CHURCHILL AND NELSON RIVERS. lo C 



Lower Chain -of-Kocks (or Islands) Kapid, witli a descent of only about 

 two feet, occurs one mile further down. 



Between the (Jrand Ra]>id and the western part of Split Lake the <^nei8s. 

 ijneiss is partly reddish and parti}' ^voy and hornblendic. The strike 

 varies in ditlerent places from S. 60° to S. 80° W. It is cut by a num- 



. . . . Dykes. 



l»er of dykes of dark-coloured diorite, some of which, just below the 



junction of the (irass River, are very laru^e. Their run has a general 



north-and-south tendency. On the north side of Split Lake, opposite 



the two inlets of the Nelson, the gneiss is cut by numerous dykes of 



all sizes and running in many directions. Below Chain-of-Rocks 



Rapid, on the noi'th-west side of the river, dark gre}' quartzite and 



hornblendic schist occur, and also a dark green serpentinous-looking' ^ ^^^^' 



rock with a somewhat schistose structure. The Burntwood Rivor, a r"^^^''''** 



large stream, with turbid water like that of the Nelson, enters the 



western extremity of Split Jjake. On each side of the mouth of this 



river, the rocks consist of quartzose, felsitic and hornblendic slates, run- ^*'*^^***' 



iiing west-south-Avest, much cut up by trap dykes. At the Island of the 



Dead, in the entrance of the river, hornblendic schist is interstratified 



with ribbone<l quartzite, striking east and west. The rocks on some 



islands about a mile north-east of the western or principal inlet 



of the Nelson River, consist of dark bluish-green hornblende and mica 



schist, interstratified with ribboned gneissic bands and with irregular 



layers of softer, light green schist, all much contorted. The rocks of 



the point between the Nelson and Burntwood rivers, and the islands 



for two miles to the north-west of it, may be considered as Huronian, Huroniaii 



but beyon<l this, in the same direction, they pass into gneiss, consisting 



of thin hornblendic and micaceous layers, alteniating with others of 



quartz. 



Split Lake runs east-north-east, and is about twenty-tive miles long Split Lake, 

 by two or three wide. The rocks along its northern shore consist of 

 gneiss, which is generally of a hornblendic character, interstratified 

 with quartzose layers. Towards the west end the strike is about, east 

 and west, but elsewhere it is much disturbed. Besides the rocks of 

 Huronian character just described as occurring at this extremity of the 

 lake, a green hornblende rock, which was met with on an island near 

 the east end, may be of the same age. What appears to be another 

 limited area of Huronian rocks in this part of the country, is met with n'iiron'ian on 

 on the south side of the Grass River where it joins the Nelson. Here, ^'^^^ ^'^®''" 

 at about half a mile west of the Grand Rapid portage, there is a rib- 

 l)oned, slat}', hornblendic rock, together with a coarse variety, and a 

 dark gray quartzite, dipping S. 20° W. < 60°. These are cut by a 

 great dioritic <lyke, running about ixtHi and -^outh. SilioNnis and 



