4M C. K. LEITH 



series in a less altered form. That is, the Fundamental Gneiss, upon 

 which the Hastings series was originally laid down, having at a sub- 

 sequent time been softened by the influence of heat, and having under 

 the influence of dynamic action eaten into and fretted away the over- 

 lying Hastings series, gave rise to an intermediate zone of mixed 

 rocks which constitutes the Grenville series. The Grenville series 

 may, however, represent only a portion of the Hastings series, and the 

 work so far done has been insufficient to determine the stratigraphical 

 position of this portion. It seems probable that the age of the 

 Hastings series will be shown to be Huronian. 



The Grenville and Hastings series are unconformably overlain by, 

 and disappear to the south beneath, flat-lying Cambro-Silurian rocks. 



Ells 1 gives a general account of the Archean of eastern Canada, 

 including a review of the various classifications made by the earlier 

 geologists, and their recent modifications. It is concluded that it is 

 possible to reduce the great series of the so-called Laurentian rocks to 

 two principal divisions, viz., a lower Basal or Fundamental Gneiss, in 

 which all traces of sedimentation are wanting, and which may be 

 regarded as representing in altered form some portion of the original 

 crust of the earth; and a newer, secondary series, derived doubtless 

 from the decay of the former, in which the evidences of clastic origin 

 are manifest. On this basis the arrangement of the systems for 

 eastern Canada would be as follows : 



LAURENTIAN, NON-SEDIMENTARY 



Basal 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, quartzites, 

 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 Gaspe peninsula. 



Felsitic and gneissic rocks of northern NeV Brunswick. 



Gneiss, quartzite, and limestone, of the so-called Laurentian of 

 southern New Brunswick, regarded as the equivalents of the Grenville 



1 Notes on the Archean of eastern Canada, by R. W. Ells: Proc. and Trans. 

 Royal Society of Canada, 2d series, Vol. Ill, 1897, Sec. 4, pp. 1 17-124. 



