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D Additional comments:/ Commentaires suppl^mentaires; This item is filmed at the reduction ratio checked below/ Ce document est filmd au taux de reduction indiqu6 ci-dessous. 10X 14X 18X 22X 26X 9m -/ 12X 16X 20X 24X 28X 32X ails du )difier une nage The copy filmed here has been reproduced thanks to the generosity of: Mills Memorial Library McMatter University The images appearing here are the best quality possible considering the condition and legibility of the original copy and in keeping with the filming contract specifications. Original copies in printed paper covers are filmttci beginning with the front cover and ending on the last page with a printed or illustrated impres- sion, or the back cover when appropriate. Alt other original copies are filmed beginning on the first page with a printed or illustrated impres- sion, and ending on the last page with a printed or illustrated impression. 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Tous les autres exemplaires originaux sont filmds en commenpant par la premidre page qui comporte une empreinte d'impression ou d'illustration et en terminant par la dernidre page qui comporte une telle empreinte. Un des symboles suivants apparaitra sur la dernidre image de cheque microfiche, selon Ie cas: Ie symbols — ^ signifie "A SUiVRE", Ie symbole V signifie "FIN". Les cartes, planches, tableaux, etc., peuvent 6tre filmds d des taux de reduction diffdrents. Lorsque Ie document est trop grand pour dtre reproduit en un seul clich6, il est filmd 6 partir de Tangle sup6rieur gauche, de gauche 6 droite, et de haut en bas, en prenant Ie nombre d'images n6cessaire. Les diagrammes suivants illustrent la mdthode. rrata to pelure, n d D 32X 1 2 3 f. Skotion IV, 1887. [ 63 ] Trans. Hoy. Soo. Canada. VI. — The Correlation of the Animikie and Haronian Rocks of Lake Superior. By Peter McKellab. (Communicated by Dr. Bell, May 25, 1887.) Having had more than twenty years experience, as a practical geologist, among the rocks of nearly every district on both sides of Lake Superior, I may be allowed to offer to the Koyal Society the results of my studies of the relations which the different formations of these regions bear to one another. A want of agreement has lately arisen among geo- logists, as to the equivalency, or otherwise, of the Animikie and the Iluronian series of this part of the Dominion, and I propose to confine ray remarks chielly to an elucidation of this problem. I think I am in possession of suihcient facts to set at rest any question as to their mutual relations. The term " Huronian " was first applied by Logan and Murray to a set of metamorphic and igneous rocks north of Lake Huron, and the name was soon extended to rocks, similar to the majority of these, on Lake Superior. Sir William Logan also called the Huronian, the " Lower Copper-Bearing Rocks," and th'j series of which the Animikie forms the lower part, the " Upper Copper-Bearing Rocks" ol Lake Superior. What is considered to be the equivalent of the upper division of this h.tter scries on the south shore of the lake was afterwards called the " Keweenian " formation by the United States Geologists, the name being derived from Keweenaw or Kowaiwana Point. Logan's names — Lower and Upper groups of the Upper Copper-Bearing Rocks of Lake Superior — were found to be iuconA'enieutly long for constant use, and Dr. Bell proposed to call the whole series the "Nipigou" formation, it being extensively developed around Nipigon Lake and the Bay of the same name on Lake Superior. The lower and upper groups of the Nipigon (or Upper Copper-Bearing) formation appeared, from Dr. Bell's descriptions, to be unconformable to one another, and Dr. T. S. Hunt, at the suggestion of the writer, proposed the name " Animikie " for the lower portion — Animikie being the Outchipwai name for " thunder," the formation being well developed around Thiinder Bay. The name "Nipigou" would then be restricted to the upper division. The sandstones of Sault Ste. Marie are generally conceded to be newer than any of the formations referred to, although their relations to some of them have not yet been very satisfactorily demonstrated. According to the Canadian geologists, we have therefore, on Lake Superior, the following sets of rocks, in descending order : — 1. The Sault Ste. Marie sandstones, resting apparently unconformably on the Ke- weenian. 2. The Nipigon formation, equivalent, at least in part, to the Keweenian. 