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Kewagama Lake Map-Area Quebec Uw- -^'- 1 i «!■.: M m 'i\ % ^1 "^5 lip « 1" '' ^^^ 11 P PBIr? ,J*i:»J4 CANADA DEPARTMENT OF MINES Ho«. Uvu CoMH. Mnann, A P. Low. Dipctt 1Iii(utm, GEOLOGICAL SURVEY R. W. Bmki. Uiuctm. I MEMOIR 39 I No. SS, OaOUHMCAL 9CBIM Kewagama Lake Map-Area Quebec ■T M. E. WUson Ottawa OoTiBKUim PBiirnNo Bvsiaq 1913 No. IHM 0^ .»* CONTENTS. CHAPTER I. 0«Mt^MktamMt>Ml ukMrnMrnMU Pr*vleMwgrk B»o"n by scow and launch on the BUok river At end. „ lU. View lookinc eastward from the Swinging hills. . . " IV. View lookiiut westward from the Swinging hills, Mount Shiminis !! ,X" j!f^"„^''™'y "^ t*>e Abijevis hills from kamak hill " VI. The Swinging hills from Lake Opasatika " Vn. Rapid on the La Sarre river « " Vin. The Okikodoaik, a typical river of the clay belt . .. 'X. Photomicrograph showing eutaxitie structure in basalt.. " X. Ellipeoidal structure in the Abitibi volcanics. . " XI. Bun structure in the Abitibi volcanics " .^I. Irre^larlpr weathered surface of Abitibi volcanics " vK* 5"^*'«","' glaciated surface of the Abitibi volcanics . . ' ' " |_ Yir' n?™' • '''"'"'*® ""I carbonate in chloritic rock " XV. Photomicrograph of tourmaline in quartz from veinlet traversing ferruginous dolomite " tAXI" ^otomiciograph of the greywacke of the Pontiac series " XVII. Photonaiorograph of the greywacke matrix of the conglomerate of the Pontuui series " " AJIU- P'»°*omicn^pTiph of the Pontiac schist " vv 5^*"° ■"'^.* dipping steeply towards the north XX. Fragments of the Abitibi volcanics included in granite of Bobertson Lake bnthoUth .'." i?^' *''*?«'^*«' breccia formed by the breaking up of a granite dyke " XXn. Photomicrograph of the matrix of the basal conglomerate of the Cobalt series. Ordinary light " XXin. Photomicro^ph of the matrix of the basal conglomerate of . v-vm r^t Cobalt series. Crossed nicola •■ '.. ■^^SX" S'^H'M surface sloping towards the north, Lake Dufault XXV. Btratined post-glacial clay •• !! .^^Xl' S.*™**^®"* ""•'^'■'''■l clay, near view. ..... . ! " XXVII. Concretions from clay ■■ " XXVIII. A: Surface of quarts on margin of veinlet in ferrujhnoiis dolo- « -wirr-v T»_°"*®' Inclusion of dolomitic rork in quarts " XXIX. Property of the Union Abitibi Mimnji Company " Fia. 1. Index map showing position of area 4 •• 2. Island in La Sure river formed by the Uteral diversion of its trib^ _ utary, the South river yj 1; 3. Linear valleys of the region which are unrelated to rock structure 19 4. A generalised logical section of the rocks occurring in the Timis- kaming region 32 5. Camera luclda drawing of amphibolite occurring on Happy Out- look point, Lake Opasatika go 6. Section through kame occurring on the National Transcontinentai , „ nul'ray. La Sarre township. Que 103 7. atnke ol quarts veinlets and veins in ferruginous dolomite, occiir- nng north of the Cascade rapids on the Kinojevis river, Manne- viUe township j.i 8. Strike of quarts veinlets in ferruginous diiomite, occurring to the north of Larder lake, McGarry township, Nipissing district, "D* 112 " 9. Strike of quarts veins shown on map of lots 10 and 11, concision II lisdale township, in the Porcupine gold area U3 THE KEWAGAMA LAKE MAP AREA, QUEBEC. CHAPTER I. INTRODUCTION. GENERAL STATEMENT AND ACKNOWLEDGMENTS. The following report is an account of tiie geology and economic possibilities of a region in northwestern Quebec, lying immediately east of the Ontario boundary and south of the Na- tional Transcontinental railway. This district was known, in a general way, to be geologically somewhat similar to the adjoining portions of Ontario, but little detailed information was available with regard to either the character of the country, its geology, or its econoniic possibilities. It was further apparent that, owing to its proximity to regions in Ontario where gold had been recent- ly discovered and the easy access afforded by the National Trans- continental railway, the district would soon be actively pros- pected. It was, therefore, deemed advisable that the geological examination of the district be undertaken. Throughout a considerable part of this region, rock exposures are not abundant, and with a limited amount of time available for the work, it was not possible to carry on the detailed investi- gation which the complicated geology of ancient Pre-Cambrian rocks demands; for this reason the report must be considered as preliminary in character, presenting the broader geological features as observed in scattered outcrops, supplemented by more extended observations on some of the rocky hills and ridges, which occur here and there throughout the region. The report is accompanied by a geological map on the scale of 4 miles to 1 inch. This, however, includes the area to the south and east of the Kinojevis river examined by Dr. J. A. Bancroft', as well as some of the observations of Mr. W. J. Wilson along the line of the National Transcontinental railway, the Harricanaw river, and La Motte (Seals Home) lake ». Many of the lakes and rivers of the region had not been pre- viously surveyed, so that a considerable art of the time spent in ' Min. Op. in Prov. of Que., pp. 160-207. ' Geological ReoonoaiMsnoe along the line of the National Tnuueontinenta railway u Weateni Quebec, Memoir No. 4. Geo. Surv., Dept. of Mines, Can 1910 1 2 field work was devoted to the preparation of the topographical map. For this purpose, the Rochon micrometer telescope and surveyor's compass were employed in surveying ths navigable waterways, while the chain and surveyor's compass were used on the portages. The larger inland lakes were located by chain surveys, but many of the small ponds were simply sketched and tied to the main traverse routes by paced lines. As the region included on the map is intersected by numerous base, meridian, and township lines surveyed by the Provincial Crown Lands department, and is limited on the west by the interprovincial boundary line, the surveys made, as outlined above, were checked at numerous points, so that a tolerably accurate map was obtained, upon which the areal extent of the various geological series could be delimited. In addition to the traverses made by the writer and his assist- ants, the following surveys were used in the preparation of the geological map. Survey of Lake Dasserat by Lindsay Russel, 1868. Interprovincial boundary survey between Ontario and Quebec from Lake Timiskaming to the height of land by O'Hanlv and O'Dwyer, 1873-74. Survey of the eastern part of Kekeko lake, Kinojevis lake, the southern part of the Kinojevis river, and Lake Dufresnoy by John Bignell, 1893. Survey of Makamik lake, Lois lake, and the Lois river by J. F. E. Johnston, 1901. Survey of the northwest shore of Labyrinth lake by W. J. Wilibon, 1901. Extension of the Interprovincial boundary survey northward from height of land by Patten and Laberge, 1906. Survey of the lower part of the Bellefeuille river, part of the Harricanaw river, and La Motte lake by W. J. Wilson, 1906. Survey of the upper Ottawa, De Montigny lake, the Asko- wish river, and Pich6 lake by H. O'Sullivan, 1908. Base, meridian, and township lines surveyed by the Crown Lands Department of Quebec. The present report represents the results of field-work carried on during the seasons of 1910 and 1911. Operations were commenced in the vicinity of Lake Abitibi in 1910, and continued eastward and southward across the St. Lawrence- Hudson Bay divide to the Kinojevis river and Kekeko lake in 1911. The month of September, in both years, was spent in an examination of the country in the vicinity of the National Transcontinental railway to supplement the earlier work of Mr. W. J. Wilson. I was assisted in the field in 1910 by Messrs. N. B. Davis, L. E. Dagenais, J. S. Stewart, and A. C. Simpson, and in 1911 by / 3 Messrs. E. M. Burwash, L. E. Dagenais, J. S. Stewart, and C. P. Sills. Thanks are due to the officials of the National Transcon- tinental Railway engineering staff, to the employeesof the Walsh Transportation Company, to the officers of the Hudson's Bay Company and of Revillon Freres, to Mr. Chas. Richmond, and to many others who contributed by their co-operation to the progress of the work. My grateful acknowledgments are also due to Dr. Joseph Barren, Dr. Isaiah Bowman, Dr. J. D. Irving, and Dr. L. V. Pirsson, of the Geological Department of Yale University, and to Dr. C. K. Leith, Professor of Geology in the University of Wisconsin, for many suggestions and criticisms embodied in the following pages, and also to Mr. Stewart J. Lloyd, Assistant Pro- fessor of Chemistry and Metallurgy in the University of Alabama, for the chemical analyses on pages 47, 48, and 50. LOCATION AND AREA. The region described lies in northwestern Quebec adjacent to the Ontario boundary and south of the National Transcon- tinental railway. The map which accompanies the report extends from the interprovincial boundary to La Motte lake and the Harricanaw river and from the National Transcontinental railway to O'Sullivan's base line, or expressed geographically, from longitude 79° 30' 66" to longitude 78°, and from latitude 48° 50' to latitude 47° 45'. The position of the sheet with respect to the adjacent regions is indicated in the index man. Fig. 1. TRANSPORTATION AND COMMUNICATION. Until recent years, the usual means of access to this region was by canoe from Lac des Quinze, but with the construction of the Timiskaming and Northern Ontario, and National Trans- continental railways, alternative routes have become available. These are especially advantageous in reaching the northern