lower Keewatin, has been penetrated 
eruptively by the gneisses of the Laurentian which rose dome-like 
beneath them, nipping them into synclines, carrying off fragments of 
them and sending dikes into the steeply tilted schists. The eruptive 
character of the contact has been accepted by almost all geologists 