3. The Animikie formation, unconformable to both the Nipigou above and the Huronian below. 4. The Huronian system. , c^ iT l*-vw< '<^\---<.A^ ^ ^-«^-# /yLi*i/^ i ^-J.^oc - ^^K4^ -.--V^-v'ttWwv» ^■^■^^VisX "f^< v-S-v*v*, /CH..-V/ HUKONIAN HOCKS OF LAKE SUPEKIOK. 68 tv u: In regard to tho Luko Superior region, it seems to me an easy matter to prove the muonformability ol'the Aniinikio formation with the Ilnronian system, as laid down by Dr. Bell, and with the I'olded schists of Trot. Irving. The latter gentleman, in his interesting and excellent rei)ort on the Archivim Ibniiations of the North-western States for 1885, admits that the fuUled schists of the Marquette and Menominee districts, as well as those of the north shore of Lake Superior, or a great part of them, are Huronian. He then tries to show that they are the equivalents of the Animikie formation. lie states (p. 20(3) in reference to the Lake Superior Huronian of Dr. Bell : — " Accepting, for tho time, some of them as Huronian, wo are immediately confronted with a structural problem of a good deal of dilficulty, i.e. the relation of these folded schists to the unfolded Animikie s(M'ies. Generally, as the Animikie series is tra(!ed towards its northern border, it is found to li" against a belt of granite and gneiss. This is so along the shore of Thunder Bay and thence westward to Gundint Lake, is true again at thts Mesabi IJange and Pokegoma Falls district, in Minni'sota. North of this belt of granite again come the belts of i'olded schists. The appearance thus presented is at first siu'ht one of general unconformity between the llat-lying Animikie and an older series, including the gneiss and i'olded schists. But a clo.se studv of the folded schists indicates, as has already been shown by Bell, Chester, Winchell, and myself, much litho- logical similarity between portions of them and the Animikie series, so that a difl'erent structural hypothesis at once presents itself to the mind. This is the one that I have elsewhere illustrated and explained. The hypothesis is, briefly, that the Animikie rocks were once continuous with the folded s of the Iluronian slates. Tlie clay slates of the Iluronian are rarely, if ever, l)lack in color, except in the case of an occa- sional thin stratum of plumbaginous or carbonaceous schist twenty to fifty feet wide. This schist may be seen on Location 14 M. east of Steel Tviver; it is widely different from the black slates of the Animiki(>. Tlie Animikie clay-stones are often micaceous, the mica showing in silvery-looking scales. In the vicinity of the silver mines, east of Whitefish Lake, and again at Sawyer's I>ay, Thunder Cape, and many other places, the scales are small and spareely distributed over the partings. In other places they are from one quarter to halt an inch in diameter and plentiful, as for instance, in the mountain-face, east of Blende Lake in McTavish Township. Here the black, coarse and fine slaty argillites are largely develo[)ped, underneath tlie Nipigon or Keweenian sandstoni's. In all these slates the min, are to a great extent eharac- terisod by a peculiar internal oolitic structure, such as I have not seen within the Tluro- uian rooks. I have noticed this feature along the strike of the j'orniation I'or over one hundred miles, or from Silver Lake to Gunllint Lake. Again, none of the chloritic, talioid, actinolitic, micaceous, or dioritie schists, that are .so plentiful in the lluronian folded schists, are found among (he Aniniikie beds ; nor are any of the obscure conglomerates, so plentifully developed throughout, and so charac- teristic of, the lluronian of Lake Superior, to be seen in the Animikie. These eonglo- merates or agglomerates, which arc ni .de up of oblong or lenticular masses of various sizes, from a few inches up to twenty i'eet and more in length, are generally arranged parallel with tho bedding. Usually they are thickly packed, and show a gradual transition from the massive central nucleus to the more lissile si'histo.se matrix, the latter being also deeper or darker in color, than the former. It is only on weathered, smooth, wet surfaces that they arc well seen. They have been described by Logan, Bell, Macfar- lane and others, and different theories have been given for their formation. The rocks of the Animikie group, as a general rule, have a tendency to break at right angles to the biidding, while the lluronian rocks show a strong tendency to l)reak at acute angles into lenticular I'ragments, characteristi<' of crystalline .schists. The Animikie strata are consjucuously slaty or llaggy, not