parts of the district, the canoe routes from the south still affording the easiest means of communication for the more southerly areas. Since the National Transcontinental railway crosses the northern part of the sheet, this portion of the region is now easily reached by train from Cochrane, Ontario — tb^ i'lnction point of the Timiskaming and Northern Ontario, ,v e Na- tional Transcontinental railways. The districts at btance Fio. 1. Index map showing position ot area. from the railway may be reached by canoe along the numerous waterways in its vicinity, the particular route to be taken depending on the destination desired. For the western part of the sheet, the La Sarre river affords an uninterrupted waterway to Lake Abitibi, from which the Abitibi-Timiskaming canoe route may be followed southward. The Kinojevis river can also be reached from the La Sarre by way of Lake Abitibi and a canoe route which leads across the height of land from the eastero extremity of Lake Agotawekami through Kakameonan and Dufresnoy lakes. This route, however, requires considerable portaging and follows small streams, the headwaters of which become impassable in time of drought. After the construction of the Timiskaming and Northern Ontario railway to Matheson, Ontario, a common means of access to Lake Abitibi was by canoe from that point along the Black and Abitibi rivers, A number of launches and steamboats were maintained on this route by the Walsh Transportation Company during the summers of 1908, 1909, and the eariy part of 1910, but were withdrawn as soon as the construction of the National Transcontinental railway to Lake Abitibi rendered them unnecessary. At the eastern border of the map, there is another line of communication transverse to the National Transcontinental railway, along the Harricanaw river which is navigable without interruption as far south as La Motte lake. Between the Harncanaw and the La Sarre (Whitefish), the streams lie adjace.'^t to the height of land and are consequently small. The Villemontel and Kewagama rivers, however, afford a tolerably good canoe route from the outlet of Fork creek— a point within a half mile of the railway— to Kewagama lake. The Villemontel meanders greatly and is interrupted by a number of rapids and a log jam, but the portages are short and the rapids can all be run when the water is high. Another canoe route has recently been cut out leading from the southeast comer of Lois lake to a series of lakes which occupy a north-south gorge-like valley in the Abijevis hills, and thence to Horsetail lake and the Kinojevis river. This route IS, however, very rough and requires over 4 miles of portaging and for this reason is not commonly used. The usual means of communication for the southern part of this region is by canoe through some of the waterways tributary to Lac des Quinze. There are two roa 's which may be followed i^mP i"?^^ Timiskaming to Lac des Qi ze, one which leads from Ville Mane to Gillies farm at the sou end of Lac des Quinse and the other, from North Timiskaming to Klock's farm 15 miles farther north on the same lake. The country adjacent to the Kinojevis river may be reached from Lac des Quinze either by way of the upper Ottawa and Lake Expanse, through Roger and Caron, or through Barriere, Albee, and Kekeko lakes. The region in the vicinity of Lake Opasatika is easily accessible from Lac des Quinse along the Abitibi canoe route of which Opasatika forms a part; but it can also be reached from the Timiskaming and Northern Ontario railway by road from Dane to Larder lake and thence by the canoe route which leads from Larder through Raven lake to Opasatika. HISTORY. GENERAL HISTORY The earliest explorations in the region were those of the French who penetrated the northern wilderness of eastern Canada in quest of furs. From the days of the coureur du boia until recent years, however, the district has remained a wilderness practically unknown except to the Indian, the fur trader, and the missionary. The extension of lumbering operations to the upper Ottawa about 40 years ago, resulted in considerable activity in the southern part of the region for a time, but these opeiations had largely ceased when interest in the region was again revived by the construction of the National Transcon- tinental railway. The discovery of the silver-bearing veins at Cobalt in 1903 was followed by much prospecting activity in adjacent regions, to which a further impetus was given by the discovery of gold bearing quarts veins at Porcupine in 1909. Following the Cobalt discovery, a number of prospectors visited this region and in July 1906, Messrs. Alphonse Oilier and Auguste Renauld made a discovery of gold in a veinlet of quartz and dolomite which intersected a porphyry dyke, occurring on the south shore of Fortune lake, about 2 miles northeast of the north end of Lake Opasatika. The claim staked by Oilier and Renauld was taken over by the Pontiac and Abitibi Mining Company and later by the Union Abitibi Mining Company. Operations were commenced on this property in 1907, but no progress was made until the past year when active development work was begun. In the summer of 1901, Mr. J.F.E. Johnston in making a geological reconnaissance for the Geological Survey in this region, noted the occurrence of molybdenite in a quartz vein cutting the granite which outcrops on the peninsula in Kewagama lake. In 1907, Mr. C. H. Richmond discovered molybdenite in pegmatite occurring on the Kewagama river, and since that time, this mineral has been found to be of wide occurrence in pegmatite dykes and quartz veins associated with the granite Qi ''''%^j^w^imise?'£^:^iii^T,i*i.:L^>ii^j.7^i,,^,^ of that vicinity. Nearly all of these occurrences are held by mining companies some of which have commenced operations for the purpMDse of attempting their exploitation. The two localities mentioned, the Union Abitihi Company's claim to the northeast of Lake Opasatiica and the molybdenite occurrences in the neighbourhood of Kewagama lake, are the only places in the region where work is, at present, being carried on. The development work on all of the other claims consists merely of stripping or test pits a few feet deep. PREVIOUS WORK. The earliest geological work in this region was a report by Mr. Walter McOuat on the "Country between Lake Timis- kaming and Abitibi", which was published in the Report of Progress of the Canadian Geological Survey for 1872. This consisted of a fairly detailed account of the lithology of the Tiraiskaming-Abitibi canoe route and of the shores of Lake Abitibi. In 1901, Mr. J. F. E. Johnston made a reconnaissance examination of the geology along some of the waterways of the region. These included the La Sarre river, Makamik lake, Lois lake, the Lois river, the canoe route from Lake Duparquet to Dufresnoy lake, and *lie Kinojevis river. Mr. Johnston's observations were published in the Summary Report of the Canadian Geological Survey for }001. In 1904, Dr. W. A. Parks made a geological examination of the rocks along some of the canoe routes in the country north of Lake Timiskaming, including the southern part of the Timiskaming-Abitibi canoe route, Dasserat and Laby- rinth lakes. His report was published in the Summary Report of the Canadian Geological Survey for that year. During the summer of 1906, Mr. W. J. Wilson investigated the geology along the waterways and railway survey lines adjacent to the National Transcontinental railway. "This included the examination of the rocks along the Fly, Belle- feuille, Villemontel, and Harricanaw rivers and along the shores of La Motte and Kewagama lakes. The results of Mr. Wilson's work were published in me Summary Report of the Canadian Geological Survey for 1906, and again in greater detail in Memoir No. 4: A Geological Reconnaissance along the line of the National Transcontinental Railway in Western Quebec. Geological Survey, Department of Mines, Canada, 1911. The reports of the Provincial Department of Mines for Quebec for the years 1906 and 1907 contain accounts of recon- naissance trips through this region made during the summers of those years by Mr. J. Obalski. BIBLIOGRAPHY. Walter MeOuat. J.F.E. Johnston.. W. A. Parks. W.J.Wilson. .Report on an •xamination of the countnr between Lake Timiskaming and Abitibl. Report of Progress, Geological Survey of Canada, pp. 112-135, 1872-73. . Eastern part of the Abitibi region. Summary Report on the operations of the Geological Survey of Canada, pp. 130-143, 1901. .The geology of a district from Lake Timiskaming northward. Summary Report of the Geological Survey of Canada, pp. 108-225, 1004. . . On explorations along the proposed line of the Transcontinental railway from Lake Abitibi eastward. Summary Report of the Geological Survey, Department of Mines, Canada, pp. 110-123, 1006. J. Obalski Explorations on the north of the county of Pontiac. Mining operations in the Province of Quebec, pp. 6-27, 1006. Explorations north of Pontiac. Mining operations in the Province of Quebec, pp. 42-56, 1007. M. E. Wilson Northwestern Quebec adjacent to the Interprovincial Boundary and the National Transcontinental railway. Summary Re- port of the Geological Survey, Department of Mines, Canada, pp. 203-207, 1910. V.J. Wilson. M. E. Vilson. .Geological reconnaissance along the line of the National Transcontinental railway in western Quebec. Memoir No. 4. Geological Survey, Department of Mines, Canada, 1910. . Kewagama Lake map area, Pontiac county, Quebec. Summary Report, Geol. Survey, Dept. of Mines, Canada, pp. 273-279, 1911. CHAPTER II. SUMMARY AND