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iiY oi' tiik (^ikuki^ (iiioip AM) riii: ()l\)Va\ rijvsTALiJXK Rocks of Canada. I)n\cti>r of i/ir Dominion {;,nlooical and Xt/n/a/ History Snrrrx. ,1 ■■:■' -.'('■^ ^■:My'^ M v^v \ :^}t$}:'0^,'y^o^^^^^^^ TSX^ ■ , v> ■■/■■ 4 ' '''^\ ' ^r)Mu. f-X>f.i J '^ .'^ .->'j,^' , '■■"■■ 'fej^V- I .V ' ('\' ■>;v^.;;-: '^"■''^^iN^'/r-'V: ^ ; /T: /:<-^cc. THE STRATIGRAPHY OF THE QUEBEC GROUP AND THE OLDER CRYSTALLINE ROCKS OF CANADA. By Alfred R, C. Selwyn, F.K.H., F.G.S., Director of the Dominion Geologrical and Natural History Survey. T propose in this paper to state as briefly as possible the con- clusions I have arrived at from examinations made in the field during the seasons of 1876 and 1877 with the object of satisfyin in rear of the Qurbec citadel. Tills I hold to be a mistake, and I think it can be distinctly shewn that it passes from th«.- south-west end of the Island of Orleans under the river and between Point Levis and Quebec ; it appears again on the north shore about one mile north of Point Pizeau, passes north of St. Foy, and thence in a direct course to where it again cros.ses the river south-west of Cap Rouge. Tiie entire absence of Levi.'* fossils in the Citadel rocks is thus easily explained. I have traced this break carefully from the last-named point on the north shore of the St. Lawrence to the north-east end of the Island of Orleans, where on the beach the actual contact of the two formations is well seen, and a short distance inland we find the characteristic Levis limestone conglomerate. Sidterella and Archixocyathas occur both at Point Levis and on the Island of Orleans, and the graptolite (^Phylogruptus) shales are interstrati- fied both above and below the limestone conglomerates. Oholella occurs also in shales clearly above the conglomerates and below other shales holding graptolitcs, and in some beds both occur together. ^ ■^ As rc<;ards the belt of Potsdam rocks — upper, middle and lower — which have been described in the Geological Survey Re- port tor IHOO-dO. pp. 119-141, T must state, that after having carefully examined some portions of these supposed Potsdam rocks, I hold that there are no reasons whatever for separating them from the Ldvis formation, either stratigraphical or palgeon- tological. Obolella, grapt.olites, and fragments of other fossils, too indistinct to be determined, have been found in them. On the south-eastern side, the fossiliferous belt is bounded by a line which, commencing on the United States boundary near St. Armand, runs on a course nearly parallel with the St, Law- rence, passing through the townships of Dunham. Brome, Shefford, Stukeley, Melbourne, Cleveland, Tingwick, Chester, Halifax and Leeds, to the vicinity of St. Marie on the Chaudiere. Be- tween St. Marie and St. Claire on the Etchemin River, the strata which I Jiave referred to division 2 increase greatly in width, cropping out. apparently unconformably, from beneath the fossiliferous belt and separating it from division 3. The boundary we have been tracing of the Ldvis formation is here suddenly deflected to a course nearly north for some sixteen or eighteen miles, viz. from St. Claire to St. Vallier, where it again turns north-east, and beyond this it has not yet been defined with certainty. It may be that this apparent unconformity is really a fault which running transverse to the strike brings the Ldvis black slates and limestone conglomerates into contact with a set of strata which lithologically can not in this part well be distinguished from the typical Sillery sandstones of New Liver pool, Sillery Cove, &c., above Quebec, or from those of Acton, Roxton and Granby, which they still more nearly resemble, and which there are some reasons for supposing may occupy a similar unconformable position beneath the Levis formation. The dis- tribution of these sandstones as indicated on the unpublished map of the Eastern Townships very forcibly suggests this idea. Division No. 2 embraces a great variety of crystalline and sub-crystalline rocks ; coarse, thick bedded, felspathic, chloritic, epidotic and quartzose sandstones, red, grey and greenish siliceous slates and argillites, great masses of dioritic, epidotic and ser- pentinous breccias and agglomerates, diorites, dolerites, and amygdaloids, holding copper ore ; serpentines, felsites, and some fine grained granitic and gneissic rocks, also crystalline dolomites and calcites. Much of the division, especially on the south ! eastern side of the axis, i.s locally made up of altered volcanic products, botli intrusive and intcrstratified, the