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CANADA DEPARTMENT OF MINES GEOIXMHGAI* SDl^VBY •trmf^i^-tfmmm tMMKwmtSTl No. If, Gmmokal Espaiu^ District, Ontario iT.QoMw OTTAWA No. IfiM CANADA DEPARTMENT OF MINES Hon. a. SivioMY, Actino Mivistbk: R. G. McConkbll, Dbputy Minim » GEOLOGICAL SURVEY William McInnes, DiaecTiNc Geologist. I MEMOIR 103 I No. 85, Geological Semes Espanola District, Ontai^o BY Terence T. Quirke 29249c UTT.'VVVA lENT Printisg Bureau 1917 No. 1694 OONTENTS. CHAPTER I. latraductioa Gmnl lUtMatnt aad ■dmewMciMMs. ir>*i Ml and crc« rauTpo^ n •ih' eommimicmtioii P»*vto' ' V j,« AgrictiKure •nc' iumbtring Tofwgnpby CHAPTER II. Sammary Tabit ot formatioiM. CHAPTER III. Phyiiography Origiii of clifft and canyoaa. CHAPTER IV. Stratigrapby Pre-Huronian Sedimenu Distribution Stratigraphic relatkMia Character Micaceoua alate or phylUte Micaccoua achiat or greywacke achiat Suurolite achiat Quartiitic achiat Baaic intruaiona Granite Age and rebtiona huronian Bruce aeriea MiaaiMagi quartaite Diatribution Character Thickncaa Origin Bruce conglomerate Stratigraphic relational Diatribution Character Origin '^sponola group Bruce timeatone Stratigraphic relationa , Diatribution Paai 1 I I 1 3 3 4 9 12 10 19 19 19 19 19 20 20 20 21 21 22 23 24 25 25 25 25 28 28 28 28 29 30 i? 33 34 34 34 8 Page Character and thicknew 35 Origin 35 Espanola greywacke 35 Stratigraphic relations and distribution 35 Character 35 Thickness and origin 36 Espanola limestone 36 Stratigraphic relations and distribution 36 Character 36 Thickness and origin 38 Serpent quartzite 38 Greywacke member 38 Stratigraphic relations and distribution 38 Character 38 Thickness and origin 39 Quartzite member 40 Stratigraphic relations and distribution 40 Character 40 Thickness and origin 42 Cobalt series 42 Gowganda formation 43 Stratigraphic relations and distribution 43 Character 43 Slate member 47 Conglomerate dykes 47 Microscopic determinations 47 Thickness and origin 47 Keweenawan diabase 49 Distribution 49 Character 49 Microscopic determinations SO Quartz diabase 50 Diabase 51 Olivine diabase 51 Gabbro porphyrite 51 Contact metamorphism 51 Absorption 51 Microscopic determinations 52 Quaternary 55 Glacial 55 Post-Glacial 55 Lake sands 55 Stratified clays 56 Marlekor or imatra stones 56 CHAPTER V. Structure 59 General structural conditions 59 Summary of events 59 Field data 61 Overthrust faults 61 Page Minor faults 62 Thrust faults 62 Mechanics of the postubted movements 64 Character of the stresses 64 Physical nature of the members involved 64 Shape of the members 65 Applications to the Espanola structure 67 Assumptions 74 Facts in conclusion 75 Index 89 Illustrations. Map 180 A. No. 1624. Espanola area, Sudbury district, Ontario in pocket. Plate I. A. Skyline from a hill near Webbwood looking north 77 B. Decadent cliff on the shore of Moon lake 77 II. A. Typical outcrop of Bruce limestone 79 B. Solution hemispheres in Espanola limestone 79 III. A. Ripple-marks and mud cracks in Serpent quartzite 81 B. Pebbly, quartzitic dykes cutting Espanola greywacke 81 IV. A. Serpent quartzite showing the lining due to feldspar and quartz laminations 83 B. Post-Glacial, interlaminated clay and sand deposits 83 V. Marlekor or imatra stones 85 VI. A wooden block compressed in a direction transverse to the grain 87 Figure 1. Location of Espanola area 2 2. Diagrammatic section of formations in Espanola area 8 3. Diagrammatic section of Gowganda formation of the Cobalt series, Foster township 46 4. Generalized cross section of Espanola area 60 5. Flexure of column: (a) With fixed or square ends. (b) With rounded end. (c) With one fixed end and one rounded end 66 6. Idealized section of the deformed Huronian terrane 68 7. Supposed lens shape of Bruce and Cobalt deposits before deformation. 70 8. Hypothetical structure of Huronian formations at Espanola at the time of: (a) First thrust fault. (b) Second thrust fault. (c) Third thrust fault. (d) The overthrust fault 73 Espanola District, Ontario. CHAPTER I. INTRODUCTION. GENERAL STATEMENT AND ACKNOWLEDGMENTS. The following report is an account of the geology of a small area in the neighbourhood of Espanola, Ontario. The field work was commenced during the summer of 1914 by W. H. Collins of the Geological Survey of Canada, this area being one of a series of key areas which were to be studied with the object of correlating the geological succession at Sudbury with that of the classic "original Huronian" district near Sault Ste. Marie. A preliminary report on this larger problem has already been published.' After two weeks' work in Merritt township the geological investigation of the Espanola area was delegated to the present writer. Valuable assistance was given by John R. Marshall and E. W. Todd, who mapped many of the lakes and roads of the area, and by the writer's fellow geological assistants, W. E. Cockfield, H. J. Heath, and Arthur Benoit. Grateful acknowledgments are due Professors R. D. Salis- bury, A. J. Johannsen, and R. T. Chamberlin of the university of Chicago for many suggestions and criticisms. LOCATION AND AREA. The position of Espanola area is shown in Figure 1. The area mapped is 16 miles long from east to west, .^nd 7i miles wide, having thus an area of 116 square miles. It includes all of the townships of Foster and Merritt, two-thirds of Hallam, and a strip IJ miles wide across the south side of Shakespeare, Baldwin, and Nairn townships. TRANSPORTATION AND COMMUNICATION. The area is readily accessible. Espanola station, on the Soo bra»:ch of the Canadian Pacific railway, is 43 miles west of Sudbury, and Webb- wood is 5 miles farther west. The Algoma Eastern railway traverses Merritt township from north to south, the stations of Espanola Mills and Merritt being near the north and near the south end of the district respectively. There are several good highways in Hallam township, including the trunk road between Sault Ste. Marie and Sudbury, which ■ ColUiM. W. H., G«oL Surv., Can.. Mu*. BulL No. 8, 191«. § u3 o s .S iZ runs through the northern part of Hallam and Merritt townships. Foster township and the southeaster i part of Merritt township are without any roads except a few "tote" roads which h .e not been in use for mony years. Vermilion river crosses the northeastern part of the area to join Spanish river on the boundary between Foster and Merritt townships. From that point Spanish ri , .-r continues in a westerly direction across the northern part of the dist. ict. There is also a good canoe route from the mouth of Vermiiion river, through Brazil, Elizabeth, and Augusta lakes into lake Panache. PREVIOUS WORK. The townships of Merritt and Foster are in Sudbury mining district, and were mapped in the southwest corner of the Sudbury sheet;' in his report on that district R. Bell' made no mention of the Huronian rocks near Espanola. For the Ontario Bureau of Mines, Dr. A. P. Coleman' made a reconnaissance trip, apparently chiefly along the railway, during the summer of 1913. The southeastward continuation of the formations fGjnd at Espanola north of La Cloche mountains, has been repwrted upon by Bell in the French River report.* In his report on the Sudbury mining district. Bell has also described the out'jrops around and south of lake Panache.' The rocks south and southeast of Espanola have been described again by Coleman.' In his preliminary report, Collins' has stated for the first time the succession and correlation of the Espanola formations. AGRICULTURE AND LUMBERING. There are a few small farms in the less rocky parts of Merritt, Bald- win, Hallam, and Shakespeare townships, but, since they are nearly all on a sand-plain they are not very productive. The towns of Webbwood and Espanola Mills have populations of a few hundred people apiece. At Espanola all the people derive their living from the Spanish River Pulp and Paper Mills. This company has a head of water o' 62 feet at its dam, although the natural fall was less than 20 feet. The waterfall was formed by the Spanish river cutting through lake deposits down to a diabase dyke. The mills enable the local settlers to dispose of their timber profitably. In earlier days the whole sand-plain was co\ cred with spruce; of that forest only stumps remain. The pulp mills at Espanola 1 Geoi. 3urv,. Can., geological map of Subdury mining district, Sheet No. 130. ' Bell, R., Geol. Surv., Can., Ann. Kept., vol. V, l.SSO-OO, pt. F. ■Coleman, A. P., Ont. Bureau of Mines, 2M .\iin. Rept.. 1914, pp. 221-222. 'Bell. R., Geol. Surv.. Can., .^nn. Rept., vol. LX, pt. I. p. \9. f Bell, R.. Geol. Surv., Can.. Ann. Rept., vol. V, IKfiO-OO, pt. F. • Cole., an. A. P.. Ont Buieau of Mines. 23d Ann. Rept.. 19U. pp. 219-221. 'Collins, W. H., Geol. Surv., Can., Mus. Bull. No. S, 1914, pp. 13-14. take all the spruce which is btx>ught in from the surrounding country TOPOGEAFHY. As aTLlhS?^? w^ formerly mature is now in the rejuvenated stage. As a result of Pleistocene glaciaUons the rountry now abounds in chS ^^'.'^nvV^'"''^^'^'' °'^ '^^ «^^ ^°^™«J '-^ the po'tiSai stages of lake Huron. There are many lakes in the district If a Une were drawn from the northeast corner to the southwelt Sjrner of the area, nearly all the lakes would lie on the south sidfoTtheTe NoS .l-^i ?• , T ^5°" ^^* ''"^'^"^ °^ sand-filled valleys. The baS M^." 'I^u'' '"^ ^""^ ^" "'^^ ^« «^"^« "°™al at valley itto^ bold and strilang h.lls, but in general, the relief is less than 300 feet Tnd the dramap .s very youthful. The hills rise to an evident ac^^rce of summit levels, and many of them are flat topped accordance CHAPTER II. SUMMARY. This district is part of the eastward continuation of the "Original Huronian area," and, for the most part, its rock formations belong to the Huronian system. There are also older basement rocks consisting of much metamorphosed sedimentary schists and slates, and intrusive greenstones and granite, collectively referred to hereafter as pre-Huronian. In most areas where it is known, the pre-Huronian series of sediments is cut in many places by acid intrusions, but, in this particular area, granite is found only in the northwest corner at a distance from these sediments. The sediments are said to be traceable here and there into the typical pre-Huronian formations of Sudbury district. They are thought, therefore, to be equivalent in age to the Sudburian series of Coleman' and possibly to the Temiskamian of Miller and Knight.* Overlying these ancient and greatly metamorphosed schists and greenstones, and in faulted contact with them, are two series of steeply tilted, and in many places faulted, Huronian sediments. These are part of sediments on the north shore of lake Huron which have been described most recently and differentiated by Collins.' ^ 'allowing the nomenclature proposed by Collins, the writer will ? 1. ver of the two associated series as the Bruce, and to the ■•;■■: , "obalt series. In the Espanola area, the Bruce series is kZ . ■ ■ ' the Mississagi arkose and basal conglomerate, the Bruce congloi ., the Espanola group (which includes the Bruce limestone, the Esp :ola greywacke, and the Espanola limestone), and the Serpent quartzite. In the Cobalt series, there are slate conglomerate, beach-like conglomerate, and well-bedded, clean slates, which are classified x)l- lectively as the Gowganda formation. The Cobalt series is uncon- formable upon the Bruce series. The Huronian rocks are cut by a series of diabase dykes and sills which characterizes the whole region. Fortunately these injections do not occur so abundantly that they prevent a determination of the sedimentary succession. They seem to have come later than the faulting near lake Tulloch, in the Espanola area, but in other parts of the Timis- kaming region — specifically, near Algoma station — it is evident that some of the faults cut some of the diabase injections. It is likely that the I Coleman, A. P., "The nickel induitry," Mine* Branch, No. 170, Ottawa, 1913. > Miller and Knight. Ont. Bureau of Minn, vol. XXII, pt. II, 1914, p. 127. • CoUini. W. H., GeoL Surv., Can., Mu*. BuU. No. 8, 1914, p. 26. diabase injections and the faulting were «,«« . and that they are kindred prJSluc^oJZ ZZ^ ''" ~ntemporaneou. TL r . . "viui-iB ui me same Darenf r-nnoo at the time of rupture Thes^^fauLT'^'"^ '° ''"^^ ^^" -southward have stratigraphic throws up to i^^.T 'Z^J^ *''^"*^ '-''«' ^J^ey placements are of unknown but mrcTereate; "^ ^'"'^ ^"^ ^''^'^ ^is- outcrops of the Bruce series seem To £ a ' n T ^""""^T' '^^' """^ern the eroded surface of the Z-HurorlJ, a "^''^'"^^ ""^^''^'^^^ "Po" rocks have been much diZrb^r TsTr^r'T' ^" ^''^ ""-"^n ■ntense shear zones between th^ m.ll P"*"' ^''^^ ^^^ vertical; great amount of .ntra-fTmatiotl mo^^^^^^^^^ ^^^ify to the addition to the great displacement of the ii. ^'' '"''''" P'^« '" most of Timiskaming reg.on. the Brut a„d cXt"'-^- /"-"«"-» 30 degrees, but in the Espanola area thVrH^. T'""' '^'P '^^ ^han than 30 degrees, and for Vhe most Irt J^ ""^T'^y everywhere more dp is prevaihngly southward VCl^r" '^^ ^^^^ degrees. The thrust was not normal to the strike of th/f T"^, '"^"^^^'ons that the of sheared conglomerate is^arSar^J^^^^^^^^ f '^"•'^- "^"^^ ^-^-ony was great lateral displaceme^. Tt no evtr '" r^'"^ '^^' ^^ere the extent of this movemen Th" '^t K """^ ^°""^ ^'"'^'' ^^ows show the effect of great thrust forces ^ '^^" metamorphism. -k^tr^s;:^^-;^^:^;^:^^^^^^ and partly stratified days butch iLrrf'*' "^'P^''*^' »«"'dery till, flats. The stratified cl^s a„d tnds L ""'t ^■''^'' ^^^^ ^^^--Ve northern half of the area ' Particularly extensive in the Table of Formations. In the following table the fr.r.„o»- the youngest above format.ons are arranged in order of age. Quaternary Post-Glacial ?,.-.• ^'-«' fePa^d aeTcit^' '"' '^'"^ *^''«- Huronian '^'■"" "'^""formity Keweenawan Or^ • j- Cobalt series '^"'^^coZc^ ''■^^'"'Phism. and diabase injections. Gowganda formation. Massive "Slate" ^„ i member ^n^lomerate Greywacke and slate! 1^ ^*- Bedded conglomerate. . . . ! .' . ; .' .' t^ Bruce icrict Pre-Huronian Unconformity Serpent quartiite 8,000? Espanola eroup tspanola limestone 2f Espanola greywacke 280 Bruce H'liextone 150 Bruce n glomerate 400 Slight unconformity Miwisiagi quartzite 4,000 Gnat unconformity OroKenic Hiastrophiam and granite intrusion*. Igneous conliKi Basic ill I usions. Igneous contact Schistified seclimcnts. The correlation of these formations, and their particular nomen- clature are not casrusscd hire; they are being treated in the work of larger scope by Collins. Any intention to correlate the rocks north of lake Huron with the well known formations south and west of lake Superior is disclaimed. The use of tht name Huronian in this repf>rt should not be interpreted as equivalent in meaning to either upper, middle, or lower Huronian as used by geologists of the United States, nor is the term pre-Huronian intended to mean rocks old^r than all of the commonly called Huronian formations found south and west of lake Superior. It may be well to emphasize the diflference among the unconformities above noted. The unconformity which follows the Keweenawan and which preceded most of the Cambrian period is unquestionably of the "revolutionary" or era-ending type. It is found around the world, in almost all places in which both the Proterozoic and Cambrian formations occur; it is practically universal. The pre-Huronian-Bruce' unconformity is no less notable. It succeeds profuse vulcanism, and intense dias- trophism, and it represents a long period of very advanced crosior. The unconformity between the Bruce and the Cobalt series is more of the character of a profound inter-periodic unconformity. The other unconformities mentioiied are considered to be of the order of inter- formational breaks, and of slight significance. 1 It is thought convenient to denote the unconformity following tlw pre-Huronian and underlying the Bruce series, as the pre-Huronian-Bruce unconformity. Similarly the peneplain which was developed after the Keweenawan injections, and which was older than the Camhrian formations, will be called the Keweenawan-Cambriaii peneplain. This is an expansion of the German usage of coupling the names of glacial epochs In order to specify the interKlacial epoch, such as the "GUnz-Mindel-Interglacial-Zeit." Pencic, A., and Brilckner, E.; Die Alpen im Eisteitalter. vol. I (1909), p. III. f^^ - Unoonformify Uhoonlbrmiryf r Brvc9iprias{ I I ^"^'W^W^J" "**'. QWBl. Figure 2. Diagrammatic sections of formations in Espanola area. CHAPTER III. PHYSIOGRAPHY. The Espanola area shows a local phase if the physiography of northeastern Ontario. In considering the histi y c' any area one must take into account the evidence provided by il^ environs, and for that reason much of the following discussion must relate to the larger physio- graphic unit of which the Espanola area is a small >art. Before ihc depositi^^n of the Bruce scries, it is certain that the underlying pre-Huronian slates, schist., and greenstones were intensely metamorphosed and very deeply erodec The nature of the pre-Bruce surface cannot be determined in the Espanola a'ea but we know from the relations elsewhere in the coun i •- well weathered land surface of h deposited, the pre-Huronian sedii the land surface reduced to a pen( Between the deposition of thi apparently was not subjected ' Huronian-Bruce peneplanation ; to remove the overlying formatkrii Bruce limestone.' The approxini Huronian series shows that tht; deposition of the upp)er, was ul tre noi after the deposition of the Cob.ilt sK-rios were intruded by diabase sills dmi dykt-. Before many of the intrusions, bt jt after soi greatly elevated by thrust fault! », md i^ U' Before Potsdam time thisi i. vatedsu to a peneplain. In northt^' >ntari described the peculiarly even skyline (PI its existence, but there has been little agreement a origin. It seems certain that there was a period I' '\h of lake Huron that it was a Bv'fore tr e Bruce series was «rie,* hae i,. - n truncated and md rlje CM>. series, the ar^a iih er ion as* luring the pre- advai rvii en< tgh, however, 1 other kKalitii- down to the quiifity 4 ;'>k]iBg in these two lergerK ui the lower, before the c type. Sirne time meuiar)' i .rmations iW? of Keween^iwan age. I ihti^in. the district was m «-ni- ' have been reduced 5ibwi was the site of also in the Onondagan I kist' me period the re- the Palaeozoic sediments that time, however, is i is known of adjoining lA) rimiskaming region has . Ni) ne has questioned r the time of its f early Palxozoic > Colliiu, W. H., G«ol. Surv., Can., Mui. Bull. No. 8, 1914 pp. 24-25. 10 dep9dtion. which hsted into the Nlngarw epoch of the Siluriu period • ' ^t^ ™!w "?" *^* *^ penepl.„.tion i. po,t.SiIu^. ft^ other h«,d. eldmaii' report, that the clear-cut peneplain of the ft.- ^^":^ o '°"*'u »^ Gi*at Ldce. U buried unde?the .urrSTnd^ ^^^«1 '^^^ "* •"«"*' • ^^"~' ™"** ^id*' diatributioHf thePotKlam ,h« nowexiau. ud a very widepre-Pofdam peneplanatiorf the ^pla.„ which » over the whole lake Superior region, perhao. .^Sa^oJTVr'".'^'""''""'- M. E. WiL. beliLa'tr/t S ^iw J u ^Ti""""* "«*°" P"^""* to Silurian deposition wa. Sdurmn Und area; he continues that the evidence there doe. not sh^ e^ iSn ^K ?T' '■'^°" •"" "^^ •*'^" ""^" ^he «a .ince the Pal«orS^ sSitSL . 2.K ^'^r*^* "^ P'^'*"*' ^''"P* "^ P'e»tocene. a^e Sl^ R Schuchert» state, that Onondagan corals spread i^to the Hud.on Bay region as well a. to the south; and in his mapTccom^n J„g the ^cle quoted he indicate, a «.a connexion between soutJ^SJ SI lir? ^^ f ""' '^' Ithaca-Chemung epoch. He does not^^y atest time at which the T.miskaming region was under the sea. Thu. ^g.on ha. been one of subacid statu. «nce a. late a. the OnondagllJ l.»