GONCLUSIONS. TOPOGRAPHY. Thetr "raphy of the AbUibi district exhibits the typical low rehef i.ud youthful drainage syatema wl \:h are generally charactenstic of the Laurentian plateau, but local modifica- tions in these features have been brought about by the deposition of stratified clay and sand frona a huge lake which covered a large part of the region for a period of about 260 years following the retreat of the last Labradorian ice sheet. ^ At the beginning of its known physiographic history this region possessed a mountainous topography, but early in the Pre-Cambrian era a most prolonged period of denudation occur during which the surface of the region was reduced to a peneplam. Upon this ancient erosion surface an assemblage of clastic sedi- ment8--t»'p Cobalt series— was laid down. These rocks were later flexed and intruded by the Nipissing diabase and syenite porphyry, after which denudation again began in the region and continued until the Palsosoic when the region was submerged beneath the sea and Silurian sediments deposited. Since the retreat of the Palsosoic sea l his region has suffered no orogenlc disturbances, and, as far as known, has always been a positive element in the earth'b crust, but has possessed such a low relief throughout all this interval that the progress of deaudation has been exceedingly slow. Much of the erosion accomplished consisted in the stripping away of sediments, so that the present topography corresponds very closely in places to one or other of the ancient erosion surfaces upon which the sediments were deposited. It is unknown whether the Cretaceous peneplain described in other parts of eastern North America, extended over this region or not, but, if such a plain was formed, it was developed, in part at least, on the surface of Silurian sediments which have since been eroded away. The final stages in the physiographic development of the distnct are closely related to the Lubradoran ice sheets which, (1) by denudation and (2) by deposition, imposed a youthfui drainage system on a surface of low relief, thus producing the peculiar glacial physiography so typical of the Laurentian plateau. 10 OENERAL GEOLOGY. The rock! of the AbitlW dUtrict in.v be clswlM both .r«fiKUM to •tructure and age Into three main claMUii : ( I ) the older JSSSS^frthrcXlt -^-»d»^« ««'-"•''"' '"*""'^"' ''' X'S'SX-"' "oS:rc" A'^'*'*'' group are intruded by bathohths and smaller masses of granite and granite-gneiss, these rocks constituting the plutonic subdivision of the older coinplex. rhey art believed to have been intruded during a penod when great orogenic crustal movements folded the « S«/„°f ^JJI *^% oT^*'"'"P'''^ ^^^^ " K''*** synclinorium, ?hi«T.t!^ '^& K l'"r*H,"''"'5 '" **•« '''•Sion described in this report. These bathohths made room for themselves in two ways, (1) by Htmg and thrusting aside the overiying and surrounding rocks, (2) by breaking off and assimilating fragiients of their roofs: (subcrustal stoping). There is ev^ence that the first method was of great importance. Whether the second was an important factor or simply a phenomenon of minor simifi- cauce IS unknown * 1 ^xH 'f";"^ "^ ^l^ 9'*^*'" complex are overiain by a group of almost flat lying clastic sediments-conglomerate, greywacke. argilhte, and arkose-composing the Cobalt series. Where the complete section of these rocks is present there is generally a conglomerate both at the base and at the top, the ireywacke! argilhte, and arkose occurnng as intermediate members. It is showniD the section of the report I . Thich the origin of the Cobalt series is discussed that, the above accession is di. y related to the manner in which the various rocks were laid down, the conglomerates being till sheets deposited from continental facSnetplsits^^^"'^' "''°«^' ^°^ "«^"'*'^ -»-«•--• »..K^-° ^^^ ''IfS'fication of the rocks of the region into major subcLvisiop.. the Kewetnawan intrusives are classed with the Cobalt series. These consist of dykes of diabase and olivine SfnfTv.^*^,„'!.J°^ of syenite porphyry. It is probable that aJI of thrae rocks were denved from the same magma and that they are the equivalent in age, of similar rocks classed as Keween 40591—2 xvcween- 12 awan in the Lake Superior region. In the district described in this report the diabase was observed only as dykes cutting the older complex, but in adjacent districts it occurs both as dykes and sills intruding the Cobalt series. The syenite porphyry was seen in only one locality and in that place occurred as an oblong mass with vertical walls in eruptive contact with the basal conglomerate of the Cobalt series. _ The Pleia+ocene and Recent deposits of the region consist of (1) glacial and fluvioglacial deposits, (2) stratified clay and sand. The glacial material consists of a thin mantle of till scattered over the surface of the Pro-Cambrian rocks described m the preceding paragraphs. The fluvioglacial deposits are more localized, occurring here and there as kames or outwash plains. They differ from the glacial material in being roughly stratified. The second division of the Pleistocene and Recent deposits— the stratified clay and sand— overlies the glacial and fluvioglacial materials. It is believed that these sediments were laid down in a huge lake which covered a large part of the region following the retreat of the last Labradorian ice sheet. ECONOMIC GEOLOGY. There are no producing mines in the region described in this report nor have any ore deposits been discovered which are of commercial value under present conditions of operation. The principal deposits which have attracted attention are the auriferous quartz veins or veinlets and the quartz veins and pegmatite containing molybdenite. Veins of quartz occur in all the rocks of the region, but are most extensively developed in those of the Abitibi group. Many of these veins are several feet wide and extend for several hundred feet, but in no case did assays of a\ crage samples from these occurrences show that a workable body of ore was present. The molybdenite occurring in the region is found in pegma- tite and quartz veins developed in the contact zone of the Pontiac schist and the southern granite batholith. These deposits are all of small extent, however, and are not at aJl comparable with the deposits of this mineral occurring in the vicinity of Kewagama lake. ... ^ ^ * It must not be assumed, however, that the above statement of results has a very important bearing on the future possibi- lities of the district, for the country has not been prospected except in a very superficial way. Geologically the region corresponds very closely to the Porcupine district of Ontario, and with the increaseo transportation facilities now afforded by the National Transcontinental railway is probably one of the most easily accessible and promising prospecting fields in northern Quebec. *J 13 CHAPTER III. GENERAL CHARACTER OF THE DISTRICT. TOPOGRAPHY. GENERAL ACCOUNT. Regional. The region under description belonRs to the irrpnf Pr« Cambrian plateau which occupies nearly the wlml.^^^f It Jt8 details, It possesses a m mutely rueced and vflHoKil.^* occupy depMdo™ entirely di,pr^SonSe to 5£ .Ifl ''th"' depressions m the rocky surfflcp nf ih,"^i t ^'>cir sue. The gularly scattered giadll ^6^1%? to^thttC^^^^^^ basins which are now occupied by lakes Much of f L^ • °"^ m this rocky lake country is accomDiLhed hv f h f f^^nage spilling over the rim of these basTs at theiMn^ ^*«!^«™piy tumbling downward from lake to °ake Many of h^s'^'; T^ sr^t^en-s^^^^^^^^^^ 14 rentian plateau, are features distinctly characteristic of regions of low relief which have suffered glaciation, for, while similar effects are produced to a degree in mountainous regions, these are comparatively unimportant because, in such localities, the slope of the surface is the controlling factor. Local. The region described in this report exhibits in general, the usual characteristics of the Laurentian plateau, but owing to the deposition of Pleistocene lacustrine deposits in all of the lower depressions of its surface, a marked topographic modification has been effected. Areas of rocky hill country characterized by all the topographic qualities of the plateau province occur here and there throughout the district. Around these, stratified clays have been deposited constituting what might be described as a depositional plain. DETAILED ACCOUNT. Relief. The Abitibi district lies somewhat below the gv .ral elevation of the surface of the Laurentian plateau, having an average height of from 900 to 1,100 feet above sea-level with hills and ridges rising here and there to elevations from 500 to 700 feet above the surrounding country. The lowest ele- vation in the region is the surface of Barriere lake which is 867 feet above sea-levelS while the highest point is Mount Shiminis which has an approximate height above sea-level (aneroid determination) of 1850 feet, giving a vertical range for the district of approximately 1,000 feet. Mount Shiminis is situated immediately southeast of the 40th mile post on the interprovincial boundary. This hay- stack-like hill is one of a number of prominent elevations of Huronian rock which occur along the height of land to the northwest of Lake Opasatika. These include the Labyrinth hills, between Labyrinth and Dasserat lakes, the Swinging hills, directly south of Dasserat lake, and the Kekeko hills, which form an east-west trending — nge to the northwest of Kekeko lake. All the hills of the region other than those men- tioned, consist of volcanics of the Abitibi group, the more pro- minent of these being