latter being clearly of contemporaneous origin with the assoeiated sandstones and slates. The greatest development of these voleanie rocks appears to occur, as above stated, on the south-eastern side of the main axis, to which I shall presently refer, and about the summit of Division 3, of which they may perhaps be only an upward extension, as we have at present no evidence of any un- conformity between these two divisions. The rocks composing it have hitherto nearly all been included in the Sillery sand- stone formation, and supposed to be everywhere the highest member of the " Quebec group " ; represented by a yellow color on the geological map of Canada and on the unpublished map already referred to. It appears to me, however, that neither their true stratigraphical position nor their geological characters have been correctly defined, and they have, regardless of these, been confounded and incorporated with the true Sillery sandstones, which are only a local development of thick sandstones at several horizons in the Quebec group or fossiliferous Levis formation. At Sillery above Quebec, and at various points thence nortli- eastward to Gaspe, good exposures of these sandstones may be examined, and it has now been shewn that at Little Metis at Ste. Anne (the Pillar sandstones of Mr. 3Iurray's report of I S44) and elsewhere they are ciiaracterized by graptolites and other Levis fossils, whereas in the massive red and green sandstones and slates which are associated witii the volcanic rocks, and which the stratigraphy, as I think, clearly shews to be a lower unconformable formation, no fossils of any description have yet been found. Certain fucoid markiogs in slates near Actonvale may perhaps, however, belong to this division. Further exami- nation will probably afford other fossils, but if so I should expect them to indicate a lower horizon than the Levis formation, prob- ably not far removed from that of the St. John group and the Atlantic coast series of Nova Scotia. In describing this belt of sandstones and slates which extends north-eastward from St. Claire on the Etchemin river, Sir W. Logan writes : " The area over which these strata occur commences in a point near the Chaudiere ; it has been traced to the north-eastward across the Seignories of St. Mary and Joliette into St. Gervaise, and it probably extends much further The distance between this area and its equivalent to the south is about ten miles." w 6 " The sandstones in the two aroas on the opposite sides of the Riviere du Sud are massive ; on tlic northern side they arc often very coarse sprained, and in ironeral of a '. They will, however, doubtless be found to continue till they puss beneath the overlapping Upper Silurii." strata wl . ;i on the Riaiouski Riv' ;• : stated to rest directly on the Ibssiliferou^ Levis form.i- tion. Rocks winch clearly belong to the ' pj cr jt.irt of the division, with associati^d traps, emerge fro'.n beneath the Upper Silurian all along the northern sliore of Matapcdia Lake, and I think it will be found that they extend thence into the Shick- shock Mountains, which on the north ;ire fl.uiked by thi' Levi.^ fossiliferous rocks, and on the .'^outh by strata of Upper Silurian age. The investigation of the structure of these moui.t.iins pre- sents a line tield ior any active and enterprising geologist. The copper ores of the region under consideration, to which too much iu:portancc has, I tliink, beeu attached, in determining the limits of the divisions of the Quebec Group, appear to me to belong to two di yet periods, and to occur under conditions almost, if not quite, as distinct as they do in the Huroniau and " Upper Copper-bearing " rocks of Lake Superior. Tho.se of the first period belong to tiie eryst:illiue, magoesian schist group, and occur both in beds and in lenticular layers parallel with the strati- fication, and also in veins cutting the strata transversely, but in no case accompanied by intrusive crystalline rocks. The Harvey Hill mine, the Viger mine and the Sherbrooke mines are examples of this mode of occurrence. Those of the second period seem to be cheifly confined to the rocks of Division 2, but occur also within the limits of the LtH'is fossiliferous belt. They are in almost every instance more or less closely associated with cer- ^ taiu highly crystulHnc rocks : diorites, dolerites, amygdaloids and volcanic agglomerates, with bands of white, grey and mottled dolomites and calcites which h. ve much more the appearance of great lenticular, vein-like, calcareous masses than of beds belonging to the stratification. No traces of organic