——— ee 
The Huronian Question.—Coleman. 331 
This argument applies only to the small area north of lake 
Huron described and mapped by Murray. It does not apply 
to the other localities described by Logan in his formal sum- 
ming up of the question in 1863, when his mature views were 
expressed; for the Huronian of lake Temiscaming and of 
Dore river consists of steeply dipping schists and slates. 
In reality the so-called typical Huronian is quite extep- 
tional in more ways than one, as may be seen by a comparison 
~with the other regions described. 
The dips of the strata mentioned by Logan and Murray 
are from 18 to 45° on a section near Echo lake, and more to 
the eastward they gradually diminish until just beyond Thes- 
salon they become nearly horizontal, with a slope seldom more 
than 6’; while in almost all other parts of the Huronian the 
dips are more nearly vertical than horizontal, and are often 
for long distances practically vertical. Even within a few 
miles on each side of the region studied by Murray we find 
the usual steep dips; e. g., at Garden river five miles west of 
Echo lake the dip of the Huronian limestone is 70’ to 80’; 
and a mile or two east of Blind river, just beyond the part 
mapped by Murray, the quartzytes and schist conglomerates 
have dips of from 75° to go’, more often the latter, and the 
same dips occur for fourteen miles to the east along the line 
of the “Soo” branch of the Canadian Pacific railway. 
One may safely say that dips less than 45° are everywhere 
rare except in the Thessalon region where Murray worked, 
and that in most parts the dips are not far from verticality. 
The cause of this is to be found in the fact that normally the 
Huronian of northern and western Ontario forms close folds, 
generally nipped in between Laurentian areas; while the area 
mapped by Murray has gentle open folds and has undergone 
less squeezing. 
One expects also to find the Huronian north of lake Hur- 
on less sheared and rearranged by the action of mountain 
building processes than elsewhere, and this is actually the 
case. The quartzytes, arkoses and “slate” conglomerates mak- 
ing up the bulk of the original Huronian are less schistose 
and less crystalline than the rocks of normal Huronian areas; 
but on the other hand they are more metamorphosed than any 
* Geol. Can., 1863, p, 62. 
