<9 
THE BOHEMIAN RANGE. 185 
belongs plainly enough to a class of rocks which has been recognized at a 
number of other points in the extent of the formation, and which includes 
also some of the beds immediately over the Greenstone. 
Externally this rock appears to be a mixture of a greenish mineral, 
with red feldspar and rare magnetite. The thin section shows the principal 
ingredients to be orthoclase, oligoclase, augite, diallage and titanic iron, 
the augitic mineral being largely altered to a green uralite, and this still 
further to a chloritic substance; while very abundant apatite, a gray sub- 
stance secondary to titanic iron, a little secondary quartz and secondary 
magnetite, are all to be seen. The thin section of this rock is pictured in 
Fig. 3, Plate V. 
All of the exposures on the bluffs immediately north of Lac La Belle, 
and of the shore cliffs at the head of Béte Grise Bay, seem to point to a 
very high northern dip, the strike in this distance varying between north of 
east and north of west. 
Foster and Whitney speak of a belt of “chlorite” as always occurring 
on the south flank of the Bohemian Range, at the contact with the Eastern 
Sandstone. They also map it as extending all the way from Béte Grise 
Bay to Portage Lake.’ It does not appear to me, after seeing this contact 
at Béte Grise Bay, at Lac La Belle and on the Douglas Houghton River 
near Torch Lake, that the supposed chlorite belt is anything more than the 
usual diabase or amygdaloid greatly decomposed, as it naturally would be 
along such a contact, and probably also much broken up, as would be the 
case along such a fault as must have taken place at this contact.” Even at 
these places the decomposition varied greatly in extent, and there was no 
evidence of any continuous belt, the sandstone being seen at times exactly 
in contact with a not unusually altered diabase. The contact line between 
the sandstone and north-dipping traps does not follow exactly any one 
horizon, but crosses the trend of the trappean belts back and forth in the 
more easterly part of the point, and farther west rises quite rapidly in the 
series. 
It is worthy of note in this place that the account of the Bohemian 
1 Foster and Whitney, op. cit., pp. 65-67. 
2 The original faulting is believed to have antedated the sandstone, but faulting has taken place 
here since this sandstone was formed. 