schistose ; and the lluronian rocks are as conspi- ci;onsly schistose by reason of the development within themselves of leafy minerals. Again, with the exception of the crystalline trap, chert, dolomite and iron ore, the constituent minerals of tht^ remainder or major portion of the Animikie strata are frag- mental, and of exoti(' origin as shown above in the case of the mica in the clay-slate. Those of the lluronian rocks, on the other hand, have been developed in place by metamorphism. The trap, of course, was crystallised from the molten state. The cherts, jaspers, dolomites and iron ores, have proba])ly be(>n chemically formed, as suggested by Prof. Irving and others. In the lluronian i'olded schists, chlorite, mica, hornblende, etc., in fim^ grains, are plentifully developed in places, constituting great thicknesses of the difl'ereiit schists characterised by these minerals, while in the Animikie, I believe, none of these minerals are developed Avitliin tlie sedimentary beds, except perhaps in close proximity to eruptive trap. It would appear that (he Animikie strata are not suiriciently metamorpho.sed for the differentiation of thes(^ minerals. The prevailing greenish aspect of the lluronian folded .schists seems to be caused by the partial development of a chloritic ingredient as shown by Prof Irving. When des- cribing (p. 221) some of the typical lluronian strata, he states, "Most all of the kinds, ex(n'pt those that are nearly purely (juar(zose, have undergone a considerable amount of metasomadc change, the principal result of which has been the production from the feld- spars of chloritic ingredients ; whence, chiefly, the dark and often greenish hue presented by these rocks." This dark and greeni,sh hue is a prevailing characteristic with the bulk of the lluronian strata, and is entirely absent from the Animikie. This distinguishing feature alone should, I think, be suflicient to separate the two formations, especially as it is so marked, and where only a line, as it were, separates them for some two hundred miles or more along their northern contact or boundary. 68 McKRLLAR ON THE ANIMTKIR AND STUATUtnAriiiOAL STmiCTTiRE.— In the rorcuroiiii? piigi's, I think I havo shown that thore is a Htroujrly marki'd litholojriial (liirt'n'iict^ hotwocu the almost horizontal and nnaltorcd Aniniikii' and tho folded crystailinn Ilaronian scluNts of Lake Superior. Now I will t'ndi'avor to piovc by stratii^rajjliiial cvidciitc that tin' diircrcnct! is condusivt'. Prol'. Irvinj^ shows that tho Aniniikit' l)t'ds on the north shore oi' Lake Superior and the renokeo-Oon[ebi(! beds of tho south siiore, in Wisconsin and Michigan, belong to the same horizon and that wherever they are exposed, with tho exception perhaps of tho Knife Lake area, as on the south shore, aionj; their strike for some sixty miles, and on the north shore in thi> same way, from Tiuuidir ])ay, to Mississippi River, a stretch of over two hundred miles, they present a simple Hat, l)edding with a moderate dip, always towards the great basin of Lake Superior; and that their position, as far as known, is always next underneath tho Keweenian group, which agrees precisely with the condi- tions of the latter or overlying group in relntion to the Lake Superior synclinal. He shows also that the I'olded schists of the north shore and those of the Marquette and Menominet^ districts are the same formation and that they are characterised by irregular, stoop, complex cleavage or bedding, conspicuously dillerent JVom the simple flat bedding of tho An'mikie rocks, all of which, I think, no one can doubt ; at least it agrees com- pletely with my knowledge of the two formations. But when he claims in his hypothesis, that this broad simple trend of the Animikie under th(> Lake Superior basin remained undisturl)ed at the time of the steep folding of the Iluroniaii, I cannot agre-j with him. It seems clear, and 1 think Prof. Irving's own showing conlirms it, that the Animikie and Keweenian strata must have been comi)aratively level during the building up ot tho latter fornuvtion, whicii is now seen on both sides of the lake dipping towards each other underneath the Lake Superior basin. Therefore, tho sinking of the strata in the middle of tho lake must have taken place after tiie l)uilding up of the Keweenian group, and before tho deposition of the now flat-lying Sault Ste. Marie sandstones. The once molten matter, which constitutes the bulk of the Kmveenian strata, must have presented a tolerably level surface over this vast area, at