632 REPORT— 1897. 



at that time, and may be accepted as Logan's last word on the subject. As thus 

 defined and established, he left the Laurentian and Huronian systems. 



In so far as the stratigraphical relations of the Laurentian, Huronian, and 

 'Upper Copper-bearing Series' are concerned (leaving out of consideration the 

 Labradorian), it is thus manifest that the conclusions originally formed from 

 actual study on the ground were those finally held by Logan. The reference for 

 a time of the Huronian proper and the ' Upper Copper-bearing Series ' together to 

 the Lower Cambrian, meant only that, as then understood, there was no other 

 systematic position recognised to which they could be assigned. That a great 

 unconformity existed between these two systems was never doubted, but for some 

 years Logan was not prepared to take the bold position of constituting a separate 

 Huronian system beneath the lowest Cambrian ; he was, on the contrary, anxious, 

 if possible, to bring the Canadian section within the lines established in the classic 

 region studied by Sedgwick and Murchison. The introduction of new systematic 

 terms was at that time considered somewhat seriously. When eventually com- 

 pelled to take this step (in 1857), he confined the name Huronian to rocks ante- 

 dating the great break at the base of the ' Upper Copper-bearing Series ' (Animikie), 

 embracing those first seen by him on the Upper Ottawa and on Lake Huron, with 

 their representatives elsewhere, under this new system. 



In so far as nomenclature goes, Logan thus certainly modified his original 

 application of the name Huronian ; it was not, however, as has been contended, to 

 create an ' extended Huronian,' but on the contrary to restrict the name to rocks 

 beneath the great unconformity at the base of the Animikie. The change was 

 necessitated by the progress of investigation and by the recognition of an upper 

 division of the ' Azoic,' beneath anything that could legitimately be classed as 

 Cambrian. It was made by the author himself, and involved no departure from 

 the law of priority or from any other acknowledged rule. In finally eliminating 

 these upper rocks from his Huronian system, he was no doubt influenced by 

 "Whitney's criticisms of 1857,* which were in part correct, although largely devoted 

 to the very conservative contention that all stratified rocks below the great break 

 were inseparable, and should be included in an ' Azoic System.' This influence 

 may be traced in an important paper, of but three pages, communicated to the 

 American Association for the Advancement of Science a few mouths later than the 

 date of that above referred to, in which, while the name Huronian is reaffirmed 

 for the rocks of Lake Huron and Lake Temiscaming, which are taken as typical of 

 the system, nothing further is said of those now known as Animikie and 

 Keweenawan. 



In the summary volume of 1863, to which allusion has already been made, the 

 existence of an Upper Laurentian, Labradorian or Norian Series was first tentatively 

 indicated in a supplementary chapter. It is unnecessary to follow here the history 

 of the rocks so classed, for the supposed series has not stood the test of later 

 discussion and re.search, due chiefly to Selwyn and Adams. The apparently 

 stratified rocks often included in it are now understood to be foliated eruptives. 

 The recognition achieved by this and by other more or less hypothetical series 

 about this time may be traced to the brilliant chemico-geological theories 

 advanced by Hunt, previous to the general acceptance of modern petrographical 

 methods. 



In a similar manner, and very justly so, Logan, as a field geologist, was in- 

 fluenced by the views held by Lyeil in the early editions of his ' Principles,' to 

 accept without reservation the foliation of crystalline rocks as indicative of original 

 bedding. This was, at the time of his early researches and thereafter for many years, 

 the accepted view, although Dana, in a paper read before the American Associa- 

 tion for the Advancement of Science in 1843, had already held that the schistose 

 structure of gneiss and mica-slate was insufficient evidence of sedimentary origin ; 

 and Darwin, a few years later, had published his ' Geological Observations,' includ- 

 ing a remarkable chapter on cleavage and foliation, in which he advocated a similar 

 view. No such doctrine, however, achieved general recognition until long after- 

 wards, while that class of facts remaining to be determined chiefly by the micro - 



' Am. Joiirn. Sci., vol. xxiii. May, 18.'i7 