«„^''!i"*?*'l* °' *'°"°" ""'* **•*" ^^ ^« thought by some to have ended w.th the uplift of the so^alled Cretaceous peneplain S E Wilson* po.nu out that we have no evidence that the Creteaous pene: pUjn ever extended over this area. Ten years before. A. W. a wK had said that .n the extreme northwest of Canada the strata cassld« Creuceou, are found resting on a peneplained surface, and that^N^ b^S;'S:e """r- '•''*"*"' ^^^ ^^"•^" "--^'^tones are foun^ torfer,r.g the general region, which suggests that it was above sea- level and subject to erosion during at least part of the vonian ^rSd In regard to the peneplained surfaces in WisSnsir and Michigan w[l^„ quoted the work of Van Hise. but Van Hise.» himself. ^>^ S ti,e Ws" • Weldman, &. op. cit.. p. Ji J. •52!^. "m." ^- *^- "*^ "'• •'"• «>• "■ •Schud.^. Ota* Bull. G«l. Soc. An... «1. XX. 1908. p. 540 Md noU No 77 ',Z^' ^: ^:' '^'- ®''"'- ^'"- "«■»• »■ «9". p. ". • WU»n AU«d W. r... Jour. G«L, vo!. XI, mj. p 658. - Vw. Hi«, Ch.*. Science. New Ser.. VOL IV (IM«). p. 59. ll ooiuin and Mir' '^n regions, that in calling the age of the Witconain peneplain Cretaceooa, it is no more than conjecture; and writing of the Michigan plain, he saya it is about 10. feet higher than the Wisconsin plain, about 150 miles away, and that they are both probaUy part of the same, much more extensive plain, and probably Cretaceous in age.' Several years later, R. D. Salisbury* added, "There is some reason for thinking that the important topographic features of the central Missis* si|^i basin are chiefly of late Tertiary or post-Tertiary origin, developed from a late Tertiary pcmplain now represented by the summits of the higher hills and uplands of the region. . . .It is true that these summiti have sometimes been interpreted as remnants of a Cretaceous peneplain; but the conclusion is not firmly established, and the alternative suggestion is entitled to consideration." There is no need of going further afield to show that the age of the supposed, very widespread peneplain is not determined. However, it seems safe to say that the Canadian shield had been reduced to very low relief before Silurian times, and that the Onondagan limestones as well as much of the Silurian sediments were deposited across the present divide between Hudson bay and the Great Lakes. The drainage, consequent to the uplift of this area of deposition, has removed entirely the Devonian limestones, and all except scattered patches of the Silurian deposits, and has modified but slightly the underlying crystalline rocks which were already of only low relief. Although the superposed drainage cut across hard and soft rocks without selection, and perhaps caused the topography of that time to be marked by cliffs, gorges, and rock bound canyons, and by a definite horizon to which the hills attained, yet, long periods of erosion must have removed such rugged features before Pleistocene times, and another origin is to be suggested for the relatively youthful system of drai.iage which was almost entirely disorganized by interglacial processes and by the glacial deposits. It is possible that the country was uplifted and eroded after Devonian submergence, reduced to the suggested base level by the beginning of Tertiary times, and uplifted again in a late Tertiary epoch. Subsequent to this uplift, erosion proceeded perhaps to early maturity before the Glacial period commenced. Thus the present major relief may have been made entirely since late Tertiary times. Although means of dating the physiographic events in Timiskamingre- gion between Pre-Cambrian and Pleistocene times are scanty, it seems certain that there must have been a period of base level in late Palaeozoic times, so that it is likely that a topography in old age was rejuvenated by a Tertiary uplift, and that by Pleistocene times it had been changed to > Op. dt., pp. 219-220. The italici are the author'!. < SalUiury, R. D. "OuUinet of geologic hit. ~ry," Wlllia and Saliabury, 1910, p. 266. 12 one of early maturity. Maturity is suggested, for in Timiskamin^ repon some divides are well ma, Iced and unbroken in places fo Sf (Sd upl'ft, as the even (rests of the quartzite ridges and the flat tops of the eier^ iTZ' *"*'^'\" '°™^' ''''' °^ '^' ^^-"^^ --'- How! ever, .t is not supposed that evidence for determining the ages at which these processes had become marked is to be found within the centS L^ir::p;rt'bur?t°' '" ^'"^z:^ ^r ^^^^ ^•^^^-"y --^^-^ bldeddTbv th! / " recognized that the physiographic history must De decided by the tracing of peneplains and other units of physioeraohv into the formations of known age which border the pro^nce Fmher Jt IS suggested that all land surfaces in the TimiskaJing re^n Ice the Keweenawan-Cambrian peneplain' have had an accordance of summit ^vels by ;-.nheritance ". The pre^nt accordance of summit levermay be the direc descendant of the great Pre-Cambrian peneplain wS unquestionably characterized the present land area. ORIGIN OF CLIFFS AND CANYONS. m.J^'f T'^^l'^ ^""u- ?^ ^'^^^"^ •'•"^ ^'^ '^^"d^dly steep sided and many of them have high cliffs, although they have Lcn subjected to much giac^tion. Many of the hills have quartzite lower slopis with a diabase ridge or backbone; the quartzite has been shelter^ on the IfThis n"h " '"■' )' ^'•^ "''" "^'^^^"^ ^-b-- A striking example m Merritrr'T "/^""^ ■" ^'^^ "-^heastem part of Espanola area esiJJan tl hT? ''• f*^ '• '"^'' "'"«^"'°" ^^- diabase is more thl,!T '" °^ ''°"°" ^'•'"^'^ '^^^^ ^''"^ «t ^'O'k in that region than the quartzite, in spite of the fact that it weathers now more rSy than the much less soluble quartzite. At first thought, it may seem unreasonabe to admit that the diabase cliffs rise above the quartzlt^ by reason of the toughness of diabase in resisting glacial abrasion ThcTea! ice action. Such, indeed, are the properties of the rocks; but, in some places, the space between the top of the diabase and the top of tTe scores of feet and this seems a large amount to attribute to selective cuSnT' """"T'Tu^ "^"^ ^''"^^ P°'"^ ^° ^ --" "^ oSZ cuttmg generally, although grooving, roch^s moutonn^es, and othe relatively minor traces of glaciation, are abundant, and ome o" the tte enT^f rT"""'-'" !" •^''"^ "^^^^"^ '''^^ °^ development before the end of the Wisconsin glaciation, for there is little talus at the base of many of them. Nevertheless, if the origin of every cliff Jas due to ' S»e footnote No. 1, p. 7. •Daly. R. A., Jour. G«ol.. vol. XIII, 1905. p. 108. 13 selective processes during glacial and interglacial epochs, and the writer is of opinion that most of the cliffs of this region were so developed, then, in order to make so much difference between the amount of quartzite and the amount of diabase that was removed by cliff action and abrasion, there is required a great total of erosion. Cliff recession requires enormous transportation service to maintain its continuation, and the Pleistocene ice-sheets are thought to have supplied that transportation. Many cliff faces are the loci of contact metamorphism. In many places, where contact between diabase and quartzite is close to a steep slope, the shattered quartzite has broken away and fallen from the face of the diabase mass, thereby forming a pile of quartzite block talus at the foot of a diabase cliff. Examples of the influence of the contact zones upon the topography are not uncommon. North of Thessalon, especially in Rose and Bridgland townships, the diabase cliffs are promin- ent. South of the lake in section 28, Rose township, there is a high hill due to the protrusion of a diabase dyke, as a core, through the quartzite formation. Between the diabase and the quartzite there is a gap 2 to 3 inches wide. The quartzite is very much fractured near the plane of contact, and the diabase rises with cliffs above the quartzite, forming the ridge of the hill. Also in section 19, Rose township, there is a prominent hill of the same character, in which the diabase core rises 20 to 30 feet high above the top of the quartzite, as a long, narrow, even crested ridge. In Espanola area there are similar hills, some of which are indicated on the diagrammatic cross-section on the accompanying geological map. In lot 10, concession IV, Merritt township, the diabase and quartzite hill which rises from the sand-plain has developed a cliff on the south side, evidently by the falling away of the quartzite from the diabase contact. These examples prove that, under conditions which have affected this region, diabase is a more resistant rock than quartzite, and that cliffs tend to form at the shattered contact of quartzite and dia- base. This process does not explain all the cliffs, nor does it explain the canyons in the massive diabase. Furthermore, there are some cliffs of quartzite, although they are not so common as the diabase cliffs. On the border land between Rose and Bridgland townships, and parti- cularly near the corner of these two townships and Haughton and Galbraith, there are many diabase intrusions, which typically are bounded by cliffs. In lot 12, concession VI, Bridgland township, a deep canyon runs east and west through one of these diabase masses. The south rim of the canyon seems to have been rounded by ice scour, and the north side is extremely precipitous. One-fourth mile northeast of this canyon, the diabase mass faces east over a widespreading swamp land in a precipice as high as 300 feet. This cliff is broken by a hanging valley 14 blocks of all sizes ^to io 4? 1^1™'^""! ""''^ "P ^^ diabase through the valley k very smS IchT ' ''n * *''" ''*™^™ *'"<^h ™"» blocks which Jp^Z r alS rne"^ ' *° ''^ '^^"'^ *'»« ''"«« diabase masses are bordered bvS J^ •'" ""^^ <=^s ^^e larger the diabase rises high aW S^etS;'"^'! "' ~"**" ^'^^^ ^^^^^^e Steep-sided. V-sha,S v^iryst,dTffs ,t "^ '"^"^ ««J'mentary rock, region. ^ *"'' <^''»« characterize the diabase of the and largely of int^erglaa^ deSlotS^n? ^^ ^'''^■^'^"^'" '" «««^' there were four epochs of gladrtST^^^^ ^^^^ " '^ remembered that has been eroded^ "^^rleH/,^^^^^ especially is this so b^3of t^^l,^'"^ ^."^ '«^ remarkable; and carry away accumS^ d bris S^LV "f ' ^"^"^^^ P'"-*^ <>« processes, particularly in the Ssl of rockT.t^',^! ""^^ ^°' weathering metamorphism. Co 'tact shaSinl r^.SUr^f' ^ ^^* increase the scope and effectivenp « ^r T .^"^^"^portation greatly glacial weathering XrnaSrtr.^r'?'y'"^- ^^^' °' i"*^^- debris can accoun't fo^TS tlul of':^osion '''"'' ^-P^^^tion of P^ana^t^r tI'^Z^TZZ " Zl"^^ ^^-^ T""* °^ ^'^'^^ abrasion of ice scour had been iZfZ "^ P°'"*^^ °"* ^^^^ the of lake Timiskaming the deSL'ir^^^^^^^ movement. He was^ferring'sS" H^to"!? "^ -'""'k"*"^ *° '- ice scour had made lake TimUtIZ" ., ^* °P""°" ^^^^ unaided the valley is of PrlpatJz^roS'r^^ '^ '^ '"-^ that abrasion. Wilson' savTt^l ^^ ' ^"''""^h deepened locally by ice from the PoZTa:;a.Tp^'ri^ td'^hS" f ^^"^^ ^' '^"^°- ^^" post-Glacial, but that m^st of'thl ^^ese gorges are. in some cases, cedent in origin to sSrctull 1^ ^'' Pre-Glacial. and perhaps ante- Evidently, he places the bu^de:^^^^^^^^ - '--'^ly superposed, to the Ice Age. In the re^rt of T T ^"^ T" '^^ *''"" P'«^'°"« there are some statements Sdfi° 111 u'^'"' T^""' °" ^ipigon basin' beer, insignificant as a fact^ J ^ """"f '^^ '^* «'^^'^tion to have nomarke?contrastsinpt^e „^^,'™, ^^i'"" ->'^ '^^' ^"ere are ice-eroded, and those which LlrcoS^JT? ' ''"'^ ^^''^ ^'"^^ ^^" characteristically form steep^td^ diis "^d""' '^''- '"'^" '""'''^ — - ^ P-«agea clitts, and m many instances there •^- A^ w: ^i^!:^r^t^, ^- «■• x^. '. mr. p. «. • WU«on. A W C rw-,1 a ^T ' '""• «""■ ««0.««2. • It i. to'^- n^-tSr^"'if^- >s»- '• "•"• "• •"• IS are piles of talus at the bases of them, but only in a few cases does talus Feadi to the top. From some cliffs which are glacially scarred, the talus is removed entirely, but at others, the talus remains partly buried under the sand-plains. Some of the talus piles are truncated near their bases by the ice action, but in some places in the lee of diabase cliffs the talus piles remain apparently unchanged, which shows that there was very little ice at such places. Nevertheless, for the most part, all the talus piles then extant were removed by the last gladation. Wilso'i was not unmindful of the influence and duration of the intergladai processes, for he specifically assigns the cutting of at least one canyon to an inter- glacial date.' But it seems to the writer that he did not consider inter- glacial processes quite enough. The fact that the last gladation left, a few sheltered talus slopes unstripped, is not a strong argument that nearly all of the talus was not carried away both in that epoch and in the preceding glacial invasions. The transportation of talus from the bedrock, and from the partly covered cliff faces must have been nearly complete in each ice advance. The effidency of cliff cutting is very great during alternating .»n- ditions of rapid, frost weathering action, and powerful transportation of debris. Efficient erosion is largely a matter of removal of the de'^ched waste at the earliest possible moment after its separation from the bed- rock. As regards erosion, the chief service of the gladal invasions was to carry away loose material that had been broken down already by weath- ering. W. D. Johnson* pointed out very cle£U-ly the difference between cliff sapping by gladal action, and abrasion by a moving glader or ice- sheet. Abrasion is great when a glader is moderately loaded with hard and angular drift and confined in a restricted channel, yet when the glader is spread out as a sheet over a surface of slight relief, its corrasion is relatively insignificant. But even if its scouring effect is small, its transportation power, and its ability to pick up and pluck out masses of loosened rock are practically unimpaired. It is the contention in this paper that although glacial abrasion may have been relatively small in the Timiskaming region, other erosion by ice and frost action must have been very large. Although referring to mountain glaciation, Johnson' urged, 'The upright element in the profiles, it would seem must be reg?rded as a sapping effect in which scour plajrs no part at all." In sappinf processes frost work is active, it requires a suffidpncy of precipitauon, and temperature changes oUch that there is t. most frequent possible change from melting to freezing, both of which con- ditions may be altogether independent of glaciers. « Wlhon, A. W. G.. op. ch., p. 126. » Jahxmm, W. D., Jour. GvA., vol. XII, 1904, p. 57J. • Op. dU p. ilS. J 16 However, the time preceding the advance of an ice-sheet, and the period following the close of glaciation provide favourable conditions uu^ *''*'°"' ^°' "'"siderable cliff sapping will be effected by the sheltered remnants of a retreating ice-sheet, and by the seasonal accumu- lations of n4v6 at cliff bases during the rigorous climates which, in moder- ately high latitudes, probably precede a glacial advance. If former periods following ice retreat were times of cliff recession, then at present there should exist examples of such action, and examples abound. A though there are some diabase cliffs which still bear Rl.tcial scare upon their fronts, thereby proving that there has been no retreat of the chff since the withdrawal of the glacier, there are many talus piles which are surely post-Glacial in origin. This is explained by the fact that recession of cliffs is largely selective. Cliff recession is produced by such agenaes or conditions as frost, jointing, contact metamorphism. or other natural weakness aided by an agent of transportation at the base, such as a large stream, a glacier, or a lake; and cliff recession is hindered by natural strength of the rock, and by a protective mantle of talus. Some cliffs which border sheltered shores are now in process of ' JT'u? f " accumulating at the bases of the cliffs more rapidly than the feeble shore processes are able to remove it. Manyacliff isreceding at one place and becoming covered with talus at another, depending upon its position with respect to a shore-line. Moon lake, 15 imles north of Blind River, discharges into Tendinenda lake through a narrow bay, and on the north side of this bay there is a Hiff formed of a diabase sill intrudingquart- "var T''^''^^'"^"^ ^t the east end of the cliff is receding, but the main cliff facing southward and bordering the narrow bay, in which wave action Ipi"?' ,3T-' .'f ''^^ ''°^^'^'^ ""'^^ ^^^ P"'"K "P ^' 'ts own talus (Plate IB) Similar decadent cliffs border other lakes, such as parts of the Palisades of Tendinenda lake; but cliffs which form shore-lines exposed to vigorous wave action and ice shove are being cut back rapidly by sapping action. There must be thousands of such shore cliffs in the Worth Shore region, and their total annual recession is enormous. Many cliffs away from lakes are breaking down rapidly. Quartzite cliffs seem very susceptible to gradual destruction. Near the north shore of Loon lake, lot 1, concession II, Merritt township, there is a great hill whose south side is completely covered with a steep fan of broken quartzite blocks. The blocks are rather cubic in their habit of fracture and are, for the most part, aboitt 6 inches in diameter. This is surely a talus pile which has grown so high that it has covered the original quartzite cliff face, and thereby stopped the recession of the cliff. Although this IS perhaps a case of exceptionally rapid cliff retreat, it Illustrates the activity of cliff recession since Wisconsin glaciation 17 If, previous to an ice advance, the cliffs had accumulated great talus piles, then a condition of pseudo-equilibrium would exist, and the speed of weathering would be greatly decreased. Removal of the talus by an advancing ice-sheet would reinstate the cliff, after ice retreat, in a condition favourable for active recession. On the other hand, the ice invasion might cover the cliff faces, and bury the country with glacial drift; then superposed streams might be located across some former cliflfs, and canyons would result from the recession of the consequent falls. A comparable case is mentioned by A. P. Low;' Bowdoin (McLean) canyon has developed below Grand falls on Hamilton river by head- ward cutting. Still another means of interglacial erosion is the rather uncommon process of chrystocrene transportation, which has been described by J. B. Tyrrell.' Springs at the foot of a steep slope, by their alternate freezing and thawing, and by the assistance of gravity, move talus in large quantity and in massive pieces a considerable distance. This is mentioned here because such a process seems competent to have formed the great scree cone at the mouth of the hanging valley mentioned before.' Although this is not a spring, but a stream, and, therefore, not strictly speaking a chrystocrene, nevertheless its agency is essentially the same. As a stream, its velocity and volume both are too small to enable it to carry along large blocksof talus and to discharge them over t ? dump pile. But when it freezes, every boulder, large and small, is su: 'j jct to the ice shove; so, aided by the steep slope, the small stream, little by little, moves a surprisingly great amount of waste. Wilson,* quotes Low as authority for saying that in Labrador there has been cutting of post-Glacial canyons by still another process. Glacial deposits have dammed the old gorges, and rivers have cut new canyons in the bedrock, since the last glaciation. Although Labrador may seem rather far removed from the subject of this discussion with reference to the post-Wisconsin epoch, it is not at all impr^' ible that similar con- ditions attained even greater development in the Timiskaming region during some of the much longer Aftonian, Kansan-Illinoian, Illinoian- Wisconsin, interglacial epochs. Although ice scour may have been relatively slight, the nher low temperature processes must have been very effective during glacial and ' Ix)w, A. P., G«l. Surv., Can., Ann. Rept.. vol. VIII. pt. L. 1895, p. 301. •Tyrrell, J. B., "Rock gUidera" or "Chrystocrene*." Jour. Geol.. vol. XVIII (1910), pp. SS2-SS3. • See p. J3. The wriwr U especially Indebted to Mr. F. B. Plummer for first-hand information on •bnilar phenomena in the White mountains. Huntington ravine, about one-half mUe east of Mt. Washing- ton In the Presidential range of New Hampshire, affords a striking example of the movement of great quantities of large sixed scree away from a fracture tone. In this case there is not even a small stream, nor U there watershea enough to provide more than an intermittent aiing of the spaces within the scree pile with water; yet the movement has been considerable. • WUson. A. W. G.. Jour. Geol., vol. XI (1903) , p. 660. i ■a IS IwU", down lato block trfuTw.