^LL.] LAURBNTIAN SYSTEM. 17 I> I» 



" Tho Sihii'ian limestones, overlying the oKl crystalline rocks, have 

 been already mentioned. The same are found Wosidos in Field Bay, 

 and they compose nearly the whole northern coast of Maffln Lund. 

 Hall found sandstone at Lock's liand, which iterhaps beloni's to theR««!l«»or(»ih«r 

 vftrboniterous formation. It is said to resemble that found by Parry locsiiiiet. 

 at Antrid^o Bay ( Fur}' and Hecia Strait). Hero may also \to men- 

 tioned tho samples of sandstone found by Bessils at Point Garry. 

 From accounts by Captain Walker of the ship " Krik." coal is found in 

 loose boulders in a stream at Kclipse Sound and on Aggidjeu (Durban 

 Island)." 



The gneissic rocks within the immense area which has been de- 

 scribed, no doubt i-epreseat a great period of geological time, and com- 

 prise a vast thickness of strata, tho amount of which it would bo 

 impossible to determine with any degree of accuracy. Certain are is 

 of a masbive granitoid character, are regarded as " primitive" gneiss, 

 and there is little doubt they are more ancient than those Laurentian 

 i-ocks which are regularly and distinctly stratified, and consist of bands 

 of different lithological characters, such as prevail in the Ottawa valley. 

 As a general rule, in the great region around Hudson's Bay, tho K"^''*'* <'haracte of 

 is of a very monotimous character, consisting of the commoner reddish Kne'*='e'»- 

 and greyish varieties. It is mostly massive, highly crystalline and ^ 



hard, except where it has been exposed for ages to atmospheric intlu- 

 ences, as in the non-glaciated districts. The fresh rock will break 

 almost as e."sil\- across the lines of stratitication as parallel with them. 

 The average direction of the lamination is sometimes pretty constant 

 over a considerable extent of country, but it is as frequently, greatly- 

 contorted on tho small scale, and so much disturbed on the large scale 

 as to render it almos. impossible to trace out and map its structure. 

 The gneisses of thi« icind are not known to caiTy any useful minerals, useful 

 except such as mica and felspar in coarse granite veins. On tho other ™'°®'**" 

 hand, in the more southern districts, where tho gneisses are somewhat 

 regular, and where their different divisions are capable of being mapped, 

 we find phosphate of lime, graphite, limestone, barytes, serpentine; 

 magnetite and hematite, pyrites, gelena, copper ores, &c. These rocks 

 appear to be newer than the massive gneisses which prevail in the 

 north. 



The continuity and the geographical compactness of the great i^^ta- g^jj^^^^^ ^^ 

 niorphic or Laurentian area of the north-eastern part of the continent relationship 



' ^ in age. 



are themselves evidences of the close relationship in age of the rocks 

 comprised within it, whereas there is more room for uncertainty on 

 this point in reference to widely separated areas of metamorphic rocks 

 more or loss surrounded by newer formations. The various bands of 

 rock which in Canada have been recognized under the name Huroniau 