forms have been found in them, and yet many of them are scarcely more crystalline than certain Devonian and Carboniferous limestones in which fossils are abundant. The Acton mines, and the numerous openings that have been made in searching for copper ore in that vicinity and in the neighbouring townships of Roxton, Milton, Wickham and Wendover, may be cited as instances of this second class. And it certainly appears as if the copper ore in these upper divisions were in some way connected with the intrusion or segregation of the crystalline rocks which everywhere accompany it. In any case, I think, there are very few who would agree with Dr. Hunt in the general proposition that the diorites and serpentines of the Quebec group are of sedimentary origin, and the amygdaloids altered argillites ; and, unless all contemporaneously interbedded volcanic products are to be considered as of sedimentary origin, the Quebec group might be said to present some of the most marvellous instances on record of ^'■selective nietamorphism.^^ But whether this is so or not, there seem to be no good grounds for assigning either an age or an origin to the cupriferous diorites, dolerites, and amygdaloids of the Eastern Townships different from that of the almost identical rocks of Lake Superior, which Dr. Hunt ^ states have been shewn to overlie uncon/ormahly the Huronian and Montalban series, but which at Keeweenaw Point are stated by Professor Pumpellyf to rest confomiahly on the Huronian; and Prof. Pumpelly justly remarks that '' the question would still seem to be an open one, whether the cupriferous series is not more nearly related to the Huronian than to the Silurian." The same may certainly be said of the cupriferous rocks of the Eastern Townships. Brooks does not, in his paper X quoted by Dr. Hunt, give any very conclusive reasons for his change of views since 1872, and writes altogether as if the question of the unconformable superposition of the copper- bearing rocks on the Huronian were still undecided; and so late as 1877, Professor * 2 G. S. of Penn., Special Keport on Azoic Hocks anil Trap Dykes, §458. I Geo. Survey of Michigan, Vol. I, 1873. X Am. J. of Sc, Vol. XI, 1876, pp. 206-207. Roland Irving writes : the unconformity between the Huronian and the upper copper-bearing rocks " is not certxin^i/ proven.'"-^ A very considerable amount of careful investigation and laborious work in the field is yet required before the indicated divisions can be correctly delineated on the map. The two maps exhibited shew respectively the supposed distribution of the old divisions of Levis, Lauzon and Sillery, and that of the new divi- sions (so far as they have been determined), which I now propose to adopt. These latter have at least the advantage of simplicity ; they also obviate the necessity of invoking any of the numerous almost impossibilities in physical and dynamical geo- logy which are required to explain the previous theory of the structure, and they are, moreover, very closely in accord with the views entertained by Professor Hitchcock as regards the general succession of the formations in the adjoining States of New Hamp- shire and Vermont. Laurentian. — I shall uow make some observations on the results of the recent work of the Survey in unravelling the com- plications of the stratigraphy of the older " cri/stallutes " on the north side of the St. I^awrcnce Valley. Since 1866. Mr. H. G. Vennor, of the Geological Corps, has been occupied in a careful examination of the stratigraphical relations of the Laurentian rocks. His observations, commencing in Hastings county, north of Lake Ontario, have now extended across the Ottawa River, eastward, to Petite Nation and Grenville, embracing a band of country 200 miles in length, with an average breadth of 55-60 miles. Throughout this tract of country, Mr. Vennor has fol- lowed and mapped, in all their windings and convolutions, the great series of Laurentian limestone bands tirst investigated and described by Sir W. E. Logan, in the years from 1853 to 1856, more particularly in the Grenville region, and in 1865, by Mr. Macfarlane, in the Hastings region. The results and con- clusions of all these earlier examinations are given in detail in the Geological Survey Reports. And these shew that the classi- fication then adopted by Sir W. E. Logan was regarded by him as provisional. (See Note, p. 9;j, G. S. R., 1866.) Thus, at the commencement of Mr. Vennor's investigation in 1866, it was supposed that the limestones and calcareous schists of Tudor and Hastings holding eozoon, together with certain •Am..), of S(\, Vol. XIII, 1877. 