^J^f "^^"1 "Meptibk. to S^' T^ S '»" ^ "M^intL^"'^ tat'- 'K recent work in Iow«rti«U have mnliniMrf TV, r^ i_. . Jdd to th. n«n.b« of both lnt«,S^'::fSS^t2^ rriSf^Jt?" '"^ "P**. th« „ „„, far Wo™«lon upon UU. point which «,on,S^^«^ch .SL^ 19 CHAPTER IV. STRATIGRAPHY. Pre-Huronian. SEDIMENTS. Distribution. The oldest rocks exposed in Espanola area are metamorphosed sediments. They appear in the northern part of the district along the Canadian Pacific railway, northwest of Espanola Mills, and in the north- west half of Hallam township. Stratigraphic Relations. The pre-Huronian gneissic granite, which intrudes these sediments and thereby serves, in most places, to mark the distinction between the Huronian and pre-Huronian sedimentary formations, is exposed only in the northwest corner of the area, where its relations to the old sedi- mentary rocks are obscured by faults and the overlapping lake sands. Although the evidence of difference is not clearly shown, the greater age of these pre-Huronian sediments is indicated by their very great meta- morphism as compared with less alteration of the Huronian rocks which lie on them in the northern part of the area, and which in the south make up the greater part of the solid rock outputs of the region. The age relations are not indicated by the contact between the two series, for all the contacts observed are faulted ones. The difference in age is suggested by the unlike lithologic character of the fornjations. The pre-Huronian sediments are greywacke, and quartzite, and especially the metamor- phosed equivalents of these rocks, chloritic, micaceous, and staurolitic and sericitic, quartzite schists, also hornblendic, and garnetiferous schists. The Huronian sediments are arkose, quartzite, conglomerate, limestone, and greywacke. In most places, the dip and strike of the Huronian rocks are easily determinable, but almost everywhere in the region, it is diffi- cult to distinguish the bedding of the pre-Huronian sediments from their schistosity. Character. On the map accompanying this report the pre-Huronian formations older than the granite-gneiss are shown as divided into two divisions, the sedimentary and the igneous rocks. Most of the rocks are now extremely schistose, but many of them show their sedimentary character in spite of their metamorphism, and in a few places where they have escaped pro- 20 s rf:r;t^':s.st Lrr^ ^r-*-- ^'''— phyUite. micaceous ih" IT^U^ k:"S;'^S'' T^^-'ateor quartzitic schist. greywacke schist, staurolitic schist, and ^y colour onZ^nc:t^^^t^ anTi^'l i^ ^V ''"^^'^ hammer bloi^r^ Sv 1.' "T"' ^°<^k which shows the marks of a exposing a glcamS^g'm^Lus sS" iTth ' ''""' ""^i!^"^'^ P'^""' the rock is plainly ban^ST In nT; . *''^.«''P°«"'e below the dam. one-half inch thicknesHnH «.! T, ?^''' " '''°^* ^^nds of about is about the attt^rpaS,! ;t"t^ ''f!,* ^^'''^ P^^ foot of dark rock and more coarseVTarerit fho^VtkStir'f « '"'' "T '^"^'^ many small faults of about 10 feet XoJ^ Th ' «^rumpling and of only one foot throw and less Thw' ^^^^ ^'^ '"^"y other faults metamorphosed soTve«t that ^in" ■°" ^"' ^'" '^'^'^ «"d geneous material, it hri^oM "e-lii: '^r'^'"' '"* ''^'^^°- parts. *^ eye-like borders around stronger Micaceous Schist, or Greywacke Schist tk;» i • the phyllite. but it seems to STore quartidc O^;^ '' 7"^ f" ''"'' *° was originally a fine-grained JnZ^r^Z Tu\. ^ '"'^''' '"^^' *hat it morphosed. but theTeaJl^^jll 7^''' ^^ '^^" '"^^"^'y -"eta- typical schist. False^LavSr S'^h T'u' 'l^^ '""^"^^ '* *° ^ schists, and sericitization hi'^on'T o sucVL^^^^ usually found in and tends to crush rather thL iv j 5 ^''^^ ^''^ ™«^'' '« weak fracture faces hsho^fthe sW^^ orc^l' ."""" "°"^- ^'"" '^ of the schist is the de^SopmeTof l'^ L """"• ^ f^""arity oriented with planes SeUkher toT.'' "°"*''''' "^^''^ ^'^ "«* They are distributed aToH n S'-g^LVvTh " *2 *'' ^^^ ^'^^^^^^• rock, and cut right across ^mJ^!u u- .^''"0"Khout the mass of the that the^ pheSTc^si 3T0 4 m ' "f''°'''^ P'""^^" ^* '« -^"-'"ded the very fin' -graiS tr L^e whTh hL rdHhe"' t' 'T °"'^" ''^'^ of Webbwoirtrthe/eisastrdlLT^^^ Twenty chains eas't gradation through micaceous schttTto^h^^K^^^ ^^^^'' *° P^^^ by forms the hills^ort^o^WebbwC tetr '""''''""'"' "'"' vveoDwood (see following paragraph). In 21 3 the southeast corner of Shakespeare township, the staurolite schist is well exposed. It is clearly a highly metamorphosed phase of the grey- wacke schist. In some places it looks much like an intrusive rock, and conforms closely to the description given by Coleman' of staurolite schist in the neighbourhood of Sudbury. In some places bedding lines have been preserved in spite of the great anamorphism and development of large (2 to 3 inches long) crystals of staurolite. Under the microscope, quartz grains 1 mm. in diameter are seen to make up the basis of the rock, but many secondary minerals have been developed around the quartz grains. Secondary mica and amphibole are abundant, and there is some albite; but large crystals of staurolite nany of which are in cruciform twins, make up a prominent part of the rock. Quarltitic Schist. This rock is quite different from the mica schists and slates. In colour it is greenish grey, and it is much sheared appar- ently parallel to the bedding. Although the rock is evidently quartzitic, it is marked by an abundant development of mica which is green on fresh surfaces and reddish brown on bedding planes. Because this schist has sheared into lamina of the order of 40 to 50 ptr inch in thickness, it is a very weak rock; pieces one-tenth of an inch thick can be broken easily in the fingers. In some places it has a rather indefinite slaty cleavage, and in other parts it is more like ordinary quartzite. It looks fairly massive on weathered surfaces, but even in parts that are not schistose, freshly broken pieces reveal an abundant development of sericite. In the south part of Shakespeare township and in concession VI of Hallam township, there are high bare ridges of pre-Huronian quartzitic schist. The schist is highly quartzitic, and weathers with a gleaming white outcrop. Under the microscope it is seen to be almost pure quartz, with a considerable development of sericite. The quartz grains no longer have the equi-dimensional shapes common to con- stituents of clastic rocks, but they have irregular, crenulated margins, and the grains interlock. Many of the quartz grains show marked strained extinction, and elongated grains are arranged distinctly with the long axes parallel. There is no sign of the outlines or shapes of the original grains, but it is plain that the grains have had great secondary growth. BASIC INTRUSIONS. Into these sedimentary rocks there were intruded some rocks of basic nature. They are now metamorphosed beyond the possibility of determining their original composition, showing a marked develop- ment of chlorite and hornblende. A quarter of a mile directly north of Espanola station on the Canadian Pacific railway, there is a mass of 1 Colenum, A. P., Ont. Bureau of f .», Ann. Rept. vol. XIV, p^ III. 1905, p. 8. 22 J'r.TO'n"^^^^^^ •«• o' • -" hn.. and o„ •ch»t. The wuth side of the Si ^^ **'. •"•^^'Pho.ed quartiitic and the bare face of the «^k k TV." " •"* '^'^ '«"» theZSTt which weather into little iJTnl ^ '*J*' "P**^'''«' ^^ Pink wrnel of "-'^ hornblende wS'nS'nSble'Z!'"- /"^^ -"^ »^^?; bH.t.te. No feW.par i, reco^Sr bu.T""* °' ""^^ «"d bTck "y»t» of garnet a. large aTX!!. !' , "* .^^f" "* numerous phenol the ma... Thi. i. th^gh" ^^"2^ H.'"'' '" *'*'»«*' »''~S« development younger thSn the g^L'SL^T^ ~"^« metamorphl «m/Iar mineral a«odation.a«nJ^foL^?n^^ °' *''"* »'•"«■ ^^ •edments of the district. On the .^T* k f*''*"^"*' '"^amorpho^d •tone Which intrudes prelHu^nia^ sclfi^Tn^t' ^'!'^'^^>"-''e • a^g„^ Th.8 suggests that the greenstone at F^I •*""" '"^"^"^ ^y granite which is found cutting CprlTumn^r!!^ " " °"" *''^ ^^e ^a,^£ correspond to that whL L W S^A^r"*"' f "' ^''•'^'' -^"« o VI. Merritt township, there is an in^on^^' • '" '°* ^^' ~"««'on thought to be pre-Huronian. iT iitSX !^' '*""°'" "^^ ^^ich i. and he contact zone is very much nSfmo^h^r'^''"^ ^''n«nt». the .nterior of the mass is le« ^^7^^ ^^^"''^^''y- although fnargma zone around the massif tn^tfT"^-' "^^^ » « <^'nk^ « gneissic. Under the microscL^fcl . . '""°''' '" '^'"''^h the rock to be. 50 per cent homble^^th'! t^."*'^' "«"-■•«'« are discove^* clastic quartz and feldspar. ThTre ar. I^^T^ °^ granulated, cata- S' r^ ""."ch altered^Tlarg^ :^^^ '- fresh-looking plagioelase euhedral apatite crystals, some of^S «rA ^^^ '"'"'^'"^'^ «« 'arge magnetite, and titanite. The text^t • "\^'°^^"- ^ome biotite flakeV stals are hypidiomorphic ginulaMnduH'^-'*°*' *^^ ''o^'-blende a?.' penetrated by them, all roS o^wJ?'"^ T.^'.^' ?-^^ l^origin. --ne.t.5::Sfrth^:^resTXt^^^^^^^^^^^ • cln.'; w: S: S"dfrp-;f "■• "-•• »'^- '^- «■ -"*■ pp- -". •Sm pue 20. the pre-Huronian and the Bruce aerie* are presented, and the conclution it stated that the Huronian roclu have been thrust over upon the pre- Huronian terrane. It is certain that the Bruce series is younger than the rocks which have been called variously, Sudburian, Timiskamian, and here pre-Huronian, although Lawson' states that the Bruce series is probably ok!er than the Sudburian series. BRUCE SERIES. MISSISSAGI QUAKTZITE. Distribution. As shown in the geok>gical table on page 7, the base of the Huronian rocks consists of the Mississagi quartzite.' In the Espanola area there are ratiier extensive outcrops r>f quartzite and conglomerate which are thought to be correlated correctly with the Mississagi quartzite. They lie in three bands, two partly across the area, and the other one from the southwest corner to the northeast part. The largest band is not a continuous outcrop; the conglomerate and quartzite appear in detached hills which stand up above the sand-plain. The hills resemble islands rising from a lake, and s"ch they were in Pleistocene time. The northerly outcrop of Mississagi quartzite is bordered on the north edge by a conglomeratic phase, and it seems to have been thrust against and upon the pre-Huronian formations. In the southern part of Merritt township, there is another outcrop of the same kind of rock, but the conglomeratic phase is absent from the surface. This outcrop has fault contac*' i ti " northern side, and is bounded on the south side by the forma overlies it stratigraphically, the Bruce conglomerate. The t. rn^ this outcrop into contact with another Mississagi quartzil Hailam township, and eastward it pinches out about halfway > •.>' Foster township. The third outcrop stretches across the southea:.: ■ part of Foster township, where it has been exposed by another thrust fault, and brought into contact on the northwest side with the Serpent quartzite and with the Espanola greywacke. (The Serpent quartzite is the youngest member of the Bruce series, and the Espanola formations lie immediately below it; see the geological table, page 7, and descrip- tions of these formations, pages 36 and 38.) Character. In the northern outcrop, the conglomeratic phase is distinct. A good exposure' lies about 20 chains west of the Alfjoma Eastern railway along the trunk road near Espanola, and there is another, equally good, > Lawnn. A. C, BuU. Dept. Geol., Univ. of Cal.. vol. 10. No. 1. 1916. p. 14. • CoUint, W. H., op. dt.. pp. 17-19. 26 granite. In diSe^l^^Zt^''''',^''^l-^ Pebbles of quam Sd and fine-grained quarSfr BouE oT"" " ~'"^' «^'*^^"artzite. PebblesofgraniteatthesouthenJof Lhjir^^^^^ ^^^^' t*"-" towards the north. At tlTnonhe^^^^\T'^u^f^^^^^ pebbles to be seen. On fresh surflc.,?h ' '?'"' '^'"^ ^'^ "«* even colour, weathc .u, to a da Lr .tade *'?/'""'t"' ''"' "^"'^' ^^^''^^y way; the ,-an.te i. !-s Sttt th J I ''*^'^^ depression s in the quart.' ifiS^J'^f" *''' ,^."f ^^t^, and there are have bee. .er.ovecJ by w. itherhS t/ ''^."'' ^''^ ^^"'^^ Pebbles behaviour o ,h, .s.,, Led ^Hfl^" u u" '! '*"^'"«'y '^'^^^'-ent from the this report. In thi i. ^riJlSisle ""''"' °" ^^^^ ^^ *° « «' boulders and the bouta st^nro... ^ ^f*""* *''^" '^' P-^nite Probably the bouldersTn th^bL, " In ''°'" *'"''• background, grated at the time of their delS Xrl ''' ^''"^ P"*'^ d'«'"te- other conglomerate are stillT^'Iit ?h!:'" "^^ •'^^' *''°^'" ^he M'ssissagi conglomerate is no readifvlhl, ""T'^'u "^''^ °' ^^e places, calcareous matrbc of the Jounir^' ^"* '^^ ^^^•<^' ^^^ in dissolved markedly. In the m on th. A """^'^ "'^t^ is quite apt to be before, there is a good ex^^re j 5^^^^^ the conglomerate is bioXS L l^'t!!r?' "'"^'°'"^'^*^' ^here fault." The pebbles are small and ^.^f;;'^'^ '" ~""^^°" ^'th the andgrey.ackespe.mens;:r:iren^-rm^^^^^^^^^ grained.TkXLfJrs;2:,' Tif /" ^^^ ^'^^ ^^ ^« — quartzitic. and so mnc^le^^ld t^^^^^^ ^^'"^ *° l*^ highly told apart by megascopicTnT^n In I^in"^""' ^"'"^ ^""°t l^ township, the quartzite is verrfine .raJn J V ' ~""'^'°" ^^^ ^erritt '"dividual grains are distinSaWe Evlr' IT.'^^ '"^'^' ^"t the parting which has been dynTmSllvl.f ^ V° ^ ^''*' ''''^'•^ ''^asericitic of these sheared bands thTeSdauIrrr''^?^- ^^'^^ ^^^^l^ering In other parts of the same outcmn 1T / "'^'^^''' '''' ^^^P'^ '"tted h-ke almost pure silica exceptthaf nr I''' '' ^'^^ "'*^*'°"^' ^"^ looks show. This rutted ty^^STurft SheriL"';'?' '^"^ ^^'^^P^" other quartzite outcrops betw. . n ^h Tf . ^ " ^° ^ "^^" also in the 2. concession VI. On' th^t tV fde'^? he T'. ''' ''" '" '*^^^ ' ^^ quartzite is so much metamorphosed tL/t^J^'.'"""*'""'''^ '""• the ' See pace 24. 27 feldspar, aiid cross-bedded towards the top of the formation. This seems to be true also of the outcrops which border the south bay of Apsey lake. In many places, the quartzite has a distinctly green cast, and in others, the small iron content has oxidized to hematite which gives a pale purple colour to the bedding planes. This characteristic is of use in identifying outcrops. In certain places, the quartzite has been badly fractured and the openings have been filled with quartz veins. In lots 1, 2, and 3, conces- sion VI, Foster township, the quartzite is much fractured and irregular in strike. Most of the quartzite is not distinctive in type; some of it appears to be rather pure quartz and some of it seems to bearkose. There is a high knob southeast of the debouchure of lake Wabagizig, of coarse-grained, cross-bedded, and Icnticularly arkosic material which has been brecciated and filled with quartz veins. The great resistance of the quartz veining seems to have caused it to stand up above the surrounding quartzite as a hill. Similar quartzitic complexes are found along the north shore of laki. Stratton, and in theneighbourhood of Hicks mill in Hallam township. In other places, the quartzite has a sandy fades, the grains are distinct, and there are well-defined, dark a)loured, bedding lines. This facies has a dark colour in some places, and it grades into quartzitic greywacke which is decidedly developed near the contact with the over- lying Bruce conglomerate in lots 7 and 8, concession V, Foster township. In many places, the quartz is very feldspathic and of saccaroidal texture, it weathers into a pale pink, flesh coloured rock, so even grained, smooth surfaced, and opaque, that it resembles porcelain; such a type is on the shore of lake Panache, southwest of the island which is crossed by the eastern boundary of Foster township. Near the same place, much of the quartzite is marked by extremely thin coatings of red hematite be- tween bedding and other planes of opening. In some places cracks are filled with a black specular hematite. In certain parts, the quartzite has unusual facies; for instance, at the point north of the old camp on the south shore of lake Wabagizig, there is quartzite which is distinctly laminated, olive green in colour, with layers of greenish yellow, sandy, fine-grained arkose. A characteristic type of Mississagi quartzite is one made up of irregularly bedded, coarse, clear blue quartz grains, about one-eighth inch in diameter. This characteristic and a greenish colour arc useful criteria for the recognition of the formation in the North Shore region. Microscopic examination shows that the matrix of the conglomerate consists of an impalpable sericitic matrix containing little angular chips of quartz and microclinu 5 mm. in diameter, larger grains of quartz 28 one of quartzite ^drup r£!r' *'r ^-"-"^ Pebbles, includin" cribed. and it suggests tha Loth/ °"'^ ^"^'*^ ^^^dy des- ^^-oe series, andf^^^^^^"^;;;''^!^^^^ ^^P-'^ed before the deposited. A eraniVShW °'^ '''^ Huronian formations were Of thep.-H.oS^Zitr^^^^^^^^^^ 'n^cros.pe to ^ part w.th a"ft^;t1^S7e^.^aVtd'^r'^'' '^•"" ^° "^ -'"'y 'l"-*^. greywacke phase of MtTs^gT' '1": r°*" '" ^'"^ '^" ^P'^'' flakesofbiotite.andscatt3:ri ri^^^^^^ grams are rounded rouehlv anH c„„ J o^ner '^rrite dust. The quartz with "suture" outline" Manv of ?H I * ''^ """"^'' ^'^^^^ «' ^"^'tz irregular crystallog^aphic ^n^^L brTn h": ''T '"^^*''^' '"^^ ^^^ but this secondaryreorwnSn of th '/ ^""^ crenulated margins, as in the pre.uZnTJn'Z^i^cl^^L^''"'' ''^'^^^^ ^ Thickness. renders any close figures imtsS Th ^ ""''''"^ °' ^^^ ^^P^^'^^ formation must be af lea' t TKfec; th iT ,T ""T'"'' "^'^ ^^ ^^e been increased to an indetermi^.hf 'J'^'^' j''^''°"gh these figures have the formation under tirSt. ' ^^ '^' '''^"""^ ^^S^^^her of Origin. graphic .neitv h^ Zl' I- t°^' ^'^""^ P^y^^^^' ^"d petro- and it c. anitTp bbiriTd " fu^ T'^'''''"' ""^ -«>"aceous. been part;, weathe ed at thetl" 'T!;^ ^T''''' ^'''^'^ ^PP^'^ ^« ^ave of the Mississagi Lrlt on wS T ^"^."^""- '^'^'- "PP- P-t ofwellsortedsand aZa' "o.J t T'"u '"■"''^'^' ^^^^'beddcd. and area of considerable rS ' ^' -'^''''" '^P°^'* ^^"^^^ ^-- '^ >-d BRUCE CONGLOMERATE. Stratigraphic Relations. contour. At most exrirpfTh u"^'' ^"*^ '''^''^'y ''•'■eg"'ar in most exposures, there n an abrupt changewithout gradation .Ch.