low.] GEOLOGICAL OBSERVATIONS. 27 D 



Height of Land, and are described in the Reports of the Geological 

 Survey 1870-71 and 1871-72, by Messrs. Richardson and McOuat, 

 respectively. 



From these observations it may be concluded that, with the excep- f 



tion of the comparative y small areas of Cambro-Siluru 

 neighborhood of Lake St. John, and perhaps similar small areas at 

 other points not yet explored, all the rocks between, the Gulf of St. 

 Lawrence and the Height of Land are of Laurentian age. And these 

 rocks probably extend far beyond to the shores of Hudson Straits, 

 occupying the greater part of the Labrador peninsula, with but few 

 areas of newer rock overlying. On the west side of Lake Mistassini, 

 the coarse grained red gneiss, composed of quartz, orthoclase, mica 

 and hornblende, appear with a general strike of N. 30° E. The space 

 between Crooked Lake and this side being overlaid by the Cambrian 

 limestones which extend to the western shore of the lake. On the 

 Rupert River, the coarse-grained red gneiss predominates over the 

 finer-grained varieties. 



At the junction of the Marten and Rupert Rivers, and for some dis- 

 tance below, a darker gneiss, containing larger quantities of dark green 

 hornblende, appears. In the river, at the first portage of " The Fours," Trap dyke 

 a dyke of dark greyish-green dioritic trap, over twenty yards wide, 

 running S. 70° W., penetrates the red gneiss and holds gneissic frag- 

 ments near the plane of junction. 



Farther down the river, the exposures are fewer ; the last is at the 

 House Eapid, one mile above Rupert House and consists of the com- 

 mon red gneiss. Strike W. 10° S. 



HURONIAN. 



A series of rocks similar to the epidotic and chloritic slates of 

 the Shickshock Mountains and the Eastern Townships, is seen first 

 about forty miles south-west of the southern extremity of Lake Mis- 

 tassini. These rocks have been fully described by Mr. Richardson 

 in the Geological Survey Report for 1870-71, from which the following Richardson'; 

 is an extract : — 



"This series was first observed at the north end of Lake Abatago- 

 maw. Thence it occupies the country along the line examined, to and 

 along Lake Wakinitche, including Lake Chibogomou and the lakes and 

 portages between it and Abatagomaw [large lakes lying south-west of 

 Mistassini]. The last of it was seen at about two miles beyond the 

 outlet of Lake Wakinitche, nearly four miles in a straight line from 

 where it was first observed on Lake Abatagomaw. As already 

 stated, the rocks of this series are met with almost immediately- 



