August 26, 1897] 



NATURE 



401 



arbitrary line certainly, for the time, must be considered as 

 placing the Cambrian reference of the l>eds in question in 

 doubt ; but it does not interfere with a belief that if they should 

 be found to be lower than Cambrian as thus defined, they may 

 at least be considered as still in all probability Palneozoic. 



The definition of the horizon of Qleiielhis as that of the base 

 of the Cambrian is a question almost entirely palieontological, 

 into which it is not proposed here to enter, further than to point 

 out that it is only partially justified by what is known of North 

 American geology. In the Atlantic province, and in the 

 Appalachian region, there appears to be a very general physical 

 break at about this stage, which it seems likely may correspond 

 with the great unconformity at the base of the Animikie ; but in 

 the Rocky Mountain or Cordilleran region the Olenellus zone 

 has been found high up in a series of conformable and similar 

 sediments, coinciding with no break, and from these lower 

 sediments some organic forms have been already recovered, but 

 not such as to indicate any great diversity in fauna from that of 

 the recognised Cambrian. Similarly, in one part of eastern 

 Canada, Matthew has lately described a fauna contained in 

 what he names the Etcheminian group, regarded by him as 

 earlier than the Olenellus zone, but still Palaeozoic. Recent 

 discoveries of a like kind have been made in other parts of the 

 world, as in the Salt Range of India. These facts have only 

 last year been particularly referred to by Mr. Marr in his 

 address to the Section. 



The general tendency of our advance in knowledge appears, 

 in fact, to be in the direction of extending the range of the 

 Palaeozoic downward, whether under the old name Cambrian, 

 or under some other name applied to a new system defined, or 

 likely to be defined, by a characteristic fauna ; and under 

 Cambrian or such new system, if it be admitted, it is altogether 

 probable that the Animikie and Keweenawan rocks must 

 eventually be included. 



In other words,the somewhat arbitrary and artificial definition 

 of the Olenellus zone as the base of the Cambrian, seems to be 

 not only not of world-wide application, but not even of general 

 applicability to North America ; while, as a base for the Palaeozoic 

 ^on, it is of still more doubtful value. In the Cambrian period, 

 as well as in much later geological times, the American continent 

 does not admit of treatment as a single province, but is to be 

 regarded rather as a continental barrier between two great 

 oceanic depressions, each more or less completely different and 

 self-contained in conditions and history — that of the Atlantic 

 and that of the Pacific. On the Atlantic side the Olenellus zone 

 is a fairly well-marked base for the Cambrian ; on that of the 

 Pacific it is found naturally to succeed a great consecutive and 

 conformable series of sediments, of which the more ancient fauna 

 is now only beginning to be known. 



In thus rapidly tracing out what appears to me to be the lead- 

 ing thread of the history of the pre-Cambrian rocks of Canada, 

 and in endeavouring to indicate the present condition of their 

 classification, and to vindicate the substantial accuracy of the 

 successive steps taken in its elaboration, many names and 

 alternative systems of arrangement proposed at diff'erent times, 

 by more or less competent authorities, have been passed without 

 mention. This has been done either because such names and 

 classifications appear now to be unnecessary or unfounded, or 

 because they relate to more or less local subdivisions of the 

 ruling systems which it is not possible to consider in so brief a 

 review. This has been particularly the case in regard to the 

 much-disputed region to the south of Lake Superior, out of 

 which, however, after some decades of complicated and warring 

 nomenclature, a classification, trending back substantially to 

 that originally established and here advocated, is being evolved 

 (albeit under strange names) by the close and skilful strati- 

 graphical work in progress there. 



It has also been my object, in so far as possible, by omitting 

 special reference to divergent views, to avoid a controversial 

 attitude, particularly in respect to matters which are still in the 

 arena of active discussion, and in regard to which many points 

 remain admittedly subject to modification or change of state- 

 ment. But in conclusion, and from the point of view of 

 Canadian geology, it is necessary to refer — even at the risk of 

 appearing controversial— to the comparatively recent attempt to 

 introduce an " Algonkian System," under which it is proposed 

 to include all recognisable sedimentary formations below the 

 Olenellus zone, assumed for this purpose to be the base of the 

 Cambrian. If in what has already been said I have been able 



NO. 1452. VOL. 56] 