«t«u„ , S»'<*»'y. Geology, vol. II, ,vo4, p. „, 29 -^1 from clean quartzite to very gritty, pebbly, and cobble-rich conglomerate. But there are places in which there is an appearance of alternation ; at one place three quartzite layers alternate with thin beds of conglomerate, and 5 feet below the supposed true contact is a 1-foot bed of greywacke conglomerate. Almost on the line between lots 5 and 6, concession V, Foster township, a place was found where the rock had naturally broken along the plane of contact between the Mississagi quartzite and the Bruce conglomerate. T'le surface of the quartzite beneath the conglome- rate is rough but not ragged; relatively plane, but not smooth or polished; it is rough rather than smooth. The break between the Mississagi quartzite and the Bruce conglomerate is abrupt and positive; therj is no introductory change within the quartzite at this place. Nevertheless, in the north half of lot 8, concession V, of the same township, there is a discordance of dip within the quartzite of 22 degrees, above which the quartzite grades into a sandy we ^hering, quartzitic, almost black rock, which in turn grades into a conglomeratic quartzite. The conglomerate gives place again to white, arkosic quartzite which is conformable apparently below massive, quartzitic conglomerate, in which there are boulders of granite, and pebbles and angular pieces of quartz and quart- zite. In one place a "soled" quartzite boulder 14 by 8 inches in diameter is half embedded in the matrix. In this place the contact appears to be sharp and clean cut, but within ten paces to the east, bedding lines within the conglomerate are parallel in dip and strike with those in the quartzite dipping beneath them. It is not plain that the quartzite inclusions in the conglomerate are derived frora that quartzite which happens to underlie it immediately. On the other hand, it is more probable that most of the quartzite pebbles and boulders found in the Bruce conglomerate are older than the Mississagi quartzite. One quartzite looks much like another, and probably there were several quartzite:. older than the Bruce conglomerate. Therefore, the presence of quiartzite in the conglomerate does not prove that the Mississagi quartzite was eroded before the deposition of the conglcmer-'.te. But a proof of unconformity is the fact that the contact of the conglomerate cuts the strike of the quartzite at a low angle. Distribution. As Professor Coleman reported, in Merritt township the cong!omer« ate covers the top of the escarpment which roughly follows a line parallel to lakes Griffin and Tulloch, and about one-quarter mile north of them. In the west end of the outcrops, repetitive faults have caused a peculiarly irregular distribution of the formation, and, farther west, its non-appear- ance at the surface. Northeast of lake Tulloch the formation is inter- rupted and partly displaced by a diabase intrusion, but it outcrops 30 igneous injecLs iTSly hlddtn't:^ .^^^rr'^^" ^-'ts and conglomerate is t aceabirSht atlt P ? *^"'*u"'^ "^^"P" ^^^ straight south of the n^o^JnirA °'*?'' ^^'^^''ip. On a point Loon lake. Th^^utctS^ t °^~"^'°'"*' '^ ^'^"t the narrows of which is shownt^a sS er^^v I '^J''"*^ "'^ *° ^""*''" '-"'* southwest comer of th^lutrh^? 'f 7"^ Yf °' «>"«'°'"erate in the is shown b^Te outlp of LnJo^ r^' '''''.. ^^**"^' ^''"'-"'t concession I HaC:^i?;^'Th:rouT:;r^^^^^^ f"^ °^ '°* ^' useful as a means of locating °he fau'S T^T u ~"«'°'"^^«^e are to detect, because a ouarteLt ^ i? ,, ^"'^ ^^ ''^'"y ^'ffi'^"'* formation ar^ ^arfy ^^rt£ .^r! '^T* *'""*^'^^ ^^^ ^^ to the bedding In lotT^^i. • ^^f °"'/"d '""^^ sheared parallel crosses the bounda^ of tke 7031 ' ?'"''" *°^"^'"P' «>"«'o'»erate Merritt township^re t liesTa h 'h TT'' "°«heastward into of concession I. as far Ts lak!AL! Z ^ l'"'.' "°'*'' °^ ^^"^ "°^th «"« Striking almos norSeit ano^h^^^' ^T^ '''' '' """ "°* ^ *'^^d. Place soU oTthTlXa:tld ^f'^^^el^^^^^^^ ^^^^ ^- a bay of lake Panarhp Tuu ^ . =>tratton to the most westerly west of the .own.hip „Z^ "^ ^ """' °" ™'' "'""' ""i »™ »!« Character. the si^e" trrrulde^^nS^rHH: °' ^'-V-^'-erate is essentially Places and rough 1^ ^ra.Lt o^h'ef paT'Xt' T"^^ ^" ^'""' average, carries about five boulders rrniT-' • ? "'"S'omerate, on an in diameter for every m square f^.T^f'^ '" '"' ^'■°'" ^ '"^''^^ ' ^ ^°°t 6 inches in diameter are as oleTti.ri '''^'"''- ^"'^^''^^ ^^""^ ' *« pebbles up to 3 inchesTn diame^ '"k!"' '° '""'^ ^^"^^^ ^°«t' ^nd the most part, thetulde's a^^bl^Ltr: ehher^ T'' '"^^^ ^°^ ..ains from .n. h^ ^ ^^ ^ -rtrih;:!^^ s:: 31 dark green matrix. Commonly there is a sort of rough bedding in the conglomerate It does not show thin bedding lines or laminations, but massive stratification which shows especially clearly on weathered faces of the rock. The conglomerate is very irregular in its structure, in some places it is strikingly massive, and in others distinctly bedded. In the massive type, the matrix is drawn away from the pebbles, leaving open spaces around them. The reason appears to be that the formation has been considerably sheared in most parts, and in the process, the pebbles broke away partly from the matrix. Evidently, under the impressed stress, the more plastic groundmass flowed enough to leave a space around parts of the resistant pebbles. Many of the spaces are now filled with calcareous matter and metallic sulphides; possibly the calcareous deposition was the earlier, and precipitated the sulphides from intruded acid solutions, which would account for the present associ- ation. Upon exposed faces, the calcium carbonate is dissolved, and the spaces remain, causing a peculiar, cracked appearance in the conglome- rate. In other places, the matrix is not calcareous, but quartzitic, and there are quartzite layers and lenses in the conglomerate member. Beds ot quartzite are found in all the bands of conglomerate. Under the microscope the conglomerate reveals different fades, as it docs megascopically. A thin section taken within 6 inches of the bottom of the formation is very rich in biotite and colourless mica, the quartz grains are rounded and irregular, with secondary growth resulting in crenulated or suture outlines, and the feldspar grains are much altered. A thin section taken from a quartzitic type of tlie conglomerate shows both rounded and angular qua z fragments, with a few fresh-looking plagioclase grains, and some much altered grains of other feldspar. About a quarter of the rock is ver^- fine-grained, indeterminable, ground- mass. A thin section taken 20 feet below the top of the formation shows a similar compositic if angular and rounded grains of fresh plagioclese and quartz, and grams of weathered feldspar and weathered granite, in a matrix of very fine-grained argillite, with numerous flecks of opaque clay-like material. Near the top of the formation, the boulders are less numerous, and the matrix is very fine-grained. A thin section taken within 2 inches of the overlying formation shows scattered, angular grains of quartz and altered feldspar in a very fine-grained matrix, with much chlorite and sericite. A quartzite member, 25 feet thick, found 20 feet below the top of the formation, contains much carbonate of undetermined composition. It is made up chiefly of rounded quartz grams, fresh looking albitf;, and altered orthoclase grains. The cement is composed of quartz which connects little grains of quartz and feldspar. The quartzite seems to have been partly porous, for cavities which were apparently original Origin. ^^"^•^^^tTj,"^;-^^^^^^ ^'L- ^'^e con„o.erate .a. the deposits, and the heterS^n^l r u • I^^ "^'^*^ character of to the lack of any tns eTS: *'' "^'1'"^' '"^'"^-"^ ^^tify «eem to be continental Xr th^ Sine'^T' '". °"^" '''^^ ^*P°«'t» they are thought to be e ther g^^^^^^^^^ f^'-°'"the.r general character, in a semi-arid climate. The formerlT •°'" '.'"" °' '"''^^"^' °''^'n in 'upport of which he cites aZLlu" "17 ^"^"""^^ ''^ ^^'•'"^. supposedly glaciated. s^^ksSZ^ZZr'H"'''^ "^^ °" ^ the irregular contact of the two formTt; ^"^'^'*^- "« emphasizes also conglomerate lies on thetrunm^X!';:. "^ ^«! °f ^Pinion that the quartzite.. Coleman* t^k XSelSdb. * ' "T*"'*'- '^''^ ^'"•^P correlated the overlying con'^llltlTthTh;^^^^^^^^^^ But the more ntensive work wh.Vh 1,0 1! ^ <-obalt conglomerate, does not support this ZrXiZ''%L^^':ZtZfr ,'" '''^ ^'^^■°" as was thought, for the conglomeratel^^s on .^ ^ ^.'" '"■'^'^^ apparent discordance of dio tZT. -L *• ?^ quartzite with no formations also shows a ntr Jfo J^ TTeV ■)' °"*"°'" °' ^''^ the lack of discovery of striatS h^^H ^^^s'^^'^' ^.ew suffers from thing which is strongly sCs?ve^f'!L'' '"t^-"™ '^' "''""'^ °' ^"y foreign boulders, and theTSroftL "^ T^\*^''^'"« fresh-looking rate..scri^ „p,,. -d%:',-:^ suggests that it may be an a !„!J.1 ^ • ^. "^ '°'='"- ^'« character base of a steep slo^ i^aTe I 70 t^^^^^^^^^ eTr^lr ^^ ^'^^ upon such a well sorted shore depositt/Z m' • ^"^^""^^' deposition distinct uplift In harmnnlvu ? ^'^'^^^ ^"^'"^ite requires should be followed by the normaT en"'' 'r "'''''*' '""^ -"^'omerate stone; but the i-reS^lIritierr h? r,°^'"^'*°"^' ^''^'«' ^"d lim thickness suggest th^t the .H^^ ! underlying quartzite and its great a Postulate/'i,Lnd elet^otX ' 'm I"" ''«'' ^'^^^^>^- ^fte deposition of coarse s^nJsTh.R '^ ^ ^ '"P^*'*'°" "^ «>Pious thin streak of fine ^airdLiS ^^.^f! ™"8'°'"-'-ate is followed by a th^uppositionofStTJJipr^^^^^^^^ «C.«fa..W.H..op.eit.p.l8. • ™rZ-,t^,°°'i:!f~' <"»"«* VOL 23. 1914, p. «, lou wu the only undent lui&cc of th. „,„J^. Z. f b. found, might not look rtnllj.^^"*'"''^""" '•'"he writer. Other tuAce. If they could < The stratigraphic position of the conglomerate su^ests that it may be of glacial origin. Now, the Bruce conglomerate is a xenoclastic conglomerate, that is, it contains materials unlike the rocks upon which it rests; many of these materials have been transported considerable distances. The normal stratigraphic relations of a xenoclastic conglo- merate are, an unconformity below, and a gradation into coarse sand- stone above. It differs from most intraformational conglomerates, because the latter are made up of small transported fragments of the underlying rock, and in nearly all cases, they are thin layers of broken up and slightly rounded, autoclastic materials. Thin conglomerates within a sandstone are not rare, because both are related phases of the same type of deposition, but a xenoclastic conglomerate lying upon hundreds of feet of fine, well laminated argillite, and followed by equally well sorted material, suggests some unusual agency of deposition. An ice-sheet or other glacier deposits xenoclastic conglomerates with stratigraphic relations otherwise anomalous, and it is suggested that this may be nearly as critical a test as the finding of glaciated pebbles. Such stones, in any considerable numbers, are regarded as proof of a glacial origin, because no other process is known which causes this kind of striations, and because present glaciers scratch their inclusions. Similar criteria may be applied to the stratigraphic relations of conglomerates. Present glaciers drop their loads quite irrespective of the character of the under- lying rocks, indifferent'- , in water, at the shore-line, and inland, and no other agency except ice so distributes thick xenoclastic conglomerates. The Slate' conglomerate (Gowganda formation) of the Bruce Mines area shows both these criteria, striated stones have been found, and its stratigraphic relations are anomalous; therefore, arguments in favour of a glacial origin are strong. But the conglomerate at Espanola called Bruce conglomerate is not nearly so clearly of glacial origin, because no glaciated pebbles have been found, and there is an angular unconfor- mity beneath the conglomerate, which is in harmony with the suggestion that it may be of alluvial deposition. The overlying formations, fine- grained greywackes and limestones, apparently conformable upon the conglomerate, with no transitional, beach-like deposit beneath them, are hard to explain whether the conglomerate be alluvial or glacial in origin; and only the xenoclastic composition of the conglomerate is in har- mony with a glacial origin. It is thought that the Bruce conglr ^erate at Espanola is an alluvial accumulation, but its origin is not determined. ESPANOLA GROUP. The Espanola group consists of three formations, a limestone for- mation at the base, a fine-grained grcywacke and slate, and a thin I CoUiiu. W. H.. loc dt.. pp. 21-22. 34 calcareous formation about 300 feet abov. tK . jmestone is called the Bruce Hmestone a^d 1" *'' °""- "^^^ '<"^«' the Espanola limestone. The S^ fnf .^'^ ^PP*^ ""^ « known a. Sreywacke. because in most 1^1 ft hir- r ''"""' '^' ^"'^"°^ places it is too coarse in texturVto t J,7 ?"^^^*' «"^ '" «>">« rotations are useful stratigraphrmlrke«irh- '''^ '^''^ "'"«»*°"« and quartzites. and for tharreasinTh.! 1 u *""' °' ^nglomerates ca«f^.y.where.rpossib,e;ire:\tt^orm\S^ formationfSe''u;ir5rBrL'l° ''r^'"" '^"^^ ^""^^ *»>« area. The on the south. The ^ft I^'T !?"* T'^*"' ""'^ ^^^^^^ those outcrops -cics of the E.panor^;;"t^-- - ^^ ^'"^'^ -ture of^^ places where they are at the sur7a^ " '^"' ^^^P ^™«'on in many Bruce Limestone. - defi^: = e'SSy 1^; Zf -" - - ^n •n only two places in MerritVtoCnZ 'l^'f ' ^^ "*"*^'^* ^^ -- railway on the line between lotsTanH^' '°."8 ^''^ "O'"*'' side of the the west side of the XZ h^ norther' TTT" ^^' ^"^ ^''^ ^t^er on Hne between lots 9 and 10 Al^, rFn' f °^ ^ '^^^'°" "'' "^ar the Brazil lake, about half a m,Wh o/Th '"'u'^'""*^ contact is expo^. i„ every otlr like vnl""'^ '"^ °' ^''^ '^'^^' ^he a fault contact between thrcTnJloStf '7T'"'^ *''^'« '« ^'^''^ contact is drift covered. ~"8'omerate and the limestone, or the is on''^:^:Z Jell's:: rTrL^^^^^^ "'"^^''"^ ■- ^-^" township mill on Ap^y ,a,e. Anoth:r^^?ek ^I^ti""^" 1 ^ ™'*^ "^^^ °^ '^^ above, about one-quarter of a mHe norr30 h '" ^""^ '"""''""^^ ocahty. Exposures in HallamTownsh d ,r. ^''k' ^''' ^^""^ ^''^ «ther there are c ,>od ones. The outcron on tK "^"^ *""''" ^''^*^'- *°^"«Wp fairly dear .Plate II A). InoXTLoH . """"'''^^ °^ «^^'' '^^e is narrow bay which leads oTlf hT^JTT " '" ^''^ "^^^ ^'^^ °^ a Here and there along the fault on the so^Sh ru"'' °^ ^''^''^"^ '^ke. scattered fragments of the 1 mestone show h° ^"'' '^"^'°'"^^^*« bmation of faults and basic intruZs h7' '""^ '" " ^'^^ P'^«« t^e com- in such a way that limestone Is on 2 n ""TT'"^ ^^e series, locally, but these cases are rare. The outcro ' Tu 'f °^ '^' conglomerate places, on account of the faults anSdr^f?'" '^ u° ^"^' ^"^ '" "^^ny come to the surface ^"" covering, the formation does not 35 Character and Thickness. In the Espanola area, the limestone has been found ISO feet thick, but in most places the fault has decreased its visible thickness, and its outcrops nearly everywhere are covered by soil or swamps. It is a red-weathering formation, and markedly thin- bedded. Its surface is lined by the alternation of more with less siliceous layers. In some places the rock is white marble, which effervesces freely in acid, but for the most part it is decidedly siliceous. Under the microscope the rock is seen to be almost 80 per cent calcite, and 20 per cent very fine quartz grains. Other layers within the limestone for- mation seem to be almost free of calcite and to consist almost entirely of very fine grains and chips of quartz and little flakes of sericite. This different mineralogical composition results in the characteristic, lined, weathered surfaces. Origin. The thin bedding of the limestone, and the many siliceous layers suggest that much of it was deposited in shallow water near a shore. The original structure of the limestone has been obliterated by intense metamorphism, and its original thickness probably has been reduced by leaching of the relatively soluble carbonates; thus the exact conditions of its deposition are unknown. Espanola Greywacke. Stratigraphic Relations and Distributions. Conformable on the Bruce limestone there lies a formation of greywacke, consisting of an inter- beddcd series of calcareous and siliceous argillites. This greywacke formation is not conspicuous in the area, because for the most part it is at the bottom of a swamp or some other depression. It is well exposed on the north shore of Griffin lake, and at about 16 chains along the track north from Merritt station. Character. In many places the beds are little more than laminae; most of them are between one-fourth of an inch and one inch thick. The weathered r^urface of this formation is very rough and deeply lined, be- cause th-. " careous layers are much more soluble than the siliceous ones, and a grooved surface results. In semi-arid climates a less well cemented formation weathers in the opposite way; the calcareous layers are resistant,' whereas the sandy layers are freely eroded by the scour of the wind. However, in the Timiskaming region, the Pre-Cambrian, firmly cemented rocks weather according to their relative solubilities. In nearly all outcrops the true character of the rock is difficult to discern. The formation is incompetent to withstand thrust forces, and 1 The KiUdeer niouBtalii* In North Dakota furniah itrlUng example* of veatherlng which ia the anti- theala of that found in the Eapanola (reywacke. There the rocka are middle Tertiary hi age, and probably of very ihallow tntsr and partly tubaerial deposition. The compoeitiQn of the two formations is strikingly rimllar, but In aemi-arid, weatem North Dakou, the limy layers arc resistant, and the sUicsous bands have been scooped out from between them. 36 crumple* readily under compression ; consequently the outcrops are peculiar. The siliceous beds are brittle and relatively resistant, whereaa the calcareous layers are relatively plastic. Under the great compres- » ve deformation which has affected the formations in this area, the grcy- wacke member crumpled into small folds. This folding caused the sili- ceous Uyers to break into pieces, and further deformation forced the plastic calcareous material around the resistant siliceous portions in a very strange manner.' The weathered surface of such a deformed mem- ber has a peculiar, pitted appearance; the more soluble calcareous layers dissolve the more easily, but they have been squeezed and broken out of all semblance to alignment, so that the pits and cracks have no orientation and no orderly distribution. Thickness and Origin. The metamorphosed condition of the for- mation renders an accurate measurement of the member impossible, but It IS estimated to be about 280 feet thick. It is thought to be a shallow water deposit, probably estuarine in origin. Espanola Limestone. Stratigraphic Relations and Distribution. Both upper and lower contacts of the Espanola limestone are gradational into greywackes The lower transiUon consists of an interbedding of dark green, almost black greywacke layers with pale greenish limestone. Its distribution at the surface is wider than that of the Bruce limestone, apparently be- cause the ^ult between the calcareous members and the conglomerate IS one of SI. all throw, and in very few places involved the upper of the two limestones, whereas in most places, it left the lower one unexposed Good exposures are to be seen on the north shore of Griffin lake where the outcrop lies across the large point, and on the west side of the road leading northward from the mill on Apsey lake, about 35 chains from the mill. Outcrops of this greywacke show here and there along the line between the conglomerate and the greywackes in both the northern and the southern exposures. Character. The