the time of the solidillcation. It seems plain that tho broad geological downward bend or synclinal that forms tho geological basin of Lake Superior, could not havo resulted concomitantly with the close folding of the Huronian strata, as inferred by Prof. Irving in his hypothesis. No one, I think, will claim that tho folding of the Archiran strata occurred after the building up of the Keweenian group. I have traversed, in considerable detail, almost all the Huronian folded schist areas lying between Mii hipicoten and Lake of the Woods. I havo seen tho Marquette schist- formation and spent a good deal of time in examining the folded schist-belt on tho South Ilango?, south of tho Keweenian or Native Copper Range lying to tho south of Ontonogou, Michigan. I have found the majority ol' the strata of each of these areas to present strongly the Huronian greenish chloritic aspect previously mentioned. I have also found those strata almost invariably highly inclined or nearly vertical, and associated with gneiss, syenite and granite ; often iuterstratified with and intersected by tho latter two, in which relation the Animikie strata are never found. This bolt of chloritic and greenstone schists occupies the greater part, if not the whole of the south half of Town 40 N. in Range 3'J and 40 W. These schists stand on edge or arc highly inclined, striking eastward across tho middle branch of Otouagon River towards HURONfAN llOCKH OF LAKK SUIMIRIOR 69 Mnrqiu'lto iintl wostwiird iicross the Wisconsin houmliiry. On tlic north, they are bonndod by course j^ninitcH whicii occupy the nortli slope of the range juul on the south, in Town 4'), they pass into micaceous and hornhh-ndic gneiss that carries gohl in the inclosed qunrz veins. No d()ul)t these schists are a continuation of the Marciuetto and Meno- menee schists. But I shouUl he greatly surprised if they can l>e shown to he the (U)n- tinualion of the I'enokee-Clogehic Mat shites, as would appear hy the arguments and the map of Prof. Irving. I mean hy the l'enoke(^-(rogel>ic hclt, the Gogebic bi>lt of slates in which tht^ Colby Iron Mine is situated, ndbre seeing I'rof. Irving's report, I was under the impression that the rocks of the Penokee Iron I{ange were like those of Mar- quette, and those of the riogel)ic Iron Kange like the Aniniikie rocks. From all the known facts, it seems certain that the Animikie and Keweeniau groups together, form the bottom of the great geological basin of Lake Superior, which covers an area of about 30,000 square miles. Theses strata show a moderately low dip towards the middle of the lake, but l)ecome steeper on the south side than they are on the north. They cover nearly the whole bed of Lake Superior, as niiiy lie seen by the exposures on the inlands and main shore. From the broad part or middle of the lake — say, from th(^ meridian of Passage Island, they strike inland one both shores, and with a breadth of one hundred and fifty miles, they oontiiuu! west-south-westward for more than two hundred and lil'ty miles — or nearly, if not (|uite to Mississip[)i liiver — leaving a tongue of the old rocks, from the west, to penetrate ])etween them to the end of the lake at Dululh, as will be seen by Irving's map. The Archiean rocks, named the " Laurentian gneiss " and " lluroiiian folded schists," wherever seen on either side of this great basin are almost invariably highly inclined and uncoiiibrmal)le to the comparatively undisturbed strata referred to. lUit, as would naturally be the case, with a basin or depression such as this, the strike of these two sets of strata (though not th(> angles of the dip) along the sides would be likely to agree very nearly, which is the actual condition presented, as may be seen on the south side along the South and Gogebic Ranges, and on the north side along the liiu? of contact from Thunder Bay westward. Tiiis aiiparent agreement of the strike of the two sets of strata would render it the more dillicult to detect unconformability between them, especially us an unstratilied member of the Archtean rocks almost inva- riably presents itself next the flat strata of the Animikie series. These conditions exist in the only portions of the contact examined l)y Prof. Irving. But from Thunder Bay eastward, this conformability of strike no longer continue.';, as nniy be seen north-east of Thunder Bay and at Black and Nipigon Bays, where the llat-lying strata of the great basin referred to make a deep impression northward across the general strike of the nearly vertical folded schists and