﻿428 Canadian Record of Science. 



appear to be valleys of denudation and are of very ancient 

 origin, antedating the Cambrian ; undisturbed, horizontal 

 beds of Cambrian age being found deposited upon their 

 lower levels. The gorges of the Hamilton, Sandwich and 

 Kaipokok might be cited as examples as well as those of 

 the Moisie and Saguenay discharging into the Gulf of St. 

 Lawrence. 



About nine-tenths of Labrador is underlain by rocks of 

 Laurentian age, and like all the rest of the glaciated 

 Laurentian country, the plateau is studded with myriads 

 of lakes great and small, which are estimated to occupy at 

 least one-fourth of the total surface, and which are. 

 drained by a network of streams discharging into the 

 deep fjords above referred to. The Peninsula is underlain 

 exclusively by the oldest rock systems of the earth's crust, 

 the Laurentian, Huronian and Cambrian, together with 

 certain rocks of intrusive origin. The Laurentian rocks 

 differ in no essential particular from those found elsewhere 

 in Canada. Both the Fundamental Gneiss and the 

 Grenville Series are largely represented, the latter running 

 in wide and persistent bands across the country and 

 consisting of micaceous gneisses and schists, quartzites, 

 crystalline limestones, etc., often holding graphite. Great 

 anorthosite intrusions cut these rocks, from certain of 

 which is derived the precious labradorite. 



The Huronian is represented by several widely separated 

 areas of clastic and volcanic rocks, together w^ith many 

 basic eruptives. They consist of schists of various kinds, 

 with conglomerates, breccias, diorites and other rocks. 

 The Laurentian and Huronian are intensely folded, the 

 folding having taken place at a time long prior to the 

 deposition of the sedimentary beds of Cambrian age, and a 

 sufticiently long time had elapsed, as has been mentioned, 

 between this period of folding and tlie Cambrian submer- 

 gence to permit of enormous denudation and erosion. 



The Cambrian strata, wliicli rest unconformably upon 

 •the Laurentian and Huronian, consist of bedded sand- 