10 associated dioritic, micaceou-s, slaty and conglomerate rocks, were a newer series than those already examined and described by Sir W. E. Logan, and they were accordingly designated, in the report published in 1870, the Hastings series, and it was further supposed, from its apparent stratigraphical position and from certain lithologieal resemblances, that it might be of Huronian age. The gradual progress of the work, however, from west to east has now, I think, conclusively demonstrated that the Has- tings group, together with the somewhat more crystalline lime- stone and gneii^s groups above referred to, form one great conformable series, and that this series rests quite uncouformably on a massive granitoid gneiss — the gneiss \(i of Sir William Logan's Greuvillo map, publisiied in 18()5, in the Atlas to the Geology of Canada. I wish it to be understood that I have not personally examined this region, and I am therefore expressing the views of Mr. Venuor, from which, however, I have no reason to dissent. Of the actual distribution of this lower or "Ottawa'' gneiss very little is at present known with certainty, though it probably occupies very extensive areas from the eastern shores of Lake Winnipeg to Labrador. And between these same localities there will doubtless yet be found many large areas of the so-called Norian System. The first suggestion of this unconformable Upper Laurentian series, whicli, it seems to me, is intimately connected with the Hastings and Greuville series, appears to occur in the supplementary chapters to The Geology of Canada, 18G8, pages 888-So9 ; but tl.e evidence there given by no means proves the subse(juent assumption of this unconformity ; while the careful descriptions by Sir W. Logan, both in the supplementary chapter above cited and likewise in chapter III, shewing the intimate association and interstratification of the orthoclase gneisses, quart- zites and crystalline limestones with these supposed unconformable L'pper Laurentian anorthosites, much more strongly favor the supposition that they are part and parcel of the great crystalline limestone series. The exhaustive History of the labradorite rocks by Dr. Hunt, in the volume already cited, ^' while giving much valuable and interesting historical information, does not advance us a single step beyond the position taken by Sir W. E. Logan, in 18()3, as regards their true stratigraphical relations. In not one of the • 2nd ti. S. of i'riui., Siucial liciiorf on Azoic Hocks anil Trap Dykes. 11 several areas where they are known to occur in Canada, have they yet been mapped in detail, and even their limits, as indica- ted on the geological map, are more or less conjectural. This appears to be likewise the case as regards the areas where they have been noticed in Essex and adjoining couutits in New York State and in New Hampshire, where Profess r Hitchcock shews that they rest unconformably on the upturned edges of the " Mont- alban " gneisses,'-^ leading to the conclusion that the gneisses of the White Mountains are older than the "Norian," whereas Dr. Hunt, solely, I believe, on mineralogicul considerations, sup- poses these same ^^ Montalhnn^^ gneisses to constitute a system newer than the Huronian. Here then, us in the Hastings reirion, we find theory and experience at variance. But the question suggests itself, may we not have labradorite rocks belonging to systems younger than Laurontian ? Dr. Hunt refers (v^ 318), to the valuable chemical and microscopic examination of these rocks in Essex county, New York, by Mr. Albert Leeds, the results of which are given in the American Chemist, 3Iarch, 1877; but Mr. Leeds does not appear to have studied the stratigraphy of the region, nnd his general conclusions are stated as follows : " That these norites are a stratified rock but have undergone a metamorphosis so profound as to have caused them to be re- garded by Emmons and earlier observers as unstratitied. The dolerites which are formed of the same constituent minerals, and are of the mean specific gravity of these norites, have prob- ably been formed from a portion of these stratified deposits, by deeply seated metamorphic action and have further modified and greatly tilted the superposed rocks in the course of their extru- sion." Prof. James Hall in 18G8f has stated his conclusions that the limestones of Essex and adjoining counties in New York State " do not belong to the Laurentian system either' lower or upper." The facts, on which a part of this conclusion is based, viz. the unconformity of the Laurentian limestone scries to the lower orthoclase