the Abijevis hills which extend for nearly 15 miles parallel to the south shore of Lois lake, the Smoky hills lAocording to determinations by Mr. G. B. Hull, of the PubUc Works Dt 15 situated at the headwaters of the Smoky river, the Tenendo hills southwest of Tenendo lake, and Kamak hill rising adjacent to the south shore of Lake Dufresnoy. Next to the higher eleva- tions of Huronian rocks, the Abijevis hills form the most striking range of the whole region, having an elevation of 1,650 feet above sea-level. The following table of elevations has been compiled from the National Transcontinental Railway surveys, from the deter- minations of levels along the upper Ottawa by the Public Works Department, and from aneroid determinations by the writer. Lake Abitibi highwater level 870 feet ' Makamik lake 915 > Robertson lake 1 004 " Davy lake 1,003 " Beauchamp lake 1036 " Spirit lake '971 « La Motte lake 956 " ' Height of land east of Robertson lake 1,074 " ' Lois lake 99O " Duparquet lake ggs " Dufresnoy lake 907 " Height of land between Mackay and Kaka- meonan lake 950 " Lake Kewagama 953 " » Lake Dufault 95I " Kekeko lake 881 >« Caron lake 880 " ' Lake Kinojevis 880 " • Albee lake 882 " Barriere lake 86V " * Lake Opasatika 869 " ' Lake Dasserat 913 " a Ogimalake 913 « » Height (rf land between Ogima and Summit lakes 936 " « Mount Shiminis 1,850 " Swinging hills 1,600 " Kekeko hills 1 680 Abijevis hills l|650 " Drainage. The drainage of the region is about equally divided between the St. Lawrence and James Bay basins, the height ofjand passing through the map-area in a general northeasterly- ' Transcontinental survey. 'Ottawa River Regulation lurvey. !i m - f i 16 southwesterly direction but with a very sinuous course. The waters on the south side of the divide find their way into Lac des Quinse either by way of Barriere lake or through the Kino- jevis river. The drainage on the James Bay slope, with the exception of a few headwater streams flowing into the Harricanaw river, is entirely into Lake Abitibi, largely through the La Sarre and upper Abitibi rivers. Since the lower depressions in the rocky surface of the region are occupied by Pleistocene stratified clay, all the rivers have incised their channels in this material, and with respect to the clay, are in reality consequent streams developed on the surface of a constructional plain. Most of these, however, in places, have cut their way through the clay to the underlying rock, so they now consist of stretches of quiet currentless water, where they run over the clay, interrupted, at intervals, by rapids and waterfalls, where they are superposed on the harder rock. These streams have exceedingly wide and deep channels much out of proportion to the volume of water which they discharge. Thus the La Sarre river with a drainage jasin of approximately 650 square miles, is from 200 to 300 feet wide and is from 25 to 30 feet deep for several miles above its outlet. The channel ••■. 'he river is, therefore, over 15 feet deeper than the bottom of Litke Abitibi into wnich it flow This overdeepening is probably brought about by the -- ^ j of spring floods on the easily trans- port^ clay in whio'^ ^e channels of the streams occur. It is evident that all these streams are exceedingly youthful for they have as yet scarcely more than formed definite channels for themselves, u^t are the tributary streams well enough devel- oped to effect even a partial drainage of the clay belt, for stretches of muskeg sevoral miles in extent are common in the interstream areas. The larger rivers of the clay belt have sinuous courses, but no well developed meanders were observed. In the smaller rivers and creeks, however, both meanders and cut-offs have been formed. The island which occurs in the La Sarre (Whitefish) river a short distance north of the National Transcontinental railway, was evidently formed by the lateral diversion of the South river from an outlet at B to an outlet at A, Fig. 2. This capture and the consequent formation of a long narrow island were effected owing to the fortuitous concurrent incision of a meander in the La Sarre and South rivers at the same point A. This mode of stream capture is a common phenomenon in river development, one of the best known examples of the world being the diversion of the Ste. Austreberte b" the Seine at Duclair.' hu ■Nat. Geo. Hag., Vol. 7, p. 181, 18«6. ^1 17 Ab is characteristic generally of the Laurentian plateau, lakes are exceedingly numerous in ths region, but occur chiefly in the rocky hill country. Those which occur in the clay belt owe their origin to very slight depressions in the clay surface and are, therefore, exceedingly shallow. Lake Abitibi, for example, Seal* of mils* Fio. 2. Island in La Sarre riyer formed by the lateral diversion of the South river. although it has an area of approximately 335 square miles — only 50 of which, however, are included in the district under description — has a depth of 'jss than 10 feet throughout nearly its entire extent. Makamik lake is also very shallow, nowhere more than 5§ feet deep.' The lakes of the rocky portions of the district undoubtedly owe their origin largely to the scattered deposition of glacial ■According to Mr. Frank Johnston (Sum. Rep. Can. Geol. Surv., p. 132, IWl). 1 \i »l 18 drift over an uneven rock surface, since all of these lakes are hemmed in, to a large extent, by glacial material, but, to what extent the irregularities of the rock surface are due to glacial or preglacial erosion is not tdways evident. As in general the Laur- entian plateau imderwent dissection for a long time prior to glaciation, it might be expected that in so far as the present rock surface is of preglacial origin, the structures of the rocks would find expression in the topography and this appears to be true of some lake basins. Lake Kakameonan, Lake Dufresnoy, and Sills lake, all have a northwesterly-southeasterly trend parallel to the structure of the tilted volcanic flows in which they occur. The trend of these basins, moreover, is inclined at a considerable angle to the direction of glacial movement, so that they are probably preglacial valleys. In many parts of the region, how- ever, the rocks are of a uniform character without any well developed structure. In such rocks, normal stream valleys, modified by glacial erosion and glacial deposition, or glacial erosion American Jour. Science. Vol. 30. p. 23. 1910. 't"* ^M 23 tisQ plateau' furnish undisputed evidence that the Palasoioic seaa at times covered a considerable part of the Canadian shield, for the resulting sediments would be approximately as extensive as the seas themselves and much more extensive than their visible remnants, since they have liecn underKoing denudation more or less continuously since Palceosoic times. This wide distribution was evidently related to a moderate relief as is shown by the absence of clastic sediments in nearly all the outliers, except for a few '3et at their base.* From these lines of evidence it is inferr d that at the time the Palieoioic submergence occurred, the surface of the Laurentian plateau had but little relief, that the Silurian sediments formerly revered practically the whole of the country north of Lake Timiskaniing, and that the present topogrophy of this region is an exhumed ire^ilurian surface. That the limestone has been largely rci..oved from this depression is no doubt due to the soft and soluble character of the rock and the con'icqucnt ease with which it is denuded avuy. Assuming the above conclusions to be true, it is possible to indicate some of the events in the physiographic development of the region which occurred during this, the late i-re-Cambrian and early Palsozoic interval of erosion. Early in the period, possibly accompanying the intrusion of the Nipissing diabase, the Cobalt series was slightly folded or domed.' That this folding took place early in the interval seems necessary, in order to allow sufficient time for the denudation which followed. Subsequent to the deformation of the Cobalt series, the region was again base levelled. The evidence for this can be seen in almost any locality whei e the stratified members of the deformed Huronian occur, by the manner in which the beds are truncated at the surface.* After this period of base levelling, the region was again uplifted and further dissected until much of the Huronian, especially in the northern part of the Timiskaming basin, was stripped from the surface of the older complex. This denudation 'Lawaon, A. C, Bull. Gool. Soe. Amcr., p. 169, 1890. Adama, F. D., Jour, of GeoloRy, Vol. I, p. 238, 1893. Ulrich and Schuchert, Rrport of New York State Pslaeontolosist, p. 039,1907. Wilwn, A. W. C, Jour. Geo., Vol. XI, p. 6S, 1908. 'BeU, R., Geo. Soc. Amer., Vol. V, pp. 359^. Adams and Barlow, Memoir No. 6, Geo. Surv., Dept. of Hinea, Can., p. 342, 1910. Baker, H. B., .inn. Rep. Bur. Mines, Ont., Pt. 1, p. 226, IBU. LaFlamme, J. C. K., Can. Geo. Surv., 1882-3-4, Pt. P. > Rep. Ont. Bur. of Hinea, Vol. XXI. p. 38; p. 205, 1907. Vol. XXIII, Pt. II, p. 24. 1908. Prel. Rep. on Gowganda Mining Uiv., Geo. Surv. Bran., Dept. of Mines, p. 28 1907. < See Fig. 7 in the "Prel. Rep. on Gowganda Min. Div." by W. H. Collins: Gool- Surv. Bran., Dept. of Minca, 1909. 