1907-8.] THE GEOLOGY OF THE LAKE WENDIGOKAN REGION. 353 
region might, under certain conditions, reduce the hematite to magnetite. 
In an analysis of a piece of the slate from the iron range on Whitefish 
Lake there was found a loss of 6.02 per cent. on ignition, and this loss can 
be mostly attributed to the presence of carbon. In some places these 
slates are quite abundant in the iron formation, but in others there are 
large masses of banded silica and jasper without any mechanical deposits 
and these conditions must be accounted for in much the same way as the 
interbedding of limestone and shale. The chemical precipitates of white 
silica and jasper must have been deposited, like limestone in comparatively 
clear water, and the slate, like shale, in water carrying much mechanical 
sediment. 
' "Some writers have suggested that the chemical sediments of the 
iron formations were deposited from superheated sea water. It is im- 
probable that the sea over any great area was at a high temperature 
during this time, nor is this conditions necessary, because silica can be 
deposited in the amorphous condition from water which is not at a very 
high temperature, and if deposited in the amorphous condition it would 
no doubt undergo a re-arrangement of its molecules and take on a crystal- 
line condition under the action of metamorphic agents, just as the amor- 
phous silica of the skeletons of some animals becomes crystalline. Or 
on account of the presence of alkalies in the sea water the silica might be 
deposited from solution of the alkali silicates at ordinary temperatures, 
A boulder containing specular hematite and quartz crystallized together 
was found in the region, and it is interesting in showing how these sub- 
stances crystallize from water at a high temperature. I think it quite 
correct to assume that the water was hot in this case, because the silica 
is in the form of perfect quartz crystals and the fine crystals were formed 
in a cavity so that they have not been subject to metamorphic influences 
since their formation. 
The strike of the iron formation in the northern part of the region 
is nearly east and west, and in the southern part about 70 degrees. ‘This 
difference in strike brings the eastern ends of the bands rather close to- 
gether, while they are some distance apart at the western end. The dip 
of most of the bands is nearly 90 degrees, though in location BTor, the dip 
is about 75 degrees north, and in HF 35 70 degrees southward, while be- 
tween the two outcrops a narrow band dips at about 90 degrees. ‘This 
condition suggests a closed fold having the anticlines removed by erosion, 
and the outer limbs of the anticlines dipping north and south and the 
inner ones standing vertically, but in the other bands of the formation 
the dip is almost always about 90 degrees or indefinite, and I concluded 
that the folding was on a smaller scale and more complicated. The rocks 