gneisses agree with those of Mr. Vennor, and there is, I think, but little doubt that all these crystalline limestone groups — that is those of Essex and St. Lawrence Counties, U. S *Goology of New Hampsliiic, Vol. II, pp. 217-'2]8. t A. J. of S. Vol. XII, p. 298. n^ 12 and Rawdon, Grenville and Hastings in Canada — are parts of one great series, and at present I see no evidence for excluding from this series the associated Norian rocks. Whether the series as a whole will eventually retain the name Upper Laurentian or whether it will be found to be more convenient to designate it Huronian System does not much signify. We can, however, confidently state that this series occupies an unconformable position between a massive gneiss formation below and unaltered Potsdam or Lower Silurian rocks above, and this may likewise be stated respecting the stratigraphi- cal position of the typical "Huronian series" of the Georgian Bay, which together with its close proximity to the western-mosit known exposures of the crystalline Laurentian limestone series which we now know, extends from Parry Sound to Lake Nip- pising, and includes some Labradorite gneiss, renders it very probable that a connection will eventually be traced out between even these supposed greatly different formations, similar to that now, as already stated, proved to exist betv.een the Hastings and Grenville series. Prof. Hall in his note already referred to, states that the La- bradorite formation is '' associated" with bands of cryst:illiue limestone, and further on that the limestones do not belouu to cither the upper or lower Laurentian. He does not however say what the uppjr Laurentian he alludes to is, though in another panigraph we find it stated that the " lower Laurentians are succeeded by massive beds of Labradorite," which we may infer are considered upper Laurentian, in which case there would seem to be, in New York State two sets of L.ibradorite rocks, one associated with the limestones which are '-altogether newer than Laurentian," and another massive and representing upper Laurentian. There is, however, so far as I am aware, no evi- dence of this beinsr the case in Canada. If it is admitted — which, in view of the usual associations of Labrador feldspars, is the most probable supposition — that these anorthosite rocks represent the volcanic and intrusive rocks of the Laurentian period then also their often massive and irregular and sometimes bedded character and their occasionally interrupting and cutting off some of the limestone bands as described by Sir W. Logan, is readily under- stood by any one who has studied the stratigraphical relations of contemporaneous volcanic and sedimentary strata, of paljBOzoic, mesozoic, tertiary and recent periods. Chemical and microscop- IS ical investigation both seem to point very closely to this as the true explanation of their origin. That they are eruptive rocks is held by nearly all geologists who have carefully studied their stratigraphical relations. But I am not aware of any one having suggested that they are the products of volcanic action in the Laurentian or perhaps lower Huronian epoch ; doubtless, as Mr. Leeds says ^'profoundly metamorphosed '^ as of course they would be from having suffered all the physical accidents which have resulted in producing the associated gneisses quartzites, dolomites, serpentines and schists. When we recall the names of Dahl. Kerulf auvl Torrell in Norway, Maculloch and (leike in Scotland, Emmons, Kerr, Hitch- cock, Arnold Hague, and others in America, all of whom consider these norites as of eruptive origin, we may well pause before ac- cepting Dr. Hunt's conclusions respecting them, and that they should often appear as ■' bedded metamorphic rocks" (the opinion expressed respecting those of Skyo by Prof. Haughton of Dublin) is quite as probable as that we should find the mineralogically similar dolerites occurring in dykes and bosses and in vast beds interstratified with ordinary sedimentary deposits of clay, sand, etc. In conclusion I may say that I fail to sec that any useful pur- pose is accomplished, in the present stage of our knowledge of the stratigraphical relations of the great groups of rocks which under- lie the lowest known Silurian or Cambrian ibrmations, by the in- troduction of a number of new names such as those proposed by Dr. Hunt for systems which arc entirely theoretical, in which category we may in my opinion include the Norian, Montalban, Taconian and Keeweenian. These, one and all, so far as known, are simply groups of strata which occupy the same geological interval, and