6 
MUSEUM BULLETIN NO. 22. 
dip more than 40 degrees, and dips of 15-30 degrees are com- 
monest. In fact, over a large area between Lake Tendinenda 
and Mississagi river the beds are nearly horizontal. Gentle 
folding is the characteristic structural feature of the region. 
But, as Lake Huron is approached the deformation becomes 
more and more pronounced. For example, the Huronian beds 
north of Mississagi river, near Dean Lake, dip about 15 degrees 
and in various directions. South of the river the dip increases 
rapidly to from 40 to 90 degrees and, finally, in the vicinity of the 
railway station, these beds are thrown against granite-gneiss 
by a great east-west fault. From Dean Lake eastward the 
Huronian strata are all steeply tilted, even overturned, and faults 
of various magnitudes are common. 
The extent of the intensely deformed Huronian formations 
is shown in Figure 1. The axis of folding crosses the district in 
a wide, southward-curved arc. About Echo lake and Bruce 
Mines, in the west, the strike averages south 30 degrees east, 
at Blind River it is due east, and, in the east, near Espanola 
and Lake Penage, it is north 75 degrees east. The southward 
extent of this area of disturbance is concealed by the over- 
lapping Palaeozoic formations. It probably continues eastward 
to near Lake Wanapitei, 
This area of deformation is an exceptional structural feature 
in northeastern Ontario and, naturally, one in which exceptional 
causative influences are to be expected. For this reason par- 
ticular attention was given to it, as shown below, between 
Algoma and Cutler, 
GEOLOGICAL RELATIONSHIPS NEAR CUTLER. 
Classification of the disturbed Huronian formations offers 
particular difficulty. The very fact that the rocks are so much 
more deformed than those in other parts of the district requires 
that the evidence for their comparison be unusually strong. 
At the same time it makes such evidence harder to obtain 
because the deformed rocks have been more metamorphosed 
than the less disturbed ones and their original lithological 
resemblances have been correspondingly obscured. It is necessary 
to depend more upon the actual tracing of formations from 
