Selwyn — Geological Age of the Saganaga Syenite. 321 



graphic generalization. Large areas that will eventually be 

 classed with the Huronian system have been colored on the 

 geological maps of Canada as Laurentian. These areas how- 

 ever had never been and even yet are not examined. A com- 

 parison of the map of Canada of 1866 with that of 1882 indi- 

 cates, though only partly, the extent of this error, and the 

 advance o£ our knowledge of the distribution of Huronian in 

 the interval. Thousands of square miles of territory in 

 Northern Canada remain to be explored before all the areas 

 occupied by the rocks of the Huronian system can be defined. 

 Unfortunately the literature of the system has gone very far 

 ahead of the knowledge of it derived from personal observa- 

 tion in the held. 1 have probably examined these rocks in the 

 field over a wider geographical extent than any other geologist 

 but have taken little part in the literature respecting them. 

 I have however strongly deprecated the term "typical Hu- 

 ronian," and then using the very imperfect descriptions given 

 in the early reports of the Canadian Survey of one small par- 

 tially mapped area, viz : that on the shore of the north chan- 

 nel of Lake Huron, in arguments against the subsequent 

 correlation with it of other areas. The chief arguments being 

 based on the local greater development of some particular kind 

 of rock as quartzite, etc., and low angles of dip — the latter 

 being, however, if not indeed both, a wholly incorrect assump- 

 tion. That it is so as regards the latter can be proved by the 

 maps of the so-called " typical " area made by Mr. Murray and 

 published in 1857 in atlas form. 



Local development of any particular kind of rock is of no 

 import in the correlation of systems, neither are high or low 

 dips. The Archsean rocks in Canada, Laurentian and Huronian, 

 are sometimes flat and locally dip at all angles, from that to 

 vertical and yet low dips and local lithological characters have 

 been the main reasons adduced by some of the writers on 

 Huronian against the correlations made by the Canadian Sur- 

 vey, all of which are, however., based on careful observation in 

 the field, and are as well founded as, in the absence of paleon- 

 tological evidence, is possible. Every other kind of strati- 

 graphic evidence is present and I hold it amply sufficient for 

 the purpose of stratigraphic correlation. 



In the present state of our knowledge of Archgean forma- 

 tions no new name is required in Canada, for this great sys- 

 tem. As its subdivisions become worked out, local names, as 

 Coutchiching and Keewatin, can be used to designate them, 

 and if, as is possible, though I think not probable, some part of 

 it should eventually be proved, by the discovery of fossils, to 

 belong to the Paleozoic era, it can be separated under some 

 appropriate designation. 