present no greater differences in their physical and minora loa;ical characters than are commonly observed to occur both in formations of the same epoch in widely separated regions, and when physical accidents, such as contemporaneous volcanic action or subsequent metamorpbism have locally affected the general character and aspect of the formation within limited areas. No better instances of such differences could be cited than the Mesozoic and Carboniferous formations of British Columbia and those of the same periods in Eastern America, and the Silurian and Cambrian formations of Australia, Europe and America, u It seems to me that the well-knowQ and recognized names Laurentian Huronian Cambrian and Silurian — with the introduction^ where found desirable, to denote some local break, of the terms upper, middle and lower — meet all pres- ent requirements so far as systems are concerned. Unfortunately in Canndiiin geology, hitherto the stratigraphy has been made subordinate to mineralogy and palaeontology, and as the result we find groups of strata which the labours of the field geologist during the past ten years have now shewn all to occupy a place between Laurentian and Cambrian, assigned to Carboniferous and Upper Silurian in Now Brunswick and Nova Scotia, to the peculiar palasoutological Levis group and its sub- divisions Lauzon and Sillery in the Eastern Townships ; and to lower and upper Laurentian, Huronian, lower Silurian and Trias- sic on the north side of the St, Lawrence valley and around Lake Superior. The same system of miuoralogical stratigraphy is now further complicating and confusing the already quite suf- ficiently intricate problem by the introduction of the new uonien clature I have referred to, and in some cases these names are applied regardless of and in direct opposition to well ascertained stratigraphical facts. A similar unfortunate instance ofpakeon- tologlcal stratigrapliy is found in the history of the Quebec group; and especially in the late introduction in it of the belt of supposed Potsdam rocks, about which T have already stated my opinion. In the reconstruction of the Geological map.of Eastern Canada, — and in this I include the country from Lake Winnipeg to Cape Breton and Labrador — rendered necessary by the present state of our knowledge, I should propose to adopt the following divi- sions of systems to include the groups enumerated : I. Laurentian : To be confined to all those clearly lower un- conformable granitoid gneisses in which we never find interstratified bands of calcare- ous, argillaceous, arenaceous and conalome- ratic rocks. 15 3. 4. III. Cambrian \ II. Huronian: To include 1. The typical or original Hu. ronian of Lake Superior and the conform- ably— or unconformably as the case may be— overlying upper copper-bearing rocks. 2. The Hastings, Templeton, Buckingham, and Greuvillc groups. The supposed upper Laureutian or Norian. The altered Quebec group as shewn on the map now exhibited, and certain areas not yet defined between Lake Matapedia and and Cape Maquereau in Gaspe'. 5. The Cupe Breton, Nova Scotia and New Brunswick, pre-primordi.il sub-crystalline and gneissoid groups. In many of the areas especially the western ones, the base of thi-: is well-defined by un- conformity, but in the Eastern Townships and in some parts of Nova Scotia it has yet to be determined. The limit between it and Lower Silurian is debatable ground upon which we need not enter. The apparent great unconformity of the Nipigon group to the Huronian around Lake Nipigon may perhaps be explained by our having here the deep-seated parts of an ancient volcanic crateriform vent greatly denuded and the crater now occupied by the waters of the lake. The eruptions from this crater may have commenced in the Huronian epoch and been continued at intervals even up to the Triassic period ; but in the meantime we have no evidence of any of the eruptions being newer than Cam- brian. One point I wish particularly to insist on is that -reat local unconformities may exist without indicating any important difference in age, especially in regions of mixed volcanic and sedi- mentary strata, and that the fact of crystalline rocks (greenstones, diorites, dolerites, felsites, norites, &c.,) appearing as stradfied masses and passing into schistose rocks, is no proof of their not being of eruptive or volcanic origin— their present metamorphic < character is as the name implies a secondary phase of their existence, and is unconnected with their origin or original forma- tion at the surface. (Read before the Natural History Society, 24th February, 18V9.)