28 c 



GEOLOGICAL SURVEY OF CANADA. 



Chain of 



straggling 



Jakes. 



Wintering 

 Lake. 



Wintering 

 Lake to 

 Sipi-wesk. 



Landing Lake. 



Cross Portage. 



Gneiss. 



Great dyke at 

 Standing-rock 

 Rapid. 



South-west- 

 ward strike. 



Character of 

 country along 

 Grass River. 



Nelson, for twenty miles, to the Standing-rock Eapid. A canoe-route, 

 seven or eight miles in length, leads from the head of this rapid across 

 to the Nelson. From this rapid the " river " is rather a chain of strag- 

 gling lakes connected by narrows, with more or less current, for thirty- 

 eight miles in a southwestward direction, to the head of Wintering 

 Lake, where the Pickerel Eiver flows in with the same upward course- 

 About half-way up this stretch, at Burnt Lake, the main branch of 

 the Grass Eiver joins the one we have been following. The short route 

 from Sipi-wesk Lake to Burnt-wood Eiver crosses Wintering Lake at 

 right angles. On the present occasion we followed the part of this 

 route lying between the latter and the outlet of Sipi-wesk Lake. The 

 distance is about fourteen miles in a general eastward direction. From 

 the eastern bay of Wintering Lake we made a portage of one mile and 

 ten chains to the western part of Landing Lake, which discharges into 

 the Nelson Eiver, seven or eight miles below Sipi-wesk Lake. A creek 

 only a few chains in length, entering the south side of Landing Lake, 

 conducted us to a small sheet of water, from which a trail, called Cross 

 Portage, one mile and a third long, brought us to the outlet of Sipi-wesk 

 Lake. 



I have already referred to the supposed Huronian rocks at the mouth 

 of the Grass Eiver. At about three miles from the Nelson, a rusty, 

 quartzose variety of gneiss dips S. 40° E. < 60°. For two miles 

 further up, hornblendic gneiss is seen in places, and at the end of this 

 distance it dips S. 10° E. < 80°. Here some large dioritic dykes run 

 across the river. At the first rapid, about seven miles from the mouth, 

 a ribboned felsitic red gneiss has also the same dip. 



At the Standing-rock Eapid, a great dioritic dyke crosses the river. 

 It is divided by vertical fissures, one of which has detached from the 

 main rock the mass (shown in the accompanying illustration) to which 

 the rapid owes its name. For about a mile above the rapid, the 

 gneiss, which dips N. 45° W. < 80°, is full of trap dykes. Thence all 

 the way along the route to the outlet of Sipi-wesk Lake, the rocks con- 

 sist of different varieties of gneiss, often cut by trap dykes. The general 

 strike in this interval is southwestward, the directions ranging from 

 about W. to S. 20° W. 



The country traversed by the Grass Eiver route between its mouth 

 and Sipi-wesk Lake presents generally an undulating appearance. 

 The land is usually of a clayey nature and the soil often good. There 

 seems to be very little swamp, as far as could be judged by following 

 the canoe-route. Along the river, and around the lakes on its course, 

 the rocks are seen beneath the clay on the islands and ends of points. 

 Half-way up the north-west side of Wintering Lake (which is fourteen 