24 was finally temlnated by the Palvozuic •ubmernrnce, and the deposition of limestone containinR fossils which have been assigned to the Clinton and Niagara cpochs.J It is not possible to ascertain the precise time at which the PaliPosoic sea retreated from the region for the last strata deposited have been long since eroded away. But from Ihe thinness, limited extent, and limited range in age of the rocks which remain it is probable that the submergence was of short duration. ^, Since the withdrawal of the Palooioic sea the region, as far as known, has always been a land area, but has stood so near sea-level and has possessed such a low relief that it has suffered little erosion. We have no information as to whether a Creta- ceous peneplain* extended over this part of the Laurentian plateau or not, but if such a plain was developed, it was evidently formed upon the Palieozoic sediments which filled in the Timis- kaming depression. u- i i In the preceding pages the broader physiographic develop- ment of the Timiskaming region has been outlined, m so far as the record of events was available, but the origin of the inore detailed topographic features has not yet been discussed. The drainage system of the Timiskaming basin presents some pecu- liarities for which no satisfactory explanation has been given. Some of the linear depressions of the region arc evidently related to the structures of the rocks in which they occur, since Ihcy lie parallel to their strike. Such valleys as that occupied by the Wendigo-Raven chain of lakes which parallels the trend of the eastward dipping Cobalt series, are evidently of this class. In the Gowganda district, W. H. Collins has pointed out, that a relationship exists between some valleys and the contact between the Nipissing diabase and the Cobalt series'. The majority of the more prominent linear ilcpr, s. ons of tli«^^r?gion, however, such as the Timiskaming valley and the Mointreal River gorge, are in no way related to such geological conditions since they maintain their linear trend through all the various rocks of the region, without regard to their structure or character. In order to explain the occurrence of these peculiar valleys, it has been suggested that they owe their origin to faulting*, but the only evidence in support of this, is the linear oharacter «Anii. Rep. Geol. Sonr.. Vol. X, p. 283, 1897. •Science New Series. Vol. IX. pp. 890 and 230, 1896. Jour, of Geo., Vol. II, p. 658, 1903. 1909 •Prel. Rep. on Gowganda Min. Div., Geol. Surv., Dept. d Mines. Can., p. 12, >. •HUlcr. W. G., Ann. Rep. ol Ont. Bur. of Minei, Pt. 11. p. 28, 1905, p. 38, 1907. PirMon. L. v., Amer. Jour. 8ci., Vol. 30, PP. 2M2. 1»10-,^ .... Hobhi. W. H.. BuU. Geo. Soc. Am.. Vol. XX, pp. 141-160, 1911. Miller, W. G.. Eng. and Min. Jour.. Vol. 92, p. 848, 1911. 'H 25 of the vftllpyM themiielvrti. In a rtcrnt paprr publiiibed in the EnginwnnK and MininR Journal, W. G. Miliar NugReitU that Lake TtmiiikaniinR oocurM alimR a fault piano, and that the amall extent of the NipiiwinK diubttw? on the ea«t hide of the lake 18 proh.iblv due to the fact that the west side in on the down- thrown Hide of a fault and for that rcanon the diabanc has been rem'- d by denudation on the one side while remaining on the other. An examination of the Reological map of Lake TimiMkaminK' HhowM, however, that .me side of the lake has in reality suffered little or no verticia displacement with respect to the other, for on the east side of Lake TimiskamlnR in the vicinity of Bale des Perec, ridK<'s of Huronian quartjito occur lying on granite, the contact maintaining a fairly uniform eleva- tion of a few feet above the lake. On the west side of the hike, the same contact is exposed fringing the lake shore for a distance of over 2 miles. It is evident, therefore, that the pre-Huronian base levelled surface stands ut approximately the same elevation on lK)th sides of the lake and has net been vertically displaced to any great extent. This being the case, it follows that no great movement of the rocks on the opiwsite sides of Lake Timiskaming relatively to one another has taken place since the Cobalt series was deposited. Furthermore, it is not apparent, from an examination of such geological maps of areas in the Timirtkamiiig region as are available, that that there is any change in the distribution of the rocks relative to the courses of tHe jinear valleys — an effect that would certainly be very noticeable if the valleys marked the outcrops of faults having considerable displacement. On the other hand, if it be assumed that these valleys are not related to deformation, and have been developed by normal physiographic processes there is here the anomalous condition of a rectangular system of drainage, in a region of uniformly low relief, rnd yet unrelated to rock structures. A.s far as known to the writer, such a system could only develop normally by thesupc-position of topography from a once overlying series of rocks, presumably in this case from the Palteozoic sedi- ments, since these as far as known, are the only overlying rocks which ever occurred in the region. This hypothesis, however, would give the linear valleys a post-Silurian origin whereas we know the Lake Timiskaming depression had been excavated to a considerable depth, at least, prior to the Silurian. In the above discussion of the origin of the linear valleys of the Timiskaming region it has not been possible to obtain a definite solution of this complex physiographic problem, but it has been shown that while the linear and rectangular character of the major valleys of the district is suggestive of deformative move- ■ll*p 18A. Geol. Surv., Dept. of Hinei, Can. I n IP "^ 26 „ nt« Other evidence must be secured before this hypothesis ' ' bettXhS If these valleys "e 'elated m any way \ipfnnnation then some evidence of this such as faulting or brStioS shoSd be observed along the borders pr ends S theTepSons If, on the other hand, they owe the.ronpn to normal stream erosion the problem must be attacked by stud^M the physiographic development of the region. By iSStion i^ these%rrious ways, the mode of origm of th« oeculiar topographic feature may eventually be ascertained. •^ The hit important event in the physiographic development of the Timiskam^ing region is.closely related to the L^^^^^^^ 5>SrelrigSoro5V"re;^^^^^^^^^^ STdXs t^e glacial an'd post-glacial depo«|ts - f -a|or features is probably preglacial m origin, and that the erosive krf on of the continental glaciers was largely limited to the oroduc^on of the rochesmoutonndes rock surfaces so character- f,Ho of Xciated areas. The deposition of drift by the continen- tal dLiershoV^^^^^ new type of topography on the fegion so that although it has the low relief of mature deve- opment, its drainage system, composed of X""?„^;;eE^ui*"^'n and urecipitous river courses', is exceedingly .youthful, in nortions of the region a further modification in topography ws^ effected by the deposition of lacustrine clays which produced Klconstructional plains in the lower depression of {he region^ ThL event practically concluded the physiographic history of the regfon! denudation since that time consistmg merely of a slight amount of stream dissection in the unconsohdated glacial and post-glacial deposits. CLIMATE. The accompanying table of meteorological observations than tho" for the more southerly portions of the area. The oUovring dates for the formation and breaking up of ;ce on Lake AbUibUre of interest to persons desirous of visiting the region at these seasons of the year. > See page 104. ' ^e page 13. ►-I I 27 Apr. 11 Apr. 28 Apr. 30 Apr. 11 May 19 May 20 Apr. 25 Oct. 28 Nov. 11 Nov. U Post. Wiiiior, W. J., Sum. Rep. Can. Geol. Surv., p. 130, 1001 ■; -for-nation supplied by Mr. Dricver, factor of the Hudson's Bay Co., at Abitibi LAKE ABITIBI, ABITIBI DISTRICT, QUE. TiMUBATOBi, PmaprrAiioN, inc., roa the Yiaks 1897 to 1910 iNctrmvi. Month January. . February, March April May June, July August ^September t>ctobcr November December, Annual Average summer temperature 57-2°; 3 months, 811*. Average date of L-ist frost. June 8. Average date of first frost, Sept. 14. AGRICULTURE. The large areas of post-glacial clay in this region afford a very good soil for the growth of hay, vegetables, and the hardier cereals. At the Hudson's Bay Company's post on Lake Abitibi, land has been cultivated for a number of years with excellent results, 200 bushels of potatoes being produced during the past season from an area of less than three-fourths of an acre All of the country adjacent to the National Transcontinental railway has now been subdivided by the Crown Lands Depart- ment of Quebec and a large number of applications for land trom prospective settlers have already been received 40591—3 28 FLORA AND FAUNA. The forests of this -gion belong to a^^^ inte-e^ate «one between the Canadian and H^^Xn flora in the or to the subarctic subdivision °^ C^J^^^^th" Geological il^r The tX:^eJ:nas,frZ.rr^. in the district spruce (Picea nigra), ^^JbanftiaS, white birch or canoe jackpine or V^tchpm^JPinv^ bank f^^ ^^^ birch ^B^'^^^^^W'rtif Giffd rPo^i^sbalsami/era;, whit^ (Abies balsama) , balm of }f'^^fj^°^{. (larix americana) , cedar (Thuya °ftS black SfFrait-mus sambucifolia) yellow birch CBetuZa '"««°^,^'^^5 .^^ ' f F?/r«s pennsi/Iwimcus; redmaplefA<^r.ru6rumJ,wildredcherTy^rynt^^^^^ ^^.^^ alder Alnus vindus and ^f""''J"^"^' and Vacdnium palustrus), blueberry fVacnmum "'f?^^^^Zpulus) , low ^j/mbosom;, hghbush cranberry j^Ktrfturnum^ bush '^r^^^^"yP^y^''^''^^^^rSnirom a commercial The most important tree »n.*{^^^J^f J"" ' j^^here in great standpoint is the ^ack spruce wj^^^^^^^^^^ ^re wood, these forests, ^Jj',^** White and red pine trees occur The most northerly of these observea were ui beyond this removed by the lumber compamM, ^"*?'™S "white River and some scattered white P'M """°; J^^ timber limit Lmnber Company c.rn^o„jper.