
LAKE OF THE WOODS—JUNCTION HURONIAN AND LAURENTIAN. 45 
distance. The river and lake are only separated by a comparatively nar- 
’ row ridge of rock, through which there are three gaps. The furthest 
west, or Rat Portage proper, does not carry any water; the second or 
middle gap, is that of the Rat Portage Rapids; the third or east one, 
near the Hudson’s Bay Fort, that of the Rat Portage Fall. (Plate 2.) 
89. A band of slaty rocks, with an average width of about halfa mile, 
separates the greenstone-like series last described, from the Laurentian. 
Its lowest beds were seen just north of the greenstone, two and a quarter 
miles westward from the Hudson’s Bay Post, and at the entrance of the 
channel, which leads to Rat Portage proper. The rock is a very fine- 
grained micaceo-hornblendic schist of a dark colour, and quite hard; 
vertical, with a strike of N. 65° E. Entering the ‘viver-like inlet, which 
. leads northward and then westward to the Portage path, similar rocks 
are seen, but rather darker and more hornblendic. They appear to have ' 
a high northerly dip. The portage, from the waters of the lake to those 
of the river, at this place is not more than 150 yards long. The southern 
end of the path passes over Huronian rocks, which may be described as 
considerably altered slates, chiefily hornblendic, greenish-black in colour, 
crypto-crystalline, and silky in lustre. At the water’s edge,—where they 
are worn smooth by the feet of the voyageurs of old time,—they were 
found to be vertical, with a strike of N. 75° E. About half-way across 
the Portage, and at its highest part, the rocks dip N. 17° W. < 48°, and 
are then immediately succeeded by Laurentian gneiss, which is granitoid, 
and of a light pinkish-grey colour; dip N. 30° W. < 89°. The junction 
is so close that one may actually lay the hand upon it, and the separating 
line is remarkably straight and even. Followed about one hundred 
yards westward, it was found to preserve the course of S. 67° W., or 
nearly that of the strike of both series of rocks. The gneiss at this 
distance, has a strike of N. 72° E., and the green slate, just across the 
line of junction, and only a few yards removed, N. 73° E. 

90. About a mile eastward from the entrance to the portage, the lake 
finds one of its exits by a passage at right angles to its shore, down 
q which the water flows over a fine series of rapids. At an island opposite 
this opening, the same greenish hornblendic schist occurs, fine-grained, 
| and sometimes almost chloritic in aspect, as before. A long portage on 
- the eastern side of the rapids leads to the Winnipeg River, and a consid- 
erable breadth of very hard coarse-grained green diorite is exposed, 
which has not the aspect of any of the altered rocks seen in the vicinity 

of the lake. It has all the character of a mass intruded along the line of 