correctly to represent the main facts of the case — and it has- 

 been my endeavour to do so — it must be obvious that the 

 adoption of such a "system" is a retrograde step, wholly 

 opposed, not only to the historical basis of progress in classi- 

 fication, but also to the natural conditions upon which any 

 taxonomic scheme should be based. It not only detaches from, 

 the Palaeozoic great masses of conformable and fossiliferous 

 strata beneath an arbitrary plane, but it unites these, under a 

 common systematic name, with other vast series of rocks, now 

 generally in a crystalline condition, and includes, as a mere 

 interlude, what, in the region of the Protaxis at least, is one of 

 the greatest gaps known to geological history. In this region 

 it is made to contain the Keweenawan, the Animikie, the 

 Iluronian, and the Grenville Series, and that without in the 

 least degree removing the difficulty found in defining the base 

 of the last-mentioned series. It thus practically expunges the 

 result of much good work, conducted along legitimate lines of 

 advance during many previous years, with only the more thai> 

 doubtful advantage of enabling the grouping together of many 

 widely separated terranes in other districts where the relations 

 have not been even proximately ascertained. It is in effect, to 

 my mind, to constitute for geology what was known to the 

 scholastic theologians of a former age as a limbo, appropriate as 

 the abode of unjudged souls and unbaptised infants, that might 

 well in this case be characterised as " a limbo large and broad."" 



It is not intended to deny that there may be ample room for 

 the introduction of a new system, or perhaps, indeed, of an 

 entire Geological .-Eon, between the Huronian, as we know it 

 in Canada, and the lowest beds which may reasonably be con~ 

 sidered as attaching to the Cambrian, or even to the Palaeozoic 

 as a whole. On the contrary, what has already been said will, 

 I think, show that in the re;;ion of the Protaxis we might very 

 reasonably speak of an " Algonkian hiatus," if we elect so to call 

 it. Elsewhere it will undoubtedly be possible, sooner or later, 

 to designate series of rocks laid down during the time repre- 

 sented only by orogenic movements and vast denudation in the- 

 province here more particularly referred to ; but before any 

 general systematic name is applied to such terranes they should 

 be defined, and that in such a way as to exclude systems already 

 established as the result of honest work. 



It seems very likely, for instance, that the Grand Caiioi> 

 Series, as last delimited by Walcott, separated by unconformities 

 from the Tonto Cambrian above and the probably Archtean 

 rocks below, may be referable to such an intermediate system ; 

 but here it may be noted, in passing, that the attempt to apply 

 the new term "Algonkian " in this particular Western region, ha.s- 

 led to the inclusion under that name of a great unconformity 

 below the Grand Canon Series, much resembling the post- 

 Huronian break in the Lake Superior district. 



For such unclassed rocks, wholly or in large part of sediment- 

 ary origin, the Canadian Survey has simply employed the term 

 pre-Cambrian, involving for certain regions a frank confession of 

 ignorance beyond a certain point. Indefinite as such a term is^ 

 it is believed to be more philosophical than to make an ap- 

 pearance of knowledge not borne out in fact, by the application 

 of any systematic name not properly defined. 



Although it would be unsuitable, at the close of this address, 

 to introduce the old controversy respecting the Cambrian and 

 Silurian, it may be noted that the ethical conceptions and many 

 of the principles involved in that discussion still apply with un- 

 diminished value, and much of its literature may be re-read to- 

 day with advantage. More particularly I would allude to 

 Sedgwick's inimitable and now classic introduction to McCoy's 

 " Palaeozoic Fossils," one passage in which, paraphrased only by 

 the change of names involved in that and in the present dis- 

 cussion, may be read as follows : — " ' Est Jupiter quodcunqtie 

 vides ' was once said by Dean Conybeare in mockery of the old 

 despotic rule of the name Greywacke. A golden age of truth 

 and reason, and slow but secure inductive logic, seemed to- 

 follow, but the jovial days of a new dynasty are to spring up, it 

 seems, under a new name not less despotic than the one which 

 had ruled before it. If all the [sedimentary] rocks below the 

 [Olenellus zone] are to pass under one name, let us cling to the 

 venerable name Greywacke. It can do no mischief while it 

 describes things indefinite, simply because it is without meaning. 

 But the name [Algonkian], if used in the same extended sense^ 

 is pregnant with mischief. It savours of a history that is 

 fabulous ; it leads us back to a false type ; it unites together as- 

 one systems that nature has put asunder." 