«oM M. B.,^^^ ^ STnd^'rSr.hirShettlog .Jung in theregionfor 'N 29 ties. There is considerable canoe birch in the region which reaches a diameter of 18 inches to 24 inches, but owing to the fact that birch will not float in water, the difficulties of transportation render this, at present, valueless. Tamarack were at one time abundant in the muskegs of the district, but these were all killed by the larch saw fly about 20 years ago. Cedar, poplar, and balm of Gilead are locally abundant, chiefly along the shores of the lakes and the banks of the streams; the cedar occurring in the rocky districts and the poplar and balm of Gilead in clay areas. These trees are not of sufficient size or quality to be of importance commercially. There is a striking localizatio'x of the forest growth in this region, relative to the character of the soil or other special con- ditions in the respective localities. In the partially drained portions of the clay belt, the forest consists entirely of black spruce or if the soil is very wet, of tamarack and black spruce. Ihe first constitutes what is known as the black spruce swamp and the second, the tamarack swamp. Along the margins of streams and rivers where the drainage is exceptionally good, poplar and balm of Gilead grow in great abundance, while in sandy areas Banksian pine is the dominant tree. In districts where sand is extensive, large areas are occupied by this species and are described locally as jackpine sand-plains. If, however a forest hre has swept over a region within recent decades, a thick growth of poplar and birch is generally present. In some places, niore especially m rocky areas, a mixed forest occurs, and here the red pine, the white pine, and the jackpine, the birch, the poplar, the balsam, and the spruce may stand side by side. Ihe fauna of the Abitibi district includes the usual species found in northern Ontario and Quebec. Of the larger game the moose (Alee an^ricanus) is most abundant and al- though froni 50 to 60 of these are killed, each season, during the . inths of June and July by the Indians assembled at Abitibi St, the numbers do not seem to diminish. Red deer (Viraim- anus canacus), and caribou (Rangifer caribou), arc both present in the region, but are not very numerous. K„ J^T ^J^^ ^^a"?« animals have been trapped for many years by the Indians and many varieties are consequently being gradu- aUy extermi ated. This is especially the case ^th thf beaver Sn^i! f^ °?[y T ^i"" °^ ^^'"^^ °°^ '•<^'°^*°- It was formerly customary for the Indians to take care not to kill all the beaver ^Z^ '?if P^''*'^"'^'' Locality in their hunting ground, but of late years this custom has been abandoned. The common fur- h- ■ng species present in the district include the otter (Lutra Jh^l?*'*' ^/ "]'^^ (Putonus vison), the fox (Vulpes vulgaris). the marten (Mmtela americam), the fisher (Musiela p€nntt7,li), 40591— 3J 30 rl S°"f*^?wA S the"ki.nk (,«epM«. »n,) tb. rS Wilson, M.E.. Sum. Rep. Geo. Surv. Bran., Dept. of Mines, :;an., p. 175, 1909. Miller, W. G., Eng. Min. Jour., Vol. 92, p. 648, 1911. iSlf' ^*°' °' ° ^*^ "' ^"^^ Township, Pontiac Co., Que., pp. 18-17, Pago 43. 'See page 83. • Geo. of Can., pp. iO-61 , 18«3. * Ann. ''«p. Bur. Mines Ont., Pt. 2, pp. 40-42, 1905. •Eng. Min. Jour., Vol 02, p. 648, IPll. Dr Miller's classification of the Huronian into two series was based on an unconformity between greywa ke and arkose ocTuS on lot 4. concession XII of Lorrain township, nSS district, Ontario, where angular fragments of the grey- wlcke are enclosed in an arkose matrix. Unconformities be- Tween a "greywacke conglomerate and an overlymg arkose sSs" we Slso mentioned by A. G. Burrow« in a marginal note on a map of "part of the Gowganda silver area," published by the Onfario BureL of Mines. Elsewhere in the region, as far £^ has been observed, the various members of the series are in conform- able relationship to one another.' so that the unconformities Fi8 4 Diagrammatic «M-tion showing the geological relationship, of the rocks occurring in the Timiskaming region. that have been described are probably interformational in char- acter and do not necessarily signiiy a break of any importance m *'^ ThfcobllttSs now known to occur in the Timiskan.„g rPffion and vicinity throughout an area of approximately 20,00U SremSel Tut this is probably a me.3 fraction o its former extent, for i^uch Huronian, having the same lithological cha- Scter a Id geological relationships, occurs in outlying districts SI that on Lake Chibougamau. about 300 miles to the ""'■'SX'^bobalt series and the rocks of the older complex are intruded by the post-Huronian or Nipissing^ diabase, fn the older complex, these intrusions occur a °^08t entirely a« dvkes- in the flat lying Cobalt series, on the otaer hand, they Se large y sills. The time at which these rocks were intruded cannot be definitely fixed from the geological evidence obtainable -T^JVI »GoW^da''MTnii' Division-: Geol. 8urv., Dept. of Mines. Can.. p. 32, 1909. ,,„ ..„ » Eng. Min. Jour.. Vol. 92, p. 648, 1911. 33 in the region, although they were evidently not only intruded but deeply denuded before the Silurian submergence.' However, from the facts that the Nipissing diabase is lithologic- ally similar to the igneous members of the Kcweenawan series, that it was intruded in late Pre-Cambrian, or early Palaeozoic time and that dykes and sills of the same rock type occur throughout the whole region from Lake Timiskaming to I-ake Superior where the Keweenawan rocks occur, it is exceedingly probable that the Keweenawan igneous rocks i. d the Nipissing diabase are all portions of the same magma intruded during the same period of vulcanism.' A number of outliers of Silurian limestone belonging to the Clinton and Niagara epochs' occur in the vicinity of Lake Timiskaming, one of which extends from the north end of that lake to Evanturel township, a distance of 40 miles.* These outliers occupy a pre-Silurian depression beneath the general level of the Laurentian plateau and for that reason have been preserved. There is no evidence that the region has ever been below sea-level since the Paleozoic, the Silurian limestone, with the exception of unconsolidated Pleistocene and Recent deposits, being the youngest rock in the whole country. The glaciated rocky surface of the Laurentian plateau, in the Timiskaming region, as elsewhere, is largely hidden beneath a mantle of Pleistocene and Recent deposits. Through- out the larger part of the region these consist entirely of boulders, gravel, sand, and till, materials of glacial or Huviogla ial origin which were deposited from the last Labiadorian ice shtet, but, m the northern part of the Timiskaming region and throughout a large part of the James Bay basin, are overlain by stratified clay and sand which were laid down in a huge lake which covered this area in post-glacial time. This lacustrine epoch represents practically the last event in the geological history of the district, for denudation since that time has scarcely begun even in the unconsolidated easily transported clays. LOCAL. General. In this subdivision of the report, a general account * u- *u? • S?°'°Ky °f the country south and east of Lake Abitibi is inserted for the convenience of those who are espec- ially interested in the economic section or who for other reasons, > See page 22. 'Jour of Geo., Vol. 13, pp. 89-104, 1905. •Ann. Rep., Geol. Surv. Can., Vol. 10, p. 289, 1897. « Sum. Rep., Geol. Surv., Can., p. 221, 1904. 34 wish to omit the more detailed descriptions of formations which follow. ,. , i J 1 • I „.» With the exception of unconsolidated Rlacial or post- Klacial deposits, the rocks of the particular district to which this report refers are entirely of Pre-C^ambrian age and, for the most part, belong to the older complex which underlies the Huronian, Cobalt series. Ihese ancient rocks may be subr - vided into two classes, the first of which consists of deformed and metamorphosed surficial rocks (that is rocks formed at or near the earth's surface)— Abitibi group— and the second of batholithic masses of granite and gneiss— Laurentian?. Abitibi Group. General.— It has been customary to call the volcanic flows and associated sediments which form the surficial portion of the older complex occurring in the Timiskaming region, Keewatin, thus assuming that these rocks are equivalent in aire to, lithologically, similar rocks occurring in the vicinity of Lake of the Woods and in other localities to the north and west of Lake Superior. It is pointed out in the pages which follow however, that this correlation has been made largely on litho- logical grounds and is probably incorrect. For this reason the name Abitibi group has been substituted for Keewatin in this For descriptive purposes the group may be divided into two sections— (1) the volcanic complex with which is included some schist and amphibolite, chloritic rocks, slate and ferru- ginous dolomite, and (2) the Pontiac series which consists largely of metamorphosed clastic sediments. Abitibi volcanic complex.— Throughout the northern part of the region, the predominant rocks belong to a great volcanic complex consisting of lavas which range in composition from basalt to rhyolite, but the types of intermedia* ^ composiuon are most common. There are associated w.n these some nuartz porphyry, diorite, gabbro, diabase, amphibolite, horn- blende schist, chlorite schist, sericite schist, ferruginous dolomite, and slate, as well as intrusive rocks lithologically similar to the extrusive lavas. ,.,..