limestone layers vary in thickness from one-tenth of an inch to one inch. They are not persistent in distribution, nor reg- ular in spacing; in many cases they are lenticular. In some places the layers are quartzitic, and nearly everywhere, siliceous. The limestone IS less pure than the Bruce limestone, and not nearly so thick. It wea- thers to a noticeable reddish brown colour, and in a few places to a bright hematitic red. It is not very readily weathered in spite of its calcareous content, and for that reason, and on account of its red-coloured outcrop, 37 it is eawer to trace than most limettone membert. It seems to owe iu resisUnt qualities to the product of its weathering, an insoluble residuum of ferric oxide. Although the formation is irregular in texture for the most part, certain outcrops by the shore of Griffin lake show a composition of noto- ble homogeneity. Near the water level and close beside the water's edge, the limestone member dips 78 degrees south. The lake water, which the waves splash upon the rock, dissolves hemispherical holes I to 3i inches in diameter, and as deep as 6 inches. The outcrop ha« a strangely jagged, and honey-combed appearance, due to the coalescing of many of the hemispherical holes. Such pits are formed under a peculiar set of conditions. The water splashes upon the limestone, and any little irregularity in the surface serves to catch a few drops, but most of the rock remains free of water after the surplus has run back into the lake. The water in the little holes dissolves as much calcium carbonate as it is able to hold, which indeed is very little; how- ever, anothir wave throws fresh water upon the rock and into the de- pressions, replacing the saturated solution with pure solvent, and so the process continues. The greati the hole which has been dissolvxd, the larger the amount of solvent it will catch, and the faster solution pro- ceeds. The speed of solution is increased not only because there is more water in a large hole than in a small one, but because the ratio of volume to surface increases with the increase of radius of a sphere. In those places where the rock is heterogeneous, the surface is lined with the alternation of soluble and less soluble layers, and the holes grow into grooves, but where the rock is very uniform in composition, the surface of solution is likely to be spherical. Why the holes are hemispheres rather than fortuitous shapes is because an uneven surface of a homo- geneous solid dissolves more readily than a plane surface, much in the same way, and for the same reason, that large crystals grow at the ex- pense of little ones. Points and edges are places of molecular instability; thcrcfo. ;, any irregularities which might have been in the little hole at the beginning tend to become removed by solution. Thus the surface of a hole in the homogeneous limestone grows by solution, and because solution is fastest where it is easiest, it tends to remove first, points, edges, and angles. The ultimate result of such a process is a spherical surface, because a sphere is the only shape which provides equal chances of solution over all the surface, and it is, therefore, the most persistent shape. If we suppose any change in shape from the spherical, some part must come into such a position that solution will remove it faster than other portions, and the change in shape resulting from such selective solution will be back towards the sphere. A spherical solution surface is one in which every point is dissolving just as fast as every other point. 38 f° that the surface Ml a perfectly balanced, .table form. Thu« the hem.spher.cal hole, depend upon the pre«>„ce of a homogeneor^iuWe .Trfa'ce'' f T °^*«ter which has a fairly con.tanTS^u'd T ^k wrface of .uch configurat.on that there i. an intermittent, but rei^t- edly renewed, supply of solvent, without appreciable abrasion Some of the«; rather fragile solution features have not been affected by the yearly .ce shove, although they border the water; but otEe„ ha^ JTb) Th:;::^.^. ";^ "°"'' r' "°* ■"'^'^"^ « «'«-*'' surf c^ (Pia^ 11 B) Those that affect an almo.t level surface haw e«:aped destruc! t.on for the .ce around a lake rides over a low slope without^usineanv marked abras.on. much as glacier, have advanced ov^r neaX flat country w.thout removing all the old soils. ^ Thickness and Origin. The formation varies in thickness from 1 oi correlation. The homogeneous part surely was deposited in .till SERPENT QUARTZITE. This formation consists of two different members which grade into one another. The base of the formation is fine-grained grey^Icke and the^ top^s coar. arkose. The whole formation seems to rec^^atVe^t Greywacke Member. Stratigrapkic Relations and Distribution. This member seemo fo tu. trans.t.nal between the calcareous formations and X^overljnrq art z.te. The bases another .nterbedding of thin calcareous and siliceous aye.-s. very s.m.lar indeed to parts of the Espanola greywacke cHrZ ter.st.c outcrops are along the railway a few chains sou^of Tulloch Take and at Merntt stat.on. In both localities the rock is of the more quart- \T T' ".' ""' ^^"^ ""'"P'^'^- °" ^''^ "-th shore o7>Edern aaroctef. Remarkable features of the upper greywacke are its nprje-marks and mud cracks (Plate III A) whichTe v^^^ell presTrvS mth.n greywacke layers between thicker layers of neaTly clea; "u^ zite. Such may be seen beside the railway just south of Tulloch lake and aga.n a Merntt station. The quartzitic phase clearly has the pre-' n^'T/" '•'' u^'P''" P"'*- ^' '•" •''"^ ^^y ^ith thin! dark bluTh greywacke layers .hewing mud cracks ana cxoss sectionJ of TrreS thickness. The formation weathers rapidly by the conversion of the 99 pale streaks into limonitic clay, whereas the dark layers remain as oui- standing ridges. The whole formation seems to be somewhat calcareciiis, and certain of the lower layers are limestone. The dark bands vary in thickness, from one inch to a small fraction of an inch, and the light bands are from 1 to 6 inches thick; in some places light and dark layers one-tenth of an inch thick alternate for a few feet. The dark layers are fine-grained argillite, and the light bands seem to be very fine siliceous material. An unusual and widespread feature of this formation' is the pres ence of pebbly quartzitic dykes cutting it (Plate III B). Thc-y are on the east shore of Gritlin lake, on the most easterly shore of the north arm of Apsey lake, and on the south shore of Augusta lake about 25 chains southeast from the east end of the portage between lakes Elizabeth and Augusta. The last mentioned dyke is not in the greywacke member, but in the arkosic quartzite which overlies it, and the dykes on Apsey lake are in Espanola greywacke. A conglomerate dyke, like the others, cuts the quartzite surrounding the long narrow lake which is almost in the middle of the north boundary of that part of Nairn township in- cluded in the accompanying map. This dyke is 35 feet wide, it can be followed for 6 chains, and the bearing of its outcrop is due north. It carries granite and quartzite pebbles and cobbles (rounded stones as large as 3 inches and not greater than 6 inches in diameter). Most of the dykes are from 3 to 10 inches wide, and are formed of material like parts of the overlying conglomerate. They carry lenses of small pebbles and scattered pebbles. The pebbles are of quartz and granite, and as large as 2 inches in diameter. The matrix is very gritty, chiefly of quartz grains, but, unlike most of the conglomeratic matrix, it is not sheared, although faults have broken and displaced the dykes. At the Apsey Lake locality, in addition to the dykes, there are frac- ture zones. The fracture zones s«.em to have been closed fissures, and it is thought that the dykes were open fissures which were filled from above, soon after their formation. The presence of these dykes seems to require a longer period of emergence than that required to cause the mud cracks which are so common in the formation. The dykes are thought to have been formed during a fairly long emergence, marking a decided change in conditions of sedimentation and suggesting a sharp break between the formations which are cut by these dykes and those overlying and younger than the dykes. Thickness and Origin. The thickness of the member is put at 250 feet. The greywacke is thought to be wholly of shallow water origin, recording many short times of emergence which alternated with times of depositi'in. > CoUint, W. H.. op. dt.. pp. 13 and IS. 40 Quarttiu Member. Stratigraphic Relations and Distribution. Above a thick transi- tional member the greywacke is succeeded by a well bedded, fairly clean and for the most part fine-grained quartzite. The quartzite has numer- ous good exposures In two bands across Merritt township, and it covers most of the cpntral part of Foster township. Easily accessible outcrops may be seen along the railway just east of Anderson lake and south of Merritt station. The quartzite shows on the shores of the north bay of Apsey lake, around Anderson lake, on the north shores of Loon lake all around St. Leonard lake, on the southwest and on the east shores of Augusta lake, and on the southwestern shore of Elizabeth lake. Character. In certain places there are dirty streaks which suggest a reversal to greywacke conditions; there are also some layers which show very arkosic materials, and grains as coarse as one-quarter inch m diameter. On the south shore of St. Leonard lake there are numerous exposures of highly feldspathic. fine-grained, saccaroidal quartzite which IS finely lined upon weathered surfaces. IV I!^^ ^fmination of the quartzite is its characteristic feature (Plate lu \ 11^ lamination is of different types, and is made noticeable through different causes. It is due to variation in the materials de- posited. The materials during deposition varied from fine-grained grey- wacke silt to clean quartz sand and to large pieces of feldspar one inch in diameter. The most abundant combinations producing lamination on weathered surfaces are quartz and greywacke, and quartz and feld- spar. Tne groTvacke is a dark green material, and the quartz is smoky grey, whereas the feldspar is pale pink, almost flesh colour. Ordinarily the alternation of greywacke and quartz is prominent on account of the difference in the colours of the materials, but the alternation of pale pink feldspar and quartz is not so noticeable. However, the feldspar is more soluble than the quartz, and weathers somewhat faster at the surface The quartz remams solid and smooth at the surface, whereas the feldspar- rich layers are pitted. Most of the district has h. m burnt over, and the charcoal dust has gathered in the little cavities at the rough surface of the feldspar layers, giving a striking lined appearance to some of the otherwise not prominently contrasted feldspar and quartz layers. In other places, the pink porcelainic type of quartzite has lining of dark translucent, blue grey quartz, and opaque pink feldspar, which lining is due to a real colour difference in the constituent minerals. Similarly, in some places a massive, fine-grained feldspathic quart- zite weathers to a patchy appearance, yielding smooth, porcelain-like, highly feldspathic areas, and blotches of grey, rough, quartz bearing surfaces. >ome of the quart.itc which is pule olive green on fresh sur- 41 faces, weathers in yellowish and reddish blotches. The red material is due to weathered iron oxide along bedding and fracture lines, and pale yellow is the colour of the kaolinite resulting from the weathering of feldspar fragments. This aluminous material is an insoluble residual weathering product, whereas the iron is more soluble and is leached from the quartzitc ?nd deposited in the bedding and fracture cracks. In one plao? along the south shore of St. Leonard lake there is a thin (6 inches thick) layer of conglomerate in the quartzite. There are many small pebbles of quartz, granite, and pieces of mudstone in the arkosic rock. Another feature characteristic of some parts of the Serpent quartzite, is limonite-like spots on the surface of the quartzite. Examination shows that there is a considerable content of carbonate in the quartzite, which weathers to a characteristic tan cclour. This type of quartzite is well exposed at Merritt station, and alon^ the track west of the northwest shore of Loon lake. Near the top of the formation, there is pink weathering arkosic quartzite, interbedded with dark coloured quartzite and siliceous, slaty greywacke. It is the tan-flecked, felds- pathic, saccaroidal, separate-grained (in contrast to the recemcnted quartzite) type of Serpent quartzite which is cut by a conglomerate dyke on the southwest shore of Augusta lake. There is another variety of this quartzite along the portage between lakes Elizabeth and Augusta, which is fine-grained and feldspathic in some layers, and sandy in other layers, and weathers to a very pale violet tint. Under the microscope the Serpent quartzitc is seen to be feldspathic, much more so in some places than in others. One chip taken from near the top of the formation is very coarse arkose. About 75 per cent of the thin section is feldspar, about 20 per cent quartz, and the rest carbonate. The arkose was originally loosely compacted and the carbonate fills original voids between the grains. The grains are rounded and large, rather uniform in size, composed of quartz, plagioclase, and microcline. Another thin section of similar arkose shows strained quartz grains, and broken feldspar grains. The grains average about 1 mm., although there are some of feldspar 4 mm. in diameter. In this section, as in many others, there arc some areas of granulated quartz and feldspar filling spaces between the grains. Another section taken from pink, saccaroidal arkose shows a rather different type. The grains of feldspar and quartz are of irregular shapes and sizes. Some feldspars are weathered and others are unaltered, and some of the feldspars are clearly invaded by little veins of secondary quartz. In this specimen 60 per cent of the rock is feldspar. Another type is more quartzitic, and contains at least SO per cent quartz. Its feldspar grains are partly replaced by quartz. The quartz grains have made considerable secondary growth; they have suture 42 outlines, they invade feldspar grains, and they interlock like the quartz grams of the M^ssissagi quartzite. Unlike the other quartzite. however, there is a notable amount of carbonate in scattered rhombs and it is that which causes the tan spots on weathered rock faces. Under microscopic examination the Serpent quartzite, or arkose, « not at all like the other quartzites of the region. It is notably rich in feldspar and characteristically marked by the occurrence of microcline It contains carbonate crystallized among the quartz and feldspar grains.' The clastic grains are commonly fairly well rounded, and not markedly weathered. Spaces between the large grains are filled with fine quartz and feldspar sand, and very little ferromagnesian clastic material The arkose was probably loosely compacted; for there has been room for enlargement of quartz grains, not in all cases at the expense of the feldspar grains, and many feldspar grains have been sheared across and displaced, which could not have happened unless there was space to accommodate the movement of the offset parts. The arkose is almost free of senate, and in general it is less metamorphosed than the Missis- sagi quartzite of the same area. Thickness and Origin. In Merritt township the formation appears to be about 1,600 feet thick, but the overlying Gowganda formation. which IS the next formation to be described, is on an erosion surface. and much of the formation was removed ' - that place. In Foster township the formation gives evidence of being possibly 8,000 feet thick includmg a great upper member of pink arkose which is not found in Merritt township. In general, the formation shows a gradation from very fine-grained clastic material to coarse, feldspathic ingredients, it is natural to suppose that it indicates an ancient shore-line contiguous to a con- tmually rising land of considerable relief. The constituents of the arkose imply a close source of microcline feldspar, presumably a granite mass, poor in ferromagnesian material. The nearest granite now exposed IS about 9 miles to the northwest and it contains no microcline, so far as known. However, it seems possible that orthoclase in weather- ing develops the typical microcline twinning,' and the writer concludes that the Serpent arkose was derived from the pre-Huronian pink gneissic granite described on page 22. COBALT SERIES. In the Espanola area the Cobalt series consists only of the Gowganda formation. It has three distinct members; the bottom of the formation IS a basal conglomerate, at least in part, which grades into a well bedded slate, and that in turn gives place to a massive, slate conglomerate which looks like tillite. • Barlow, A. E.. Gtol. Surv.. C«n., Ann. Rept. voL X, pt. 1. 