gneisses. This general want of conformity may be again seen along the north shore, south-eastward and diagonally across the strike of the y\rch;ran rocks, from Nipigon Bay to Sault Ste. Marie. Along this part of the coast, great belt.s — miles in width — of the Hixronian folded schists, standing on edge, stiike into the lake towards the flat basin referred to, and presumably they continue underneath the Animikie group. As for instance, the schists of Michipicoten Kiver, Homer Township, Pic and Steel llivers, Nipigon and Thunder Bays, all of which strike into the flat geological basin referred to. The Slate Islands are situated ten miles from the shore, opposite to Steel River. These islands are occupied by folded Huroniau schists, standing on edge, running east 70 MeKKLLAR OX TIFK ANIMIKIR AND iiiul west unci moasurinj? over live tnilfs lu-ross thu strike. They nrc iiilcrcc'ptt'd ut i\w HO>i(h-vv»'st ansl<^ of tlm livrp- islaml l»y thf uiiconlormahlc Aiiimikin iiiul Kcwcciiiiui hcdN, wliiih occupy the shore lor alioiit three {|uarter8 oi' a mile. The Keweeiiiau ainyff- (laloitls, Iniver.sed hy (|uartz vciu.s, carryi.ijr native copper, dip S.S.W. at an anv'Io of tlO to 7'") lioiii the horizon. Immediately l)ehind them, the I'erru'^Mnou.s cherly l)eds of tlie Animikie astward through the gaps or basins above referred to and under- neath the tlat-lying Keweenian })cds. They must, I think, continue eastward across Black and Nipigon Bays, underneath the two Hat-lying groups, i.e. the Keeweniau and Animikie, and they are no doubt the same as those which appear on the shore to the east of the latter bay. At the outer basin, eight to ten miles from the bay, the rough and uneven surface of the old rocks has attained an elevation above Lake Superior of from *700 JIUHONIAN liOCKS OF LAKK HUI'KUIOH. 71 to 800 ft't't. II(>ro, rcstiiiiy upon it, are to be kcch cnly the trappt'aii bods of thoKcwooniiin group, with 11 low (lip rusl-soutli-ciiNlward. Fu the iifxt Imsiii, livi- to tJi'Vt'ii iiiili-M iVoiii tliL' l>uy, tlic jniluralcd raiiils uud suiidstoni! in'ds ol tin- Ki'Wiruiuii group iipi)i'ar uuder the trappi'iin ht'dH. liow down, within two or three miK's ol'tho hay and alxxit three to lour niih'N south of Woir liiver, I Naw l)hi'k-lo<)l\iiitj Nat shiles. which I think niuwt he Aniii.ilvie. F have not heen in tliat lorality lor years and wouhl not he sure ol' this point. 11' Aniinihie, it would he interesting; to traee out the rontact with the Keweenian heds. Within tliese hasiuH and all around this locality, iho folded schists, the granites and the ifneisses stand vertically or nearly so, and must have heiMi eroded and planed down to a great depth hefore the deposition of the overlying Hat heds, whether tiie ver'icalily of the strata was caused by folding or by faulting. Again, in McTavish Township in the vigor Townshii), is in the lluronian greenstone-schists formation, and the Silver Harbour Mine in the Hat Animikie slates, both locutions adjoining. The line of contact of the two formations is covered, but on approaching it. they show no change in their regular dips, whit<'., with the nearly vertical Huronian strata underlying them ai a depth of about live hi;ndred feet, while the surface-contact of the two formations lies to the north about one )nile from the works. The shaft-sinking, and the deep borings made at this mine with the diamond drill, actually atl'orded direct proof that the horizontal and unaltered shales, etc., rest immediately on Huronian syenite and on the upturned and denuded edges of tho crystalline schists of this series. The folded schists with associated g.anites and gneisses are highly inclined or ver- tical, in the vicinity of Thunder Bay, as is the case with them generally ; while the Animikie beds, on the north shore, are, with rare exceptions, Hat or slightly inclined. We find patches or outliers of the Animikie beds in their usual Hat position, resting on Iii 72 McKliLLAK ON TRK ANLMIKIE AND the old rocks, somotimos half a mile or mere from the general lino of contact, as, for example, behind Amethyst Iliirhonr. Near the foot of Thunder Bay, the line of contact of the two formations trends north- ward across the strike of the Iluroniun green schists to the granite range lying abont Jive miles back from the bay. Along this line, the two formations are dovetailed into one another for miles. In some cases, the dovetailing is caused by faulting, as for example, along the Blende Lake vein, and along the great Silver Lake fault. The latter causes the slightly-inclined Animikie beds to overlap the vertical Iluronian strata on the north side of the i'ault, for a distance of three miles or more. TJie overlying Keweenian l»eds of sandstone and marl overlap the Iluronian crystalline schists for over a mile. The conglomerate bed at the base of the Keweenian group is well exposed on the north side of the fault in the cutting on the Canadian I'acific Iinilway near the west end of Loon Lake, while on the south side, (he same bed is exposed east ef the Silver Lake Iron Mine, within fifteen or twenty chains of Silver Lake. CoNT.