■• u u The various rocks comprising the Abitibi group have all been more or less metamorphosed, but these alterations have been, largely, mineralogical rather than mechanical, for the schistose rocks are generally of local extent. The hornblende schist and amphibolite are usually associated with the gramte bathoUths and have evidently resulted from the metamorphism of the > See page 43. \m 35 basalt and related rocks under the contact action of the intrusive. Since sericite schists may result from the mashing of sedimentary or igneous rocks, it is not always possible to ascertain the original character of the rocks from which these wore derived, but, in places, th(: geological relationships are such as to indicate that they are metamorphose«] quartz porphyry or rhyolite. The ferruginous dolomite and dolomitic sericite schists are believed to have originated from quartz porphyry, aplite, and similar rocks under the action of hydrothermal solutions. The slates are presumably sediments, but whether these are interbedded with the lava flows or have been subsequently infolded is not known. In a region where the rocks are, on the whole, not very well exposed it is not always possible to ascertain the structural or stratigraphical relationship of the volcanics of the Abitibi group, but, in places, the attitude and trend of the lava flows can be recognized from the change in texture from centre to margin, from the occurrence of enheroidal, amygdaloidal, and flow struc- tures at the surface of the flows, and from their relationship to associated sediments. Wherever the structure of the rocks was ascertained they were found to have a vertical or nearly vertical attitude, the lurike varying from east and west to north- west and southeast. PoNTiAC SERIES. — In the southern part of the region, the prevailing rock is » fine grained mica schist or gneiss, with which is associated seme hornblende schist and amphiboiite, and which passes on tho no'th into mashed arkose, greywacke, and conglomerate. It is believed' that these sediments and the mica schist belong to the same series, the mica schist being the metamorphic product resulting from the contact action of the intrusive granite on arkose and greywacke. All these rocke are, therefore, classed together in the Pontiac series. The mica schist contained in the Pontiac series is a fine grained rock consisting essentially of quartz and biotite with usually some feldspar. There is generally some sericite present and the biotite is commonly, to a large extent if not entirely, altered to chlorite. When fresh, the rock presents a bright grey appearance, but on the weathered surface is gener^ly rusted, owing to the oxidation of the sulphide of iron which it contains. In places pyrrhotite or pyrrhotite and magnetite occur interlaminated with the schist, in zones which may be several feet in width. Irregular veins and lenses of quartz strung out along the foliation of the schist are also common. Here and there, hornblende schist and amphiboiite are asso- ciated with the biotite schist. The relationship of these, owing ■ See page 73. to the alwence of cxpooures, cannot always be ascertained, but in Bome places they occur in bands conforming in strike and dip to the adjacent mica schist. The hornblende schist is a dark, fine grainecl, Rrcen rock consisting of hornblende and quarts with or without feldspar, and, in places, appears to puss transi- tionally into mica schist by a gradual change in the ferromag- nesian constituent. The amphibolites are coarse green rocks which vary greatly in texture and raineralogical composition but consist chiefly of amphibolc — hornblende, tremolite, or actinolite — and feldspar or quartz with sphene, biotite, and a carbonate us accessory constituents. Owuig to the excessfive variability of the amphibolite, the rock weathers in a most irregular manner presenting a peculiar botryoidal appearance in places. The manner in which the amphibolites and hornblende schist originated has not been definitely ascertained. It is most probable, however, that the fine grained hornblende schists are, in part at least, metamorphosed ferromagnesian sands and that the amphibolites are metamorphosed lavas, contemporaneous in age with the sediments from which the schists were derived. The evidence upon which these conclusions are based is cited on page 74. , . • . The mashed greywacke, arkose, and conglomerate, belonging to the Pontiac series, extends in a belt nearly 2 miles wide along the northern border of the schist. The rock predominating throughout this belt was originally a ferromagnesian sand con- sisting of quartz and f-ldspar enclosed in a matrix of chlorite . i,! sericite. This paa^es into arkose, locally, the rock at :nf points consisting of quartz, feldspar, and pericite, with very little chlorite. It also contains mashed pebbles „nd boulders of granite, rhyolite, and quartz porphyry, in places, and thus passes into conglomerates. In all of these rocks the quartz and feldspar fragments have been greatly corroded on their maigin or have been partly recrystallized into a fine grained hornfels similar to the schistose members of the series. Structurally the rocks of the Pontiac series appear to form a monoclinal succession dipping towards tho north, away from the granite batbolith. The strike varies locally from northwest- southeast to southwest-northeast, but in general the structural trend is approximately east and west. Since the rocks of the Pontiac series and those of the Abitibi volcanic complex largely occur in separate areas, and since, even in places where they are adjacent to one another, the geolo- gical conditions are very obscure, their relationship can only be inferred from their general distribution. At the points where the greywacke adjoins the volcanics of the Abitibi group the two formations possibly pass gradationally into one another, for no definite contacts, conglomerates, or other evidences of i. ««J 37 unconformity were olwervrd and the two rocks rrsemble cni* another m closely that they cannot be diHtinguiHhed in the hand upecimen except from thf presence of grains of quarti in the greywacke. The distribution of the I'ontiac Heries, however, in a narrow belt intervening for a jliHtiince of 50 miles between the volcanic complex of the Abitii)i group and the immense southern batholith of graniti- and gneiss, suggests that the occur- rence of the schist in this roliitionship is not p. mere coincidence but that the Pontiac series is strntigraphically below the adjacent Abitibi volcanics and has bc«n tilted up into its present attitude by the intrusion of the granite batholith. This evidence, however, is insufficient to warrant a positive conclusion so that the stratigraphical position of the Pontiac series in the Abitibi group must remain for the present an unsettled problem. Granite and Gneina. Both the schists of the Pontiac series and the volcanics of the Abitibi group are intruded by batholithic masses of granite and gneiss, ranging in size from small isolated intrusions to a huge massif of which only a marginal portion, intruding the Pontiac series on the south, occurs within the confines of the region examined. The smaller batholithic masses occur in the northern part of the region and are in igneous contact with the Abitibi volcanics. Since there are probably granites of varying age present in the region, it cannot be assumed that these masses are connected at depth with the larger southern batholith although such may be the case. Practically the whole of the southern part of the district mapped is occupied by a complex of acid igneous rocks of various kinds, which will be designated, for purpose '>f description, the southern batholith. It consists largely of grt ) and gnei.s8, but these rocks pass locally by loss of quartz aud orthoelase into quartz diorite or diorite. They vary i^reatly in texture and composition from point to point anu are cut nearly every- where by dykes and masses of aplite and pegmatite, the whole forming an igneous mass of a very heterogeneous character. The junction of the southern batholith and the Pontiac series is marked by a contact zone several miles wide in which dykes and irregular masses of granite, aplite, and pegmatite intrude the schist, increasing in size and numbers towards the south until finally only isolated blocks are observed. These blocks, or xcnoliths, in places, maintain the same attitude and strike as the schist farther north, showing that they have not been tilted from their original position; in other localities, however, they lose this relationship and are cut by numerous 38 dyke« being faulted »^"«'. ^»^.", P'Sa he ma^nner of intrunion country to the wert °f J^lJ^J ^^^ kction>numorablc narrow rirofrho^^rLrpe^UaC;^^ P-l.el the Ceavage. lain at no^ great '^^^'^ }:i^^fli,^{J^^i Ti^., the Lake of this rock arc very ??'"™°'^ *£^k f mid Lake Abitibi batho- Dufault, Gauym Lake, K"^^*^" \S m ,"«. The rocks of all thene lith^havingdrnmeteisof from 5t num. .^ .on«i«ting intrusive masses have ^he same "J'^"'"'*' j^j j, ^^^ locally int() of »H,th hornblende and '''"^i'^/J^J^^eSt. '«"*«« is repres- granodioritc and dionte mo that a granite m j j^^^,,,, ^,, ILied. The ferro^Rnesmn ^^^^'^^^^^.^rhy gr.en seridte. chlorite and the Z^'^^Pf JlKaller massivos have given the These alterations m son., of the smaller ^^^ ^^^ ^j istic of such maginatic '"^'^■^"^i.. /„f rhyolite, quartz porphyry, Abitibi group are myuded by dyk^^^^^^^^ .^ p, aplite, and pegmatite and "« ""K"^ ,u ThV contact of the into hornblende schist and a«»P^'^°'7^_ui„" ;„ places, and granite is ^^^''^'^^'^ '"til^uth thTgr^^^^^^^ i« fi»ed with uear the margin of ^he bathohth tu. gr .