1»7. p. 198. GOWGANDA FOk^ ..iION. 3 Stratigraphy Relations and Distribution. Unconformably on the Serpent quartzite is a conglomerate formation which is thought to be the equivalent of the Cobalt conglomerate of Cobalt, and the slate conglomerate of Bruce Mines district, '^his formation is believed by several who have worked in the region to bt! of glacial origin.' In the Espanola area, this conglomerate appears in an east-west area 5 miles long, within one-quarter mile of the south boundary of Merritt township, and in another area IJ miles long and one-half mile wide, nearly in the middle of concession II, Foster township. The latter is near the middle of a southwesterly plunging syncline, which is cut off on the south and southwest sides by faults; the structure accounts for ifs isolated position and small extent. In this synclinal exposure 1,350 feet of the Cobalt series is exposed, consisting of 180 feet of irregul- arly bedded conglomerate and quartzitic layers, 450 feet of greywacke, part of which is well bedded slate, and 400 feet of massive boulder slate conglomerate, topped with fine-grained pink arkose which is exposed only for a thickness of 20 feet. Although the succession is cut out by faults, this pink arkose is thought to be near the top of the conglomeratic series and possibly the base of the overlying Lorrain quartzite,* which is found a few miles south of this area in La Cloche mountains. Character. The characti of the formation varies from place to place, and this is especially true of the bottom part. It seems to be clearly unconform- able everywhere in the district upon the Serpent quartzite, and from the difference in thickness of the Serpent quartzite remaining in Merritt township, and that remaining beneath the conglomerate in Foster township, there must have been an important erosional relief to the Serpent quartzite. It is unlikely that there could have been a very great differ- ence in the thickness of original deposition of the quartzite within about 6 miles along the strike. In Merritt township, the conglomerate lies upon the lower part of the Serpent quartzite, which is almost white; whereas, in Foster township the underlying rock is pink arkose, a phase of the Serpent quartzite which is characteristic of its upper half, and especially of the top 1,000 feet. I Colemui, A. P., Am. Jour. Sc, vol. 23, 1907, pp. 189-192. BuU. G«ol. Soc. Am., vol. 19, 1908, pp. 347-366. Jour, of G«ol. vol. U, 1908, pp. 149-158. CoUiM. W. H., Geol. Surv., Can., Mem. 33, 1913, p. 58. WDsofi, Motley E., Gcol. Surr., Can.. Mem. 39, 1913, p. 97. Jour, of Geol. vol. 21, 1913, p. 141. i CoUint, W. H., Geol. Surv., Cu„ Mut. BuU. No. 8, 1914, p. 23, 44 Near the southwest corner of Merritt township, a slate conglomerate lies unconformably upon the quartzite. The quartzite is white, and vitreous in character, dipping 70 degrees south and striking north 81 degrees east. The line of contact runs north 105 degrees east. The base of the conglomerate is rubbly, beach-like in character, grading up mto a massive greywacke matrix in which there are large boulders, as large as 2 feet in diameter, heterogeneously distributed throughout the mass. About 100 feet east of the last place mentioned there is no beach type of conglomerate to be seen; the greywacke boulder conglom- erate, carrying a few pockets of quartzite, lies upo'. a surface of quart- zite. One thousand feet still farther east there is another beach, or a continuation of the first beach, 100 feet above the base of the greywacke conglomerate. Then for 1,000 feet the contact of the quartzite and conglomerate is very well exposed. In most places the conglomerate is very pebbly and bouldery near the quartzite. Many large pieces of granite and quartzite lie upon the surface of the Serpent quartzite. The bottom 5 to 10 feet of very coarse conglomerate is overlain by about 50 feet of cobbles, grit, and pebbles which look like beach deposits. They lack marked lenticular forms and cross bedding lines, but they are metamorphosed, and such features may have been partly effaced. At the east end of this contact its bearing is north 125 degrees east, and at the west end north 80 degrees east. This conglomerate grades into a slate member above it. The contact of the two is conformable and gradational. Mud was deposited while yet boulders and pebbles were occasionally being dropped in the same basin. For instance, in one place, one granite boulder 4 feet by 5 feet in diameter was found lying at the base of the slate formation with the slate bedding lines around it like flow lines. This slate is about 400 feet thick. Above it there is another conglomerate, 330 feet tliick, which carries many quartzitic layers, pebbles, and boulders. There is next about 30 feet of slate, and above that is massive greywacke with a few scattered pebbles in it. It is not known how thick this last grey- wacke member is. Work in Mackinnon township would probably lead to much additional information in regard to the nature of this formation of slates and conglomerates. Between lots 8 and 9, concession I, in Merritt township, the contact between Serpent quartzite and the slate conglomerate is visible. The quartzite strikes north 88 degrees east, but the contact runs north 79 degrees east. The contact appears to be a clean plane, with a boulder bed 8 feet thick on the surface of the quartzite. The boulders average 6 inches in diameter, they are well rounded, and for the most part of granite and schist: quartzite boulders .nrc rare. They are so thickly set, that boulder rests against boulder in many cases, and the matrix is 45 coarse grit and pebbles. Above the deposit of boulders there is a dark coloured quartzite carrying many lenses of pebbles and boulders for 35 feet, above which it changes into that pebble-rich type of unbedded conglomerate with a sandy matrix, in which boulders are less common. In another part of the base, near the same locality, there is a pebble deposit at the contact with the quartzite, and boulders are abundant above the pebbles. Thus in general, the bottom of the conglomerate seems to be well bedded and irregularly stratified. The middle is predominantly massive, but the upper part of the member is well bedded, and grades by loss of boulders, pebbles, and finally large grains, into a clean slate. In this place the formation is much sheared, and the bedding is not everywnere distinguishable, but this part of the formation is not a heterogeneous mass. In its deposition water action has had a prominent part. In Foster township, about 6 miles away, the group is similar in character, although it is different in detail (Figure 3). The west end of the outcrop shows the following succession: upon pii^k arkose the Gowganda group lies unconformably. The top of the pink arkose is apparently 8,000 feet above the base of the Serpent quartzite, of which it is a part. The base of the Gowganda group is a conglomerate of worn cobbles, and angular fragments of rock. It is a basal conglomerate only about 5 feet thick. It is followed by about 100 feet of conglomerate which is not at all like a beach deposit; there is no appearance of bedding, the boulders, cobbles, and pebbles are heterogeneously distributed both laterally and vertically throughout the matrix, and the matrix is a greywacke with little quartz grains scattered through it. The pebbles are of greywacke, schist, granite, and quartz. This conglomerate is suc- ceeded by a group of pebble and quartzite layers, and partly stratified conglomerate, about 80 feet thick, which grades through siliceous greywacke, into a finely laminated, dark green, grit-free slate 450 feet thick. By being less well bedded and more siliceous, and, higher up, by the addition of little rock grits, pebbles, cobbles, and finally boulders, the slate gives place to a massive greywacke conglomerate much like the slate conglomerate near Bruce Mines. It carries many pink granite boulders; the matrix is dark green greywacke, yet there are so many red granite inclusions, that the whole rock looks red from a distance of a few hundred feet. The matrix weathers more readily than the granite, and the boulders stand out upon the weathered surfaces of the rock. In many places there are so many boulders in the rock, that an area of 100 square feet includes five boulders more than a foot in diameter. In most places there are not so many large boulders; 1 to 100 square feet is about the average distribution of boulders as large as one foot in diameter. The inclusions are of all sizes from finest sand to large 46 •••"••Si t ■> « ** • • < • • •• o^; • ^ fhor/jf ktddtdyun ynytmcl».\ Fiif piitk nUjptr trtoM. Bouldtr eonglomorttm . MUMiifulT Matrix ywjitmml» ecntmmity maiy tl»fbtnmii indiaiona oCnJ Mndaton^. gmiitmbouUtnaitiijrymtclit matrix. Shlj oonghnfrtta . no jwh/, UnUarmii fortius Massif conghmenta.fiwslttu Itfmrs, sandy. Gradation iand cf siliceous greywacka fiiafy laminatad, dark frmmn yr^wadm. Massi¥a , 1 yraywacka. ^rtfybaddadccnglomarate. Oaatth Baach Caalomarata, siliceous graywadia matrix t^Ulatefyr^n,ael(e.schiit,jranite.aipegmat.t.c. But quartz diabase is composed of oligo^^lb^ ^stuck through a nutrix of ferronugnesiTlnera HnT^W pepnaute Dykes of gabbro. commonly called olivine diabai.^ with the diabase masse.. In Nairn township . gabbro dyke h^;uSra U^ debase mass. Although the gabbro is tSstly in r^r^Jres. it forms a large mass one-quarter mile south of St. Leonard lake ThS ohe^2^. T"?' ■^"'*. u ""''^'''' «'^y- Within it theiHre rZ^ phenocrysts of andesme-labradorite. but apparently no olivine. S^ fore there are mjecuons of diabase, both quartz-free and quartz-beari^ gabbro. and gabbro porphyrite. s""" oeanng, Quarlt Diabase. Essential minerals and their approximate percentaires are:ohgodase-albite.40;quartz.20;orthoclase.l5;'aSdalteredh':^X 20 Accessory mmerab are andesine. microcline, calcite, ferrite zoisite chlorite, and seriate or kaolin. ' **' lathJ/JS'""'^.". """""'^ '^^^''- '^^' PJagioclase feldspar is in ath-shaped crystals separated by a matrix of micropegmadte and ^TZZ7 ?"'?'• ''^' P'"^'^'^'^ ^^ b-- veryTch alter^ ^d absorbed by the micropegmatite. The orthoclase interS S^ ^Sh t ' ^"^--^.^'^l^^ ^^"^ to be the result of a diabase havJ^ kth K '1^°"' '^'"""*'- ^'"" ^^ hornblendes and the plagbS laths have been much altered, it is not clear why the orthocul Tn t^ mi^opegmatite is unaltered if it were almost syn^netic "TtT^p" t iTss Tt is oTl^"?- ^^^ 'l•«^^"-^ intent is likewise anomalo^ unless It IS of secondary introduction. Contact metamorphism between diabase and siliceous sedimentary rocks seems to have resulSd i^Z sSnTtii ^^htrr" °' '^n' ^^ ^•"-' ^<>-"«wn uch ing lase the jio- ous ;en his ro- ing )ar tly J Diabase. Essential minerals are plagioclaae feldspar, varying from andetine-labradorite to oligoclase-albite, in amounts varying from 2S to 65 per cent of the whole rock, and green secondary hornblende, varying from 70 to less than 20 per cent of the rock. Accessory minerals are magnetite, apatite, and biotite. Common secondary minerals are chlorite and quartz. The texture is ophitic and diabasic in some speci- mens, the hornblende is in hypidiomorphic crystals with feUspar in the spaces between them; and in others, feldspar laths penetrate the horn- blende matrix. The texture is commonly granular, and marked dia- basic texture is not common. The quartz is in small irregular grains with branchiate shapes invading both ferromagnesian and feldspar minerals; it fills spaces between the other minerals, and has the vermi- cular form of micropcgmatite. OUvine Diabase. Essential minerals and their approximate percent- ages are : labradorite, 70; olivine, IS ; and augite, less than 10. Accessory minerals are brown biotite, magnetite, and apatite. The texture is markedly diabasic. The plagioclase is in laths, with the spaces filled with augite; this, in turn, is penetrated by a large amount of olivine in hypidio- morphic grains. In the augite there are also grains of biotite and magnetite. In all other minerals apatite crystab are automorphic. The order of crystallization seems to have been, apatite, feldspar, olivine, biotite, and augite. Gabbro Porphyrite. Essential minerals are phenocrysts of andesine- labradorite, other essential minerals are too fine-grained to be distinguish- able. Secondary and accessory minerals are. calcite, titanite, pyrrho- tite ( ?), pyritc, chlorite, sericite, magnetite, hematite, few small saus- suritized plagioclase phenocrysts, and propylitic ferromagnesian minerals. The groundmass is almost black in colour, very fine-grained, and of felty texture. Contact Metamorphism. Absorption. The physical effects of the intrusions upon the sedi- mentary rocks are not great, but the chemical alteration is marked. The dark-mineral radicals of the basic dykes and sills have penetrated the quartzite for a considerable distance from the apparent true plane of contact. The manner of this penetration seems to be shown by numerous instances of partly or wholly absorbed quartzite inclusions in the dykes of the district. Instances of this are to be found IJ miles northeast from Thessalon station, where a diabase dyke is so closely set with quartzite inclusions as to be an agglomerate. The quartzite fragments are deangulated and assimilated to such an extent that they have hour-glass and other re-entrant curved forms. Fourteen chains south of mile-post 55 on the Canadian Pacific railway, just west of Blind River town, the diabase shows numerous inclusions of quartzite. The 52 quwtate giw. evidence of partial Miution by its rounded outlines, and by a iort of ghct outline to which the quartzite originally extended, but which lies now in the diabase. Other quartzite nuuaes seem to be •potted through with a few crystals of hornblende, possibly the re- combination of impurities of the original quartzite, but since gradation into much darker borders around the edges is very common, it looks much more as if the ferromagnesian radicab had penetrated the quartzite by chemical diffusion. Furthermore, there are some places where the hornblende crysuU are very large, a few inches in length, and scattered throughout the quartzite to such an extent that the sedimentary rock tooks like a diabasic igneous rock. A striking example of this is to be •een in the neighbourhood of Long Uke mine, a few miles south of Naughton. 1 n some places the quaruite has been so altered by the basic intrusion, that under the microscnpe there is no sign of its original clastic character, although it retains traces of the quartzitic bedding lines and the fracture common to most of the quartzite of the district. It is scarcely to U^ expected that so basic a rock as the diabase could be intruded mto almos* pure silica without a considerable amount of fluxing taking place; but the question is, how great is the extent of this action ? Although not nearly enough investigation has been done to answer this question, field observation suggests that the influence of the quartzite and the diabase on one another nowhere extends more than 12 t . 15 feet. Nevertheless, in such places where the dyke is glass next to ihe intruded wall rock, contact metamorphism is merely a phvsical cli .nge. mylonization of the intruded rock along the plane of contact with no apparent chemical alteration. ' Microscopic Determinations. In order to test the question r.f a molecular diffusion at contacts, several rollections of rock chips were made across contacts of diabase and quartzite. and of diabase and grey- wacke formations in Espanola area; 'hese specimens have been studied under the microscope. A series of specimens taken across the contact of diabase and arkosic quartzite seem.s to show penetration of the diatiase by q.i , and migrat- ion of basic radicals from the diabase into quaruit . \\ n the diabase the feldspars and metasilicates are partly replaced by ..regular segreg- ations of quartz. Quartz is in branchiate, ermicuhir form, and in irregrular grains of botryoidal shapes, invading both felspars and horn- blende crystals. In some cases, included nuartz is not entire! absorbed and forms glomero-phenocrysts with plai margins bet^veen individual grams but with very irregular exten r b. rders. In other cases quartz IS m the form of micropegmatito. TI. micropegmatite fills spaces between the diabase minerals, -A eve. :^..« ^ have absorbed parts of them. SI In a thin aectbn collected near a contact of grcywacke and diabase, the diabase consists chiefly of oligoclaM-albite phenocrysU (Ab>»Ani) in a nticropegmatitic matrix. The plagioclase laths are partly resorbed by the pegmatite. The phenocrysts are saussuritized, but the pegmatite of quartz and orthoclase is not altered. If this is a contact metamorphlc effect, lime-soda feldspar has bt-en replaced by silica and potash feldspar, and the micrnpeKmatite is of cpigenetic origin. It is possible that the saussuritization is a change ot long stmding, preceding the crystallization of the micropegmatite, and that it took place before the complete solidi- fication of the diabase; if so, the micropegmatite is probably syngenetic; however, the presence of quartz in irregularly shaped grains points to the introduction of swrne quartz, and it is thought that the micro- pegmatite also is epigenetic. Another section of quartz diabase, taken from near the contact of an intrusion into siliceous quartzite and granite, shows automorphic cr>-stals of little altered oligoclase in a granular matrix of quartz-ortho- cla.se pegmatite, and some much altered ferromagnesian mineral (probably originally augite, now hornblende, chlorite, sericite, calcite, and epidote). The micropegmatite appears to be in granular units, within which the arborescent stringers of interwoven quartz and feldspar are very minute. Each unit seems to have the form of a feldspar crystal in spite of its quartz-orthoclase composition, and each grain, in regard to both quartz and feldspar, is an individual crystal, apparently unconnected crystallographically with the quarts or the orthoclase in adjoining grains. E. S. Bastin' has described a -imi! r case of micropegmatite in the pegmatites of Maine. He describes the feldspar crystals as feldspar "brushes." Then, is no doubt that micropegmatite forms in the interstices of granular rock as the last, eutectic crystallization of the quartz diorites of the region. Collins' has described this type of micropegmatite in rocks of Nipissing district, and recently N. L. Bowen' has discussed fully the chemistry of such a process. Nevertheless, in the case here described some of the micropeg- matite seems to be an effect of contact metamorphism; for the thin section shows not only micropegmatitic texture, but also cataclastic materials, all of which are quartz and feldspar fragments, some of which appear to have been reorganized into a micropegmatitic intergrowth, although none of the pieces is a fragment of micropej;matite. The development of micropegmatite appears to be younger than the cataclastic material, and it is thought tc have been fornn d by interaction of the acidic rocks with the basic intrusion soon after injection took place. ■Banin. E.S.. i nited States Gcol. Surv. . BuU. ^ i.i. ivll. p. ii. •CoUlni,W. ' -!. vol. V. 1910. pr ♦MJ. •Bowen, N ■ XVii: Sui-ri" • nt, p. 40. 54 In addition to tiiose large crystals of hornblende which are in quartzite near contact with diabase, under the microscope it is seen that there are many small crystals of pyrabole which separate and surround many of the quartz grains, and the quartz grains are speckled with small pyrabole fragments or crystolites. In the quartzite there are some segregations of pyrabole, and these segregations carry quartz pheno- crysts which seem to be the fusion or crystallization into one crystal of many small fragments. Along the borders of these pieces, pyrabole fragments remain behind, although in many cases the line of separation between quartz fragments is obliterated. Thus it happens that small pieces of hornblende and sericite (?) are stranded within a quartz crystal. Around the borders of the quartz small pieces are oriented not quite parallel to the main crystal's growth, and it is supposed that they are brought gradually into alignment by crystallizing forces. In more clastic specimens, some quartz grains show enlargement by crystal growth, but the parent grain is full of inclusions, whereas the added border is clean quartz. Possibly some of the ferromagnesian minerals within the quartzite are the reorganized impurities of the quartzite, but there is no doubt that there has been a considerable transference of dia- base minerals into quartzite near the plane of contact. At the contact between diabase and greywacke, and even within the greywacke near the contact, there are segregations both of siliceous and of basic minerals. Hornblende seems to be in very small, unoriented frag- ments in the basic parts, and acid radicals form small, quartz-orthoc! ~ glomero-phenocrysts . it granular micropegmatite. In the micropegmatite there are distinct, interlocking granules of quartz and orthoclase. Many of these glomero-phenocrysts of micro{)egmatite are clearly secondary, for bedding lines of inclusions run through them. Micropegmatite in the diabase, even when replacing plagioclase feldspars, can be explained as possibly primary, but it seems necessary to grant that micropegmatite in 1 le sedimentary rocks is epigenetic. If it is epigenetic in one rock near the contact, presumably some of it in both is not an eutectic cry- stallization but an absorbent, contact metamorphic effect between the quartzitic sedimentary rocks and the basic intrusions. W. S. Bailey' reported that the quartzite at Pigeon point, Minnesota, is intruded by gabbro, and altered at the contact into a red, feldspathic rock (commonly referred to as the "red rock"). Quartzite inclusions in the gabbro have borders of the same kind of material ; evidently it is a contact metamorphic effect. Within this red rock there are irregular and club shaped masses of quartz, and micropegmatite. The writer is indebted to Professor F. F. Grout, of the university of Minnesota, for the opporlunily of examining several lliin secliuns of tiie rocks at Pigeon < Bailey, W. S., United Sutn Gcol. Surv.. B'lll. 109, 1893, pp. lOt-102. 