\CT OF THE Animikie .4NI) Keweenian Form.ations. — Geologists have expressed different views as to the correlation of these formations. I shall here give a few facts relating to this question, which have come under my own observation. I have, in one instance, traced the contact of the Keweenian with the Animikie, which is exposed at intervals, from Lake Superior, near Silver Islet, to the great Silver Lake fault in McTavish Township, a distance of al)out twenty miles. It starts from the \vat(>r-level, a little east of Silver Islet, and winds around to Sawyer's Bay ; thence, northward, along the west- facing escarpment to the fault above mentioned, at a point about fifteen or twenty chains west of Silver Lake. Here the line of contact has attained an elevation of probably five hundred feet above Lake Superior. All along, it shows a bed of coarse conglomerate, becoming coarser to the north and varying in thickness from a foot to thirty feet or more, and lying between the gritty white sandstones of the Keweenian and the underlying and much more altered strata of the Animikie group. The two formations, which ar(! apparently conformable, dip at a low angli> east-south-eastward. There seems to be a dislocation along the foot of the e.si'arpmcnt, extending probably into Thunder Bay, which has brought the lower members of tlie Animikie group on the west side against the clay-slates on the east side. The l)lack clay-.slates, seen underneath the conglomerate bed, for the most of the distance thence, are replaced at Iron Lake, twenty chains south of the great fault, by soft, grey, thin clay-slates which show a thickness o ' about seventy feet, underneath the sandstones. It is caused, no doubt, by faulting of the lower forma- tion at a point further south, where it is not exposed. Some three or four hundred feet to the north of Iron Lake, a dislocation of Animikie age brings the ferruginovis chert and jasper beds into position next underneath the conglomerate and sandstone beds; and they continue in this relation northward to the Silver Lake fault. At the Iron Lake fault, which brings the jasper rocks into the above position against the clay-slates on the south side of the fault, the overlying Keweenian beds continue across uninterruptedly, showing that a large amount of Animikie strata must have been denuded away before the depo- sition of the Keweenian beds. Aliout a mile or two soiith of Iron Lak(>, I saw places where deep erosions in the black clay-slates were filled in and levelled up to the overlying sandstone with coarse couglo- IIURONIAN ROCKS OP LAKE SUPERIOR. 73 merate material. At Sawyer's Bay, tho Animikie strata corresponding to those exposed on the south-west side in tho high part of Thunder Cape, appear to me to have been denuded away to a depth of nearly 1,000 feet, or to their present level beneath the Keweenian strata on the east side, instead of having been brought into that position by a dislocation as geologists have generally supposed. In conclusion, I would state that it appears to me that the Laurentian gneisses and the Huronian schists of Lake Superior were together involved in a grand disturbance of the rock-formations, which resulted in a general upturning of the strata, and that there had also been a general levelling down of these rocks before the Animikie age. Again it appears that after the deposition of the Animiki(i formation, geological changes took place without causing much alteration of level, in the course of which the strata were dis- located in many places and afterwards eroded and levelled down to a considerable extent before the commencement of the Keweenian age ; and again, as before stated, that the sinking of the Lake Superior geological basin took place after the building up of the Keweenian group, and before the deposition of the Sault Ste. Marie sandstones. It seems probable, that the sinking of the Lake Superior basin was the only event which separated these two formations. Sec. iv, 1887. 10