124 ROYAL SOCIETY OF CANADA 



gneisses and limestones, which, when present, apparently constitute the 

 lowest member ; while their resemblance to the rocks of the upper divi- 

 sion in Canada is also well seen. 



The question has lately arisen as to the most siiitable line of division 

 between the Laurentian and Huronian systems. Under the new deter- 

 minations as to the origin of the Laurentian gneisses, it is now generally 

 admitted that the greater part of these is of igneous instead of sedi- 

 mentaiy origin ; while portions of the Grenville series, usually regarded 

 hitherto as an integral portion of the Laurentian, are as clearly sediment- 

 ary in character. The original view as to the position of the Hastings 

 series, according to Vennor, who first made a careful study of the rocks 

 of this division, placed these above the gneiss and limestone of the Gren- 

 ville series, and regarded them as probably Hui'onian. The recent studies 

 of the whole series over a very large area, both in Ontario and Quebec, 

 tend to show that the rocks of the Grenville and Hastings series may be 

 classed together, and that, while containing large areas of clearly igneous 

 material, they both contain a large development of altered sediments. If, 

 then, the Hastings may be regarded as Huronian, as from their litho- 

 logical character and position they were originally considered, the sedi- 

 mentary portion of the Grenville may, with equal reason, be assigned to 

 the same place in the geological scale. This scheme would then give a 

 convenient basis of classification for the entire sedimentary series, and 

 the arrangement of the systems for eastern Canada would thus fall under 

 the following order : 



Laurentian, Non-Sedimentary. 

 Eau» or Fundamental Gneiss (Ottawa gneiss), representing in altered 

 form the original crust of the earth, and the lowest known series of rocks ; 

 without evidence of sedimentary origin. 



Huronian, Partly Sedimentary and Partly Igneous. 



Grenville and Hastings series, comprising limestones, quai'tzites, 

 gneisses, etc., of Ontario and Quebec, in the Ottawa district. 



Schists and altered slates, chloritic and other crystalline rocks of the 

 Eastern Townships of Quebec, and the Gaspé peninsula. 



Felsitic and gueissic rocks of northern New Brunswick. 



Gneiss, quai'tzite and limestone, of the so-called Laurentian of 

 southern New Brunswick, regarded as the equivalents of the Grenville 

 and Hastings series, felsites and schistose rocks of the Cold brook, King- 

 ston and Coastal divisions, the apparent equivalents of the rocks of the 

 Sutton mountain anticlinal. 



Felsitic and syenitic rocks of eastern Nova Scotia and northern Cape 

 Breton, with their associated crystalline limestones and serpentines. 



Cambrian. 

 Cambrian slates, sandstones and conglomerates. 



