PRE-CAMBRIAN OF NORTHERN ONTARIO AND QUEBEC 313 



Both are deformed along east-west axes and the basal con- 

 glomerates of both are so similar that the writer has been unable 

 to distinguish them. In view of these facts there can be no reason- 

 able doubt as to the correlation of the two series. Since the 

 Pontiac series has already been correlated with other ancient 

 sediments of northern Quebec under the general name of Mat- 

 tagami series, a general correlation of northern Ontario and 



Fig. 3. — Sketch map showing the lineal distribution of the Timiskaming-Pontiac 

 series in Ontario and Quebec. 



Quebec is thus established. The name Timiskaming, which has 

 priority, will henceforth be used in this report in referring to these 

 sediments both in Ontario and Quebec, replacing the name Mat- 

 tagami series. 



ECONOMIC VALUE OF THE CORRELATION 



The correlation thus established possesses a certain economic 

 value which may now be briefly discussed. The writer has recently 

 shown^ that in the Matachewan district of northern Ontario valu- 

 able gold deposits have been formed through the action of juvenile 

 solutions originating from a body of cooling syenite porphyry. 

 Similar porphyries are found in many places through northern 

 Ontario, and very commonly in association with gold deposits. 

 While the genetic connection of the gold deposits with the por- 

 phyry has never been definitely proved, so far as the writer is aware, 

 in any district but that of Matachewan, still the frequency with 

 which the association occurs is extremely suggestive. The por- 

 phyries intrude the Keewatin volcanics in dikes, batholiths, and 

 rarely sills; when they intrude the Timiskaming series the bedded 



^Economic Geology, Vol. XIV (1919), pp. 281-301. 



