30 KOYAL SOCIETY OF CANADA 



field, which 1ms extended over a very large area, and by a comparison of 

 points of structure at widely separated places. As a consequence, the 

 many widely differing conclusions which have been put forward for near- 

 ly half a century, have, in many cases, been reconciled, or have given 

 place to others, based on the more modern methods of investigation. 

 Thus instead of the somewhat broad generalizations, which were, to a 

 large extent, founded on scattered and often insufficient data, in the 

 earlier work of the staff of the Geological Survey, it has been found 

 ])0ssible, by combining the information already thus obtained, with a 

 more careful attention to details of structure, to arrive at conclusions 

 which appear to be much more reasonable and satisfactory to the worker? 

 iu this field than could possibly be reached, not many years ago. 



The old view which Held that the lowest gneiss and granites were 

 Primitive or Primary, considering these as the first rocks which appeared 

 after the consolidation of the earth's crust, was doubtless correct in so far 

 as it went, and sufficed for the time being, while other great questions of 

 structure were under consideration. Subsequently as the study of these 

 rocks progressed, new aspects of the question were presented, and 

 modifications of the original theory became necessary. While therefore 

 tlie old name Laurentian and Huronian will probably always be con- 

 tinued in the nomenclature of our oldest known rocks, the areas assign- 

 able to each of these will doubtless undergo considerable modification 

 as our investigations in this direction continue. As, moreover, the de- 

 termination of these points of structure are in many cases intimately 

 connected with great questions of economic importance, the acquisition 

 of knowledge as regards the true relations of the several members of the 

 series is greatly to be desired. 



In this connection, among the most important questions which no^\■ 

 present themselves, is the determination of the portion which may be 

 strictly regarded as representing the Fundamental rocks of the whole 

 series. In this category has been placed for many years a great as- 

 semblage of strata, some of which without doubt are referable to the 

 oldest formed granite-gneiss formation, while other portions of these 

 should undoubtedly have been assigned to a higher position in the geo- 

 logical scale. To some extent this was done long since, by the use of the 

 term Huronian, and by the transference thereto of certain portions which 

 presented features indicating that they were of a different origin from 

 the basal gneis?; but there still remain other large areas, whose exact 

 horizons must still to some extent be regarded as not yet quite definitely 

 fixed, nnd these will doubtless, for some time, continue to afford ma- 

 terial for discussion. 



The multiplication of names for rock groups, where the horizons 

 arc not determined, and where, as in certain districts, their relations are 



