142 ROYAL SOCIETY OF CANADA 
Unfortunately, the two clues which solved the relationships of 
the Huronian areas, the banded silica of the iron range in the lower 
Huronian or Keewatin, and the basal conglomerates containing 
iron range pebbles in the upper Huronian, cannot be applied to the 
southeastern Archæan, since nothing corresponding to the banded 
iron range jaspers has been found in them. Iron ores are common 
among them, but never interleaved with silica. 
The Grenville must be earlier than the Laurentian, since the 
latter has been plastic enough to nip in bands of Grenville limestone 
before it solidified; but I have seen no conclusive evidence as to the 
relationship of the Hastings series to the Laurentian. 
The age relationship of the Grenville rocks and the Laurentian 
gneiss is not always stated as given above. Drs. Adams and Barlow, 
for instance, say “ the relations of the Grenville series to the Funda- 
mental Gneiss are such as to suggest that in the former we have a 
sedimentary series later in date than the Fundamental Gneiss, which 
has sunk down into and been invaded by intrusions of the latter series 
when this was in a semi-molten or plastic condition.” However, 
a little later they say that “ masses of the highly crystalline lime- 
stone or marble in some cases lie quite isolated in what are, to all 
appearances, the lower gneisses, as if they had been separated from 
the parent mass, and had passed outward or downward into the 
gneissic magma.” “The contact of the Fundamental Gneiss and the 
Grenville series would appear, therefore, to be a contact of intrusion, 
in very many cases at least.” * 
Still later they suggest that the Grenville series bears the same 
relation to the Fundamental Gneiss as the Huronian does further 
west, the similarity, however, not implying identity in age. From 
the quotations given it will be seen that their view is not really differ- 
ent from that advocated by Lawson and in this paper for the lower 
Huronian or Keewatin. In my opinion, however, the date of an 
eruptive rock should be determined by the time of its final consolida- 
tion, which would, of course, place the Laurentian gneiss as described 
by Adams and Barlow later than the Grenville limestone which it 
has invaded. This does not imply that the Grenville series, or the 
Coutchiching and Keewatin of the west, the oldest known rocks, were 
founded on nothing; but that their foundations have since been 
become semi-molten, or at least plastic, and have then cooled and 
crystallized as our present gneiss. The materials are Pre-Grenville, 
but the gneiss is later in age. 
That the Hastings and Grenville series occupy the same position 
between the Laurentian and the Paleozoic sediments as the Keewatin 


1 Am. Jour. Se., Vol. III., Mar., 1897, p. 176. 