55 point. In the red rock, collected at the contact of quartzite and gabbro, there » granular micropegmatite like that described by the writer, each feldspar grain controlling the quartz within it. In the gabbro, quartz is included or absorbed in the form of irregular grains, and in vermicular and branchiate masses filling interstices between feldspars. Within the quartzite there is the reorganization of little quartz and feldspar grainr into primitive micropegmatite. Thin sections made from specimens collected by Professor Grout from the contact of gabbro and lake Superior sandstone at Duluth show similar things. Within the sandstone there are granular segregations or replacements of micropegmatite, and in the gabbro there are quartzitic replacements about the feldspars. Therefore, it appears that micropegmatite is not only an end product of crystallization in quartz-diabases, but that it is a phase of absorption in contact meta- morphism. Quaternary. GLACIAL. Pleistocene formations are scanty in the Espanola area, but there are some glacial deposits in the northern part. On the north side of the wagon bridge at Espanola Mills, there is a deposit of glacial boulder clay at the edge of the lake beds, which lie against and upon part of the glacial deposit. A few chains northeast of the corner between the trunk road and the road to Espanola station, there is a gravel pit, in what looks like glacial outwash, overlain by a few feet of clay. POST-GLACIAL. Lake Sands. The glacial deposits proper are not abundant, but deposits in the lake which followed the ice invasion are widespread. The greater part of the northern half of the area is covered by a water-laid sand. At Espanola Mills there is at least 60 feet of sand above bedrock,' and in the young valley of the Spanish river, a mile southwest from Espanola Mills, there is a 60-foot exposure of sand. The sand-plain seems to be the result of a valley having been filled with lake deposits, for the hills rise from the flat surface abruptly, without the usual basal slopes. Judging from the sand exposures just mentioned, the bottom of the valley must be several scores of feet below the present surface, and it may be much lower in some places. About one-fourth of a mile south of the wagon bridge across Spanish river, there are several large dunes on the sandy plain. Although now covered with grass and the stumps of spruce trees, the dunes retain their crescentic form, concave towards • For thh Informatloa Uu writer l< indebted to the courteey of the mane :-er of the Spanish River Pulp ud Paper miUi. Theae data were determined during baring operationi in ' > inexion with the buUdlug of the plant. S6 t he southwest. A few chains west along the road from the north end of the wagon bridge, one may see the shore deposits of the old lake. They lie at a higher level than the glacial till near the same locality, and partly upon it. Probably, these deposits of sand were laid down in Pleistocene times before the ice-sheet had retreated far enough to allow the pent up waters to escape. They may have been deposited during the Algonquin- Iroquois stage.> Stratified Clays. On the north side of Spanish river, between the two bridges, there is a thick band of stratified clay (Plate IV B). It is notable in that it carries many strange inclusions resembling concretions. It is inter- laminated clay and sand like the siliceous, Huronian members, and carries numerous pebbles and boulders in its well-bedded matrix. Many of these are glacial, and are confined to the lowest 10 feet of the deposit. A similar case has been reported by Collins,' who states that the Saugeen beds near lake Timiskaming are stratified clays which carry well-rounded large pebbles in a well laminated matrix. Collins calls attention to the striking similarity between these deposits and some of the boulder-bearing laminated slates of the Cobalt series. In the Espanola locality the section exposed is 54 feet thick, and in the lower part there are numerous ripple-marks, many of which are overturned in contemporaneous drag folds. One layer was seen which showed these little drag folds over- turned in opposite directions towards the middle at each side of the deposit. The clay lies between two hills, which are thought to have afforded the conditions of shelter necessary for the deposition of the fine material composing most of the deposits. Some of the boulders are thought to have been floated in by ice, and others to have rolled down the steep hillsides out on to the frozen surface in winter, and to have dropped through to the bottom in the spring. Ma'lekor or Imatra Stones. Attached to some of these rocks in the bedded clays thcl-e are smooth argillaceous masses. There are also concreticii-like masses of clay which are not connected with rocks or any other apparent attachment. They arc not concretions in the sense that a ferruginous concretion is the chemical concentration of a cementing material, which, in most case? by its dehydration, forms a hardened unit. They seem rather to be the indurated remains of a viscous fluid which was covered by fine materials. It is well known that clay and water may be mixed in all ' Frank Levcrctt and F. B. Tay:ar, U..S. Gcol. Surv., Mon, 5J. 1915. p. 453. •CoUlnt, W. H.. G«ol. Surv., Can.. Mem. J3, 1913, p. 54. 57 proportions, and in tKe ceramic industry such a fluid mixture is called slip. In plastic clays much of the water is in combination with the aluminum oxii). and silica, forming kaolinite (A]tQi.2SiOi.2lIiO) and higher hydrates; such clays may be air-dried to hard and strong casts, and it is done continually in pottery manufacture. Now, the for m of the inclusions suggests that they were formed from the localization ' vik-o'w clay slip which was buried first in the silts, and later induratet. ■/ *jie loss of associated and loosely combined water. Some of these inclusions show plainly that they ^ere rolled in the water while they were still very plastic. Others show that they were not moved after they first accumulated, and they bear upon their surfaces peculiar, irregular, little ridges oi unknown origin. These inclusions owe their cementation part'y to the presence of calcium carbonate; but they owe their forms to the fluidity of the clay slip from which they seem to have hardened. Such inclusions are known as marlekor (singular marleka) or imatra stones.' Erdmann* described similar "concretions" from the glacial clays of Sweden, and mentions that Kjerulf supposed that such marlekor were rounded by the agency of water, and then buried in the mud. But Erdmann, himself, does not follow Kjerulf -n this belief, nor does he agree with Sars that they are formed around :2 remains of shells and fishes; Erdmann had not found any such orgraic nuclei as those which Sars had reported from Norwegian localities. However, Liesegang* quotes Richters* as authority for the report that in each centre of a double marleka there was a very well preserved snail shell; the shell was not altered, and the cementation of the concretion had come about by the addition of calcium carbonate from without. This is the means of for- mation favoured by Erdmann, although he does not lay stress upon the necessity of a nucleus. Liesegang' thinks the marlekor are chemical phenomena, but he fears there is no probability of their being explained. By him they are not thought to be concretions due to chemical diffusion, because most of them lack the nuclear centre requisite for such formations. Wilson* has described similar phenomena from the Kewagama Lake area in Quebec. He thinks that they were formed in place by the solution and redepositing action of fluctuating ground water, and that they are true concretions of lime carbonate with a certain amount of included foreign matter. Erdmann cited cases of n.ar'.ekof which carr>- 40 to > Pinot, G. F., UcB. d< I'Acmd. Imp. da Sdencci de St-Petenboun 1M9, *ni "Rcckercht^ phytiquet lur Id pienc* d'lmatra," 1840. 1 Erdmaan, A., Bxp<»( dci formatioM qiMternaira de la SuMe, Stockholm, tS«S, pp. Ml. • Liewdng, R. F., Gcolof iKhe DUIuiionen, Dradcn and I.eipxig. 1013. p. IS9. •Rkhtcn. F., Uebcr Marlekor, PromethcM 23. 697 (191]). •Lioesafitt. R- F.. op. dt.. p. 158. • WItaan, M. E., Gfol. Surv., Can., 1913, Mem. 39. p. lOS. and T ite XXVli. 58 66 per cent caldum carbonate in a matrixwhich contained only 0-5 to 3per ratai^" ""^stance. »>"» the inclusions at Espanola are notnearlyro It seems evident to the writer that not all such inclusions are chemical «ncret,ons and he foUows Kjerulf in beUeving that many of them were formed, and rolled about by water action, while they were still in a plastic condition and before they were covered by the mud and silt which formed dieir present matrix, Plate V shows the flow lines in the marie- f^L-Tr T^ '^° "°' P™"* ***** °° "»"'«'«>' a™ true concretions formed by the segregation of lime from the surrounding clay; but .t ^thought that these particular specimens ate the dehydrated and cemented products of viscous day slip. CHAPTER V. STRUCTTURE. GENERAL STRUCTURAL CONDITIONS. The Bruce series consists of about 1,000 feet of greywackes, con- glomerates, and thin limestones, underlain by about 4,000 feet of quart- zite, and overlain by possibly 8,000 feet of quartzite. In some place- several thousand feet of the upper quartzite was eroded before th deposition of the overlying Cobalt series. The Cobalt series consists of about 1,000 feet of conglomerates and slates, overlain by several thou- sand feet of quartzite. This Cobalt quartzite, called the Lorrain quart- zite, is not known to be in Espanola area, but its great thickness a few miles to the south in La Cloche mountains leads to the supposition that it was originally deposited over the Espanola area. These Huronian rocks rest upon an ancient basement of schists and greenstones, and they strike from north 40 degrees east, in most places, to north 90 degrees east in the central part of the area; the dips are high, differing from SO degrees south to vertical. With outcrops about parallel to the strike of the rocks, three major faults and several minor faults break up the terrane into steeply tilted slices. Although the incompetent limestones and greywackes show intense drag folding, the strong quartzite members are little warped, and they have controlled the major structure of the region. However, in the south-central part of Foster township there is a southwesterly plunging syncline within which lies an outlier of the Gowganda format on, and there is still more folding farther south (see page 67). Tiie pre-Huronian sediments are greatly metamorphosed, but their exposures are not large enough in this area to give much idea of their structure; however, their strikes are mostly east and west, and their dips are about vertical. Their present deformation seems to have been almost completed before the period of diastrophism which caused the structure of the overlying Huronian rocks. SUMMARY OF EVENTS. The Bruce and Cobalt series form a competent terrane which it is thought was first slightly warped by a growing thrust from the south, and as this force gradually grew the essentially rigid quartzite members broke. The nature of this first yielding to pressure is that of the so-called break thrust.' This break, at the characteristic > WUlto. BaUey. U.S. GaoL Surr.. 13th Ana. Rcpt., tWl-91. p. 22S. 00 ffi^jenA fSastini^ UO14BUUOJ tputSmot) SUOI4WUUOJ »/oue iSossitsiu T**,\f,\, «> *ii 5 r 61 angle of fracture (presumably about 40 degrees), was pro^ubly of great displacement, and relieved the strain for that time, but '.^♦ir stresses accumulated until the member broke again. A third great break seems to have brought the Mississagi quartzite, at the base of the Bruce series, into contact with the top of the Gowganda formation. At that stage the strength of the member wouM be so increased, due both to shortening and to thickening, that movement along the bedding planes will be effected more easily than shear across the formations. The accumulated stress appears to have been so great that the terrane finally closed up like an outspread pack of cards, and rode over the underlying metamorphosed basement along a low-angled fault plane. This movement accompanied a general steepening of the dips of the bedding, and thereby caused very great intraformational shearing. FIELD DATA. Overtkrust Faults. It is believed that the quartzite ridge which stretches from the high hill just south of Espanola station, on the Canadian Pacific railway, to the north boundary of the area, near the line between Baldwin and Nairn townships, and farther to an unknown distance, is thrust over upon the pre-Huronian sediments as an outlier. There are several reasons for this belief. On the south side of the quartzite ridge, 20 chains west from the Algoma Eastern railway, along the trunk road, about one- quarter mile north-northeast of Espanola Mills, there is a fault plane, apparently dipping northward at a low angle, beneath the younger quartzite and above the greatly metamorphosed pre-Huronian sediments. The pre-Huronian quartzites and slates outcrop on the lower land to the southwest of this high quartzite ridge. Aga'n, 30 chains north of t' is fault, on the other side of the high hill, there are pre-Huronian schists. Then in concession I, Baldwin township, on the line between lots 2 and 3, there is a fault between the younger quartzite and the pre-Huronian schists and greenstones, and the fault plane appears to dip at a low angle towards the south; this fault outcrop is on the north side of the ridge. Thus there is a high ridge of quartzite (Mississagi quartzite, described on page 25), bounded on the north, west, and southwest sides by pre- Huronian rocks ; the bedding of the quartzite seems to be in a vertical position, wl :!!La.s Ue bedding of the underlying rocks is indeterminable; and actual i uilt contacts have been found on both the south and north sides of the qiiaruite ridge. For these reasons the quartzite ridge is interpreted as an outlier of the Bruce series, which has been thrust over upon the pre-Huronian rocks in a great overthrust terrane having a width along the fault plane of over 20 miles. 62 Minor Faults. A normal fault between the Bruce conglomerate and the overlying limestone and greywacke formations is not hard to trace beotuse of the mark.xl lithological differences of the rocks involved Its stratigraphic throw is nowhere more than 400 feet, if the younger formations faulted against the conglomerate have been correlated correctly Near the line between concessions III and IV, west of Gnffin and Apsey lakes, the fault appears to have branched into several members, and to have been cut by another fault with a northwesterly bearing. Near Merritt station, showing along the railway and on the southwest shore of Loon lake, another normal fault, which was traced for 3 miles, forks into at least two branches. It lies south of the two thrust faults which cause repetition of the Huronian formations, and which are described in the following section. In the northeast part of Foster township the Bruce conglomerate has been offset almost a mile by a fault at right angles to the general strike of the rocks. This fault may be a thrust fault in almost vertical position, caused by the difference in horizontal displacement of different |»rts of the terrane involved in the great overthrust fault. It is plain that the terrane has been displaced in the neighbourhood of Brazil lake 2 miles farther north than it has been displaced either east of lake Augusta or west of Merritt township. This can be seen easily if a line is drawn across the accompanying map from the base of the most north- erly outcrop of Bruce conglomerate, near the west boundary of Merritt township, to the corresponding outcrop at the northeast end of lake Augusta. The Bruce conglomerate lying between these two points is from 1 to 2 miles north of the line joining the points, and at each end of the line there are notable faults offsetting the central terrane towards the north. These transverse faults and the two normal faults are iiter- preted as relatively superficial phenomena, incidental to the major thrust faults now to be described. Thrust Faults. In addition to the overthrust fault, there are three thrust faults of gr-at throw, whose original angles of rupture are unknown. Although the fault outcrops are hard to trace, the faults have caused repetitions of the Huronian series which are plain. The most northern fault seems to le in a direction almost due east and west, nearly parallel to the strike of the highly tilted quartzites. It is hard to find, because it is between steeply dipping quartzites, much sheared parallel to the bedding and very similar lithologically. The fault breccia has been seen on the e.ist shore of Apsey lake, due cast of the liiile island south of the narrows and on the south side of a diabase ridge 1 J miles west of the same island • 63 a fault in lot 8 on the louth boundary of Hallam township ia thought to be the continuation of the same fault. It is supposed that the fault passes between the quartzite hills in Hallam township, and that it lies beneath the sand-plain. A mile east of the outcrop of conglomerate on Apsey lake there is a little lake, near the south shore of which there is the continuation of the same fault. From there eastward it h is not been traced. It is thought that it passes to the north of the large point on the west shore of Loon lake, and it appears in lot 5, concessbn IV, Foster township. A fault zone continues northeastward from that place passing between lakes Augusta and Panache, and crossing the eastern boundary of Foster township. By this means Bruce conglomerate and the Espanola formations are brought close to Gowganda conglomerate on the north side, and to Mississagi quartzite faulted against them on the south side. There is another fault less well exposed. A small outcrop of coil- glomerate on the southwest shore of Apsey lake drew attention to a fault between the quartzite and the conglomerate north of it. (See also pages 29 and 30.) The quartzite is so nearly vertical in position and so much sheared, that the fault would not have been discovered if the conglomerate had not been there. Westward the conglomerate is cut out within 200 feet of the lake, and the fault line could not be traced farther. But on the south side of a quartzite hill one-half mile west of the eastern boundary of Hallam township, and a little to the east of the boundary, there are other fault outcrops, almost surely part of the same thrust fault. Westward it probably intersects the other thrust fault just described. Eastward from Apsey lake the fault is supposed to pass across a swamp on the east side of the south bay. It could not be found in any of the rock outcrops around the swamp. What is taken to be a continuation of the same fault is on the south shore of the larger point on the west side of Loon lake, and it appears to continue eastward to where it is cut off by the third great fault now to be described. Cutting off the fault just described, in the southeast comer of Foster township, there is a fault of very great throw. The fault outcrop runs from the southern boundary of Foster township, nearly on the line between lots 9 and 10, in a nort2ieasterly direction into the most westerly bay of lake Panache. This fault has brought the lower part of the Mississagi quartzite into contact with the top of the Gowganda formation. Although the outcrop of none of these great faults has been traced continuously across the area, the distribution of the rock formations requires their presence. In the structure sections on the map which accom- panies this report, the sequence and repetition of the formations and the faults are shown diagrammatically. It is difficult to correlate and to dis- tinguish formations so similar as the Mississ^i and the Serpent quart- iif 64 MECHANICS OF THE POSTULATED MOVEMENTS. acter^r:^°T*'r.*^P"^ ^"^^^ °" *^«* '«t°"^ *»»« char- Character of the Stresses. All stresses may be resolved into the two claasea, shearing stK«i and compressive .tress including its negative oh^Lli^f Physical Nature of the Members Invoked plasUc bodies are m quite a different class anH ti,«:, k-u • . stress is markedly different fromS otSdlL^^ "^^^7 Tt' .t flo^ S;'l "".l'° '*" deformability; typically it does noTrupt^e ^ri« r'" i T *^°5'^« there is perfect transition. ' series of rock formations are characteristically hetero«neo..«- they are composed of both plastic and rigid rock of readilv fnW^i and of massive, unyielding members. B^t iZ^^'te «"£ hltf "T* terranes which have been deformed show/by 41 naS^^f S^^r^' both. For example a clay formation may contain many disseminated ng|d quartz grains, but the formation as a whole is plastTc^Sv^r^; « Leitk. C. K.. "SuuaunI ceoloar." I9U. p. 16. the same clay formation may be encloMd above and below by thick, rigid qurn/Ue members, and the whole terrane may be one of great competence. Thus, many terranes which contain very plastic layers are rigid entities, and mixed members are either rigid or plastic bodies according to the distribution and proportion of their oonstituena. In general, rocks are peculiar in being relatively weak in resisting tension, but they are strong under compression. Shape of the Members. Compression, as we consider it for unsupported, homogeneous, rigid bodies, is relieved in many ways which depend on the shape of the members deformed. This seems to be a consideration neglected by geologists, probably because the original shape of the deformed members is generally indeterminable. Willis' has pointed out the importance of the original attitude of the formations deformed, and the influence of initial dips. In many cases the attitude of the formation results from thrust forces which have deformed the formations. Going back to the cause of that particular attitude, in a general case we muct consider the original shape as well as the original dips of the formatbn affected. Among engineers it is a matter of common knowledge that the effect of thrust is different upon short blocks, long columns, plates, and irregular masses. It is also recognized that the shape of the end of a column influences the nature of its flexure and its breaking strength. The shape of the end of the member determines where the member will start to bend under thrust. It is well known that a long column is more flexible than a short one. It is easy to bend a long steel rod, but it is hard to bend even a thin one if it is short. The effect of flat ends (also known as flat bases, square ends, and fixed ends) on a column is to shorten that part of the column which bends (Figure 5a) ; with round ends, the column bends from end to end, having the greatest flexibility of all colunms of equal dimensions (Figure 5b). If a column has roimd ends which are clamped before flexure in such a way that the column cannot turn about its axis, nor yield in any way at its ends, its strength becomes that of a column with fixed ends, because the whole length of the column does not take part in the bending. Any fixed end, whatever its shape, gives a rigidity to the member greater than that given by a round, revolving end. The strength of a column with one square or fixed end and one round end lies between that of the two types (Figure 5c). A column with two fixed ends is four times as strong as a similar column with round ends, and nearly twice as strong as a column with one fixed end, and one end rounded but so held that it can yield only in one direction (technically known as a pin-and-square end). > Winii. laUtf . UA GwL Snrv., IJth Au. lUpt.. pt. 2. 189I.M, p. 2«. 66 (a). WitkhMwdara^yorm 0nd$ ft). With round«d and (c). ^•t*'on»flM«dmdandooerour, Except for the caw o( ao ncJchty aa overburden that incipient relief by flexure is not poMible, wlien tile weskenim due to flexure doet not ocrur, and the ptrenith of tlie cdunm foroi «ppma fh>« that of a •hort block. ■ The behaviour of a plate la moat like that of a pin-and-aquarc ended coluaa. • Collina, W. H., Geol. Surr.. Caa.. Mua. BulL 22. 1916. p. 6. 68 Suipfoj »»4/jo uoiSmy •jnjdiu JO uoiStu ^- • 5' I Ji "S .9 h. «9 the Huronian series in La Cloche mountains, and on account of the massive character of the pre-Huronian rocks north of Espanola, the region be- tween La Cloche mountains and the pre-Huronian rocks to the north may have been a structural unit within a greater one. Therefore, there is justification for discussing the deformation of Espanola terrane without further reference to the diastrophism of these other areas. In the Bruce series there are 700 feet of greywackes and limestones, very incompetent formations, which are much crumpled and folded. There are thick massive quartzite members, thousands of feet thick, above and below the deformable formations. Above the upper Bruce quart- zite lies 600 feet of Cobalt conglomerate, which is a competent formation overlain by incompetent slate, which, in turn, is overlain by massive conglomerate and thousands of feet of quartzite. The greywackes between the quartzites, and the slate within the conglomerates, fortified by their rigid neighbours, seem to have had little influence on the whole, which was a rigid compilation. It is assumed that the Bruce and Cobalt series, like most sedi- mentary deposits, had lenticular shapes, and that the younger was deposited upon the other in such a way that together they formed a lens-shaped whole. Although they are anomalous in their conglomerate formations, for the most part, they were laid down as coarse arenaceous elastics near the land, progressively growing first thicker, and then thinner and more argillaceous towards the deep parts of the basin of deposition. Thus, there were competent formations near the land on the north side, and incompetent rocks at the other side far to the south (Figure 7). Upon subjection to compression, bending started somewhere about the middle of the member, probably nearer the south end than the north end, and the pelitic, pliable materiak folded into and around the end of the quartzite formations, and made in effect a round end to the member; but this must have been far south of La Cloche mountains. The land- ward side, in Espanola area, was probably held rigidly by strong abut- ments, chiefly the pre-Huronian schists fortified by pre-Huronian granite masses. Thus, bending started near the free end in Espanola area, and the whole local member assumed the warped form indicated in Figure 8. Being a competent and rigid compilation, the terrane broke at the step fold.' The stratigraphic throw of the fault may have been as much as 7,000 feet. On the assumptions that the beds were horizontal, and that they ruptured at an angle of 40 degrees to the horizontal, the displacement along the fault plane would amount to about 10,900 feet, • WUUi. BiHn. U.S. Gcol. Surr.. IJth Ann. Kept., IS9I-92. p. 2U. 70 t4i*od»p anf/ty I I (i CQ & I 71 and the horizontal movement to about 8,400 feet. Thu«. the fault would cause a surficial shortening of about IJ mile«, which requires that the whole maf^ on the upthrust side of the fault, to an unknown depth, moved bodily a long way, probably shearing over the old pre- Huronian surface. This carries the assumption that the ancient base- ment was not involved in the transmission of these thrusts, and the assumption is based on the fact that there is an overthrust fault between the Huronian and the pre-Huronian outcrops. According to this the strained member was reduced in length by li miles. It is believed that the terrane had the form of a lenticular plate, and the behaviour of a plate is essentially the same as that of a column.' According to Euler's formula, the strength of a long column, aud, therefore, a long plate also, is proportional to in which E-coeffident of elasticity of the material involved, /-moment of inertia, and L =■ length of column. Therefore, the strength of a long column or plate is inversely proportional to the square of its length. By making such a change that L* in the formula is altered to (L- IJ miles)», the strength of the member is much increased, especially so if L is not very great. L was probably not over 20 miles; thus, the strength of the member at Espanola area was increased by shortening (other factors being neglected) in the ratio of 1 1 20* • 18-5» " • "' which is an increase of 16 per cent. The first break involved four main pieces of work: (1) rupture across the beds; (2) a parting or a flow, permitting the mass to move horizontally forward, to take up the heave of the fault; (3) overcoming the friction of the mass along both the base and the true fault planes; (4) the movement of tijat great mass through the distance of displacement. The first of these was probably the least. The next break occurred in the thickened part of the wedge, and in a shortened member, but the basal zone was weakened so much that it took a smaller force to cause the break in spite of the strength- ening factors. It is assumed that the different shortenings of the same terrane provide a means of comparing the accumulated forces. In the second faulting, the throw was less than one-quarter as gieat as in the first, and, therefore, the force relieved is supposed to have been smaller than the first rupturing stress. The stratigraphic throw of the ■ Church. I. P., "Mechuica of BntliMCTiiif ," 1909, p. 3U. Chuich kppUe* lUakiM't formula to tht bockUas of ■ plate, but RuiUne'i and Bul«r'i formulaa an fuadamentally tbt mum. 72 second fault is estimated at 1,500 feet, and thj horizontal movement at about 1,800 feet. The third reverse fault was greatest. Its stratigraphic throw is between 10,000 and 14,000 feet, resulting in a heave of 2 or 3 miles. A very great stress must have accumulated, and the terrane must have been very strong to have withstood the growing forces which finally ruptured it. The second fault had thickened and shortened the member as the first fault had done before, and in a similar numner the third fault added to the strength of the compressed terrane. Figure 8 shows the postulated relations of these three faults; the earliest fault is marked AA, the second one BB, and the third CC, and the supposed sole is marked AZ. It is possible that the outermost fault followed those farther south, which would be similar to the process obtained experimentally by Cadell.* There is no datum available to prove which of the three faults is the oldest, although it is dear that the most southerly fault followed the one which it cuts in Foster township; but the structure seems to be explained reasonably under the supposition that the outer- most fault was the first to occur. After the third break, the terrane had a weakened base due to the thrust movements, and all the boundaries of the blocks or slices between the three reverse faults were planes of weakness, so that they were in condition to become tilted and rotated under further compression (Figure 8d). At this stage, there was a free sole (AZ) under the greater part of the member. Its strength to resist rupture was still very great, and its most ready relief consisted in the extension of the sole into a great thrust fault. During this fault movement, each formation became more tilted, each of the thrust fault planes was rotated into a higher angle, and the whole mass rode forward along the low-angled shearing plane (Figure 8d, ZZ). The last movement is like that of pushing together an outspread pack of cards, and it involves great intra-formational shearing. Plate VI shows a piece of oak wood which has been compressed at a high angle to the diiection of its grain, and there has been slip between every one of the strong planes in the block; bedding planes of a compressed formation behave in the same way as the grain in the wood. This intra-formational shearing forms essentially an imbricate structure,* only instead of slice faults transverse to the bedding of the formations, there are many shearing planes parallel to the highly dipping bedding. > Cadcn. H. W., "Gcnenl dcKriptkn of the geological itnictuic of the ngkm tflcctcd by poK'^uibtlaa movemcnti In the North-WeM Hlghluxle." Geol. Sunr.. Great Briutn. Mem.. 1907. p. 474. > "Gcncml deecnptlon of the geoiog i ol ■tnictuic of the region affected by poet-Cambciaa ■iiiiiiwin to Um Nofth-Wc« Highludt," Horae. J.. Gwl. Sunr.. Great Britain.. Mem.. 1907, pp. 4«»44. 73 a. * B c (c). Atth0 Km* of ff>0 third fhrust fhult. (d). At th0 hm0 of the o¥mrthrust fkult. DiaplaetmtntoffBulHS unknonn \eaeh •ofical Jurvty, Caimdt Figure 8. Hypothetical atructure of Huronian formations at E«panola. 74 Some of the quartziles show a marked development of schistose bands at subdual spacing, and the ready weathering of these micaceous layers produces the rutted surface mentioned on pages 26 and 27. It is worth suggesting that probably these zones are due not alone to original inequalities in deposition of the quartzitcs, but largely to the localization of shearing strains within the competent formation ; and the mineralogical changes in these micaceous zones are controlled both by impurities localized in the quartzitcs and by the mechanical, equalized distribution of shear within the relatively homogeneous formation. 1^1 Assumptions. (1) Continuation of the overthrust fault under the whole area is assumed. (2) That it lies everywhere between the prc-Huronian base- ment and the Huronian members is an extrapolation of the conditions north of Spanish river, described on page 61. (3) The order of succes- sion of some of the faults as assumed, and the foregoing discussion is based in part upon the hypothesis that the overthrust fault followed in time the three large reverse faults. Careful search for pre-Huronian fragments in the fault breccia was made in the hojie of finding whether the older rocks were involved in the displacement. Nothing was found to show that they were involved, but that is negative evidence and the case IS not proved. The fault displacements are estimated upon the apparent present thickness of the formations, which may not be the same as before deformation, and upon an assumed awrage angle of rupture which may be erroneous. The computed horizontal shortening along the three main reverse faults amounts to 4 or S miles. The dis- placement of the overthrust fault is not known, although in some places the displacement appears to be 2 miles farther than in other places, nor is there any measurement of the movement along the bedding planes. According to these considerations, the total horizontal movement appears to have been many miles. (5) The original shape of the Huronian series IS not known; it is a.ssumed to have been normal, but perhaps it was not. (6) As stated on page 72 the assumption that the outermost thrust fault preceded the other two faults may be wrong, but it seems most reasonable. So many assumptions would be unpardonable, were data obtainable; in this case the smallness of the area studied, the drift covering, the' slight relief of the surface, and the metamorphism of the rocks, combine to conceal the facts. It seems Ix-tter to advance a tentative hypothesis, dependent upon assuni[)ti.)n.s as it is, than to leave an intcre.sting problem with no solution attempted. 7S Fads in Conclusion. Irrespective of assumptions, some conclusions are justified. The Huronian rocks at Espanoia were strained by great compressive forces which shortened the terrane in a north-northwest direction. The resultant movements have five main effects: (1) The forma'ions are in a steeply tilted position. (2) The rocks have suffered great miner- alogical and textural alterations. The quartzites are sheared and seri- citized, the greywackes are folded and changed to slaty rock, the con- glomerates are sheared and chloritized, and the limestones are squeezed and crumpled into marble. (3) There was great intra-formational shear- ing along numerous, sub-equally spaced planes parallel to the bedding. (4) The Bruce series is thrust upon the pre-Huronian basement along an overthrust fault plane, at least as regards the outcrops between the Algoma Eastern and the Canadian Pacific railways. (5) There is repetition of parts of all the members of the Bruce series. m;.. 4i^^ !••: --^-.^i.!-" ■ v« t-. A ■ ^ •::' ..1. >1^>r:- 77 Platk I. „?v_ A. Skyline from a hill near \Vel>l)WO(«l, lcc.ii!'. .ii HiiT on the sli.ire nf MiMin lake near the outlet. The rlitT faiv- xiiiihwaiil. U'age 16). 79 IYatk II. ilJi^ii^ mMHtmA ll f W'"' fW^ • ^ -^ r . ^- i^Vi # >' \~'l ■ ■^•:^c^^ ^ ^^ / ^:i> '» . - " '*- A. Typiral outcrop of Hruce limentonconitKnorthwi-itt shore of lirazil lake. (l'aKe34). U. S Lamination of the quartzit: Lawson, A. C Liesegang, R. F Limestone, Espanola Location Long Lake mine Loon lake Low. A. P Lumberinf; 43. 67 40 22.25 57 36 1 52 30,41 17 3 91 I MacUnnon tp . Marlelcor Marihall, John R Martin, l^wrence May lake McCabe lake Mechanic* of the poatuUted movemente . Merritt . •tation 33, 38, tp 3, Metamorphiam " contact Mica phenocryitt Miller, W. G MiMissagi quartiite * ieriea Moon lake M M I 10 67 67 64 I. 4 40, 41 13, 23 13 SI 20 S 3S S 16 1^- Olivine diabaae Onondagan epoch Palisade* of Tendinciida lake Panache lake 3, Peneplain Permian Squantum tilllt* .... Phyllite Physiography Pigeon point, Minnesota Pleistocene 6, Porphjrrite, gabbro Post -Glacial Potsdam Pre-Huronian Pre-Huronian sediment* Previous work Proterozoic Pulp mills SI 9 16 27 10 4« 20 9 S4 S5 51 i$ 10 S9 19 3 10 3 Quartz diabase Quartzite " Serpent . Quaternary SO 13. 13, 16 3« 5S Richters, F . . . Ripple-marks. Rose tp 57 56 13 S. St. Leonard lake 40. ♦! Salisbur>;, R. D 1, H Sand-plain 55 Sands, lake 6, 55 Saugeen beds 56 Sayles, R. W 48 Schist, greywacke. " micaceous • quartzitic * staurolite Schucbert, C'has Sediments, Pre-Huronian . 20 20 21 20 10 19 h M n Pags Serpent quartsite i- «:?'5? Shakespeue tp ^' ^' ?i ^urian JO Slate conglomerate «3 • • Bruce Mine* 33 " Gowganda jJJ " micaceous 20 Solution holes ViA,, il Spanish river 3, TO, 55, 50 " River Pulp and Paper mills 3 Spheroidal weathering 4* Stratigraphy 19 Stratton lake ^'' 2T Stresses, character of *♦ Structure 59 Sudbury *J Syenite *3 T. Table of formatbns ^$ Tabs 15 Temiskamian 5 Tendinenda lake \° Tertiary »» Till 6 Tillite, Pre-Cambrian *» Timiskaming, lal;i S* Todd, E. W. 1 Topography * Transportation ■ ■ _^ ,' Tulloch lake 5, 29, 38 Tynell, J. B 17 U. Uuconformities ' V. Valley 13 Van Hise, Chaa 10 Vermilion river 3, 30 W. Webbwood 3 • station fW Weidman. S ,,10 Whiskey lake 22, 24 Willis, Bailey .„ « Wilson, A. W. G Ik }2'\i Wilson, M. E 10, 48, 57 lii 11. ■' wm '.^ LEGEND I IKCWUNAWAN < IViatocaw aadBjecmtt ■mimaitarammutta atlftmaMlt Jrtnj Dudtaat (mt^a&iv* mini fiaiiMiti