^ angular, subangular, P^rounded blocks^^^^^ ^^ ^^^^^ with which are *««°"f ^5,^™P~'to be complete gradation blende granite so *h^**^"VloubtecUv belong to the Abitibi from blocks o rock which u ^'^^"JSleftherefore, that these grouptohornblendegramte. K isprooam^ ^^^^^^ ^^ ^^^^ bS^ oTTS volctirrSe^than by differentiation from the granite magma. Cobalt Series. surface of the Abitib, »'|"P '"^^'l'™ p „"f clastic .cdimcnte so nnd ridgoH or Jtmnll MolRtod oxpoKiircn. Thi-v nro confined almoKt wholly to Boi«(hatp|, Dawrnt. and Dt-itor townnhipH. The (lobalt Herif-H may Im- Hulnlivided »r of these occurring even in a single outcrop. The matrix varies from 11 coarse arkose to fine grained slate like rock, the latter being tlie type described by Logan as •■Wc«l ."ccession i. t^ 'ThetS^USB^ As'?.^«.ber.b«.n,«., .« "» S:S;« to the .b».ee o>str..,6»«.» ij,| -f^-JJ^S anticlines and synfl^nff: , ,. various rock types comprising The modes of origin »* t'^f "^"'"'u -^^ ^ later section of the the Cobalt series are discussed at ength in a ^.^^.^^ ^j ^j^^ report. From a «^o{|?'J"^X^ated to environmental conditions different members which are related to env^ ^^^^ ^^^ of deposition, the conclusions reached we^n ^.^^^ j^^,^ upper conglomerate '«5X^*^,J,*rtratiU^^^^^ argiUite, fd TrCi ^rJf l^ttS SKnd wefe laid down during an interglacial penod. Post-CobaU Series Inlrusives. NxHssiNO. -B-rJSr iUruTn^^^^^^^^^ under description, dykes "J^ J^J^Y^^e vaiy in width from a older complex, are very common. ™\^J7^e of some of the few inches to several hundred feet ana in ^^^^^^j ^^j^^ larger ones outcrop "^.^.X^'J^Surerof diabase which have There are also a few '««1^*^^J.^^^^^^^^^^ no continuity of outcrop ^ff,"^' *S of the Cobalt series and sills which spread «"* f "^^ the cont^f ot .^ ^^e dykes is the underlying co°^Plej- ^;»« J^^J^^g°oUvine Ind the other of of two varieties, one o^J^J^^^^^^^f^X^hat in other parts o the which is o ivine free. .[^""^.J^V diabase intruded the olivme Timiskaming region, t'^® °'V''i'^? ^'ck^^ free variety, it is believed that thi8 rock ^«t y^^.^^ j^,, ji^ba^e ITwherSeKLrtLtroTmicrographicintergrowths -^^^iSiTdlabase dykes -- -* ^-^^^^^^^^^^^ ^rtl of the Cobalt series a°y .^^^?'^ '" J^f uthological similarity.to unaUered character a^JJ^^XfS of the Tfrniskaming region %l^r^ro^^l^r'^"^^'^^^^ with the Nipissmg diabase. _Rptween Oilier and Renauld lakes an eCrf^rlSJniii-S »' '»-'• ^"■''"' °^" 41 cutting the conglomerate of the Cobalt series. This rock con- sists of large phenocrysts— an inch or more in length— of albite, which are enclosed in a matrix of quartz and plagioclase with some chlorite, epidote, sphene, and carbonate. Pleistocene and Recent. The ancient Pre-Cambrian rocks thus far described are largely hidden from view by a mantle of Pleistocene and Recent materials which are classed as glacial or post- glacial according to the time and manner of their deposition. The lowermost of these deposits consist of sand, gravel, clay, and boulders which are partly glacial and partly fluvioglacial in origin. The fluvioglacial deposits are rudely stratified and usually take the form of kames or outwash plains. Throughout a large part of the region, the older Pleistocene deposits are overlain by stratified clay and sand .sediments which are evidently of lacustrine origin. The stratified clay is uniformly bedded in layers averaging about one-half inch in thickness, the beds, in some localities, being separated by a thin layer of calcium carbonate. Locally, the clay becomes arenaceous and in these places a bed may contain two or three subsidiary layers due to variations in the sand content. The stratified sand is found chiefly in the vicinity of glacial or fluvioglacial deposits in which sand is abundant, and generally overlies the stratified clay. DETAILED DESCRIPTION. TABLB or FOEMATIONS. In the following table the geological formations are arranged in descending order with respect to age. Quaternary. Post glacial Stratified lacustrine clay and sand. Glacial Gravel, sand, boulders, boulder clay. Unconformity. Pre-Cambrian. Keweenawan? Nipissing diabase, sye- nite porphyry. ill ^ h 42 Igneous contact. Cobalt aeries. (Laurentian?) • .Conglomerate. Arkose. Greywacke and argmne. Conglomerate. Unconformity. Granite and granite gneiss. Igneous contact. Abitibi group (Keewatin?) ^.^^ ^^^^^ ^^^ horn- Pontiac series blende schist. Amphibolite. Greywacke, arkose, ana conglomerate. Slate and phyllite. Ferruginous dolomite. Chloritic rocks. Schists and amphiboUtes. porphyry, rhyo- Abitibi volcamcs J^^^ andesite, gabbro, ba- salt, etc. It may be observed tbat in the aW U^^^^^^ the various series or groups of rocte have Dee B ^^^ ^ and have not been assigned definitely to a^^ ^^^^ ^^^^^ ^ subdivisions of the P^^-p^M^^^Xittec for the Lake Supenor the international g««l°»*=„^l„"Jbecause there is considerable Sbt'as t"othe7l?crorth«t'^ -k groups in the general ^^n'TS'been customary in ^^^^^^^^^S^Z^S^^^i^^^^ the rocks of the older comple^, whjh unJerU^^,^^^ ^^^ on a lithological basis, ^°£ *^° S io "^^^^^^ seated granite watin, the former e™ Jl'^^^.^PSlrocks consisting chiefly of and gneiss, anu the latter to the ^mci^ however, that both volcanic flows. . It is now^b^P^^JJ^cks which differ greatly tir].eSpUe°rr>''«" ihlch^tf p,.bJb>, i.corre«. — Tjour. rf Geol.. Vol. 12. PP- «0-104, IMS. \% 43 rnnJlt^t ^^^^^.^^'^^^^ >n this report, some of the volcanic ?Pon thin tK°^f'^ Keewatin have suffered much less altera- SurP HnZ T!!*' ^'^^ '^™^ mineralogical composition and texture. Undisturbed and comparatively unaltered dvkes of andesite and rhyolite also occur cutting across other membeS ald^n^/rP "it'^ ^^^t'' /"^•''^^ °' "«^''y vertical StHuT Collins has observed flows of andesite and rhyolite which were much less folded than the volcanic rocks with wEh Thev ZwIh"^'-'^- .^" f ^^''' observations indicafe that the prolonged period of vulcanism during which these lavas were extruded was interrupted by orogenic dis .nces whTch are expressed in structural unconformities, and that at 7ealt two series of volcamcs are probably represented. Fur hmnore detailed geological work in the Lake Superior region hiXwn volcanic rocks to be present in every Pre-Cambrian Veries of thatregion, so that the lithological similarity of the vo cliUc rocks occurring in the Timiskaming region to those of the KecT^- tin IS not a secure basis for correlation. For those reasons it has been deemed advisable to substitute the term Abitibi group for Keewatin, this name to be applied to the surficial rocks of the SteaZ'SeS.""*'"^^* ^^^ *^^ "•"*-'<= (Laurentian?) An extensive area oi greywacke, arkose, conglomerate and mica schist be onging to the Abitibi group, occu "fn th^ h^Tvu^^f *^''f iT ^^' r'^°.'' °^ lithological descriSt on have been separated from the other members of the group and have been designated the Pontiac series. While these rocks have thus been differentiated from the other surficial membere of the older complex It is not intended to imply that they are necessari y different m age. It is shown in th aiscussbn of the structura relations of the Pontiac series that there is evidence wh ch suggests that the series may underlie the Abitibi volcanoes Tpnt f """^iltf °* T t^'^^orth. On the other hand the occur! rence of pebbles of gramte and rhyolite in the conglomerate indicates that at the time the Pontiac series was deZited rocks similar to both the Abitibi volcanics and the Enic nr^^nt1wP^'*^'^'''^J'"t'«*'!°8 "«^'°"' ^"'J' if these are now nfrt! nf tK^ lT.°u' ^^"^ ^"°**^^ ^^"""^ '""«t be younger than parts of the Abitibi group and the granitic (Laurentian?) complex, and a great erosion interval is represen ed. Despite the incompleteness of our knowledge with regard to the age and relationship of the Pontiac series it has befn deemed advfs- able however that these rocks be separately designated because (IMhey are lithologically different from the other portions^f * Personal communicatuNi. 40591—4 H 44 the Abit^bi group; (2) \b^7/^,7Ju'Si"SioS''«^^^^^^^^^ STeiSSloS to a singlejeries. Laurentian has been * In the Lake Superior region, the m^^j ^^^^^ .o^ks which assijmed to those granites '^^.'iK^fnhat geological province, is Sender than the.senes which in tt^^t g^ g^.^^ which have called lower Huronmn. . .f„"\^*Thf Tiraiskaming region intrude been classed as Laurentian in the i|,^ ^^^i^g genes, etc^ Bedimentary rocks-Pontiac series, i^nu structurally, wSch are very similar, both htbolo^ca y ^^^^^^^^^ these To the Lake Superior »°^f ' """J^^'^signiBcance is imp hed rocks be classed as Laurentian, an age ^«^.^^^^ „„t ,^ this which is probably incorrect. It^>gjt ^^^^ „e fanites of Connexion that it «X whXn the region north and west different ages in the complex wnicu ^ ^^^ m the of Lake Superior '^'^deriies the^^^^^^^ ^ut, owing to Timiskaming repon underlies the ^o ^^ ^^^ ^^ j jhe the complex. 8eolo8\^^i,3Sary series, it is not possjle to ?ot heseMSns it «f- f,f tTprS^^^^^^^^ should have been restricted to the F jj^^ble throughout the Ldthus^have^rendered^^he^ame^^^^^^^^ ^^p^^.^^ g,„log,eal P"%%he slightly disturbed Huronianroc^^^^ the nLe Cobalt series is gdJoUo^g^^ ^^^^^^^ j ^^e recently adopted by W. G- MUler m i^ v ^^^^ ,s much Sneering ^f ,„^inmg^oumal.^ JJ, ^y the writer - he to be preferred, lor, as waa y «urvev for 1909,* tnere is featrS TZ^^^^ H.oni» in the UUe Superior region. ABITIBI GROUr. General Charaaer and Subdmmns. has been previously explained. The Abitibi group, as has bee p ^^^ ^^ t^ral and S^SKltSroftS^ave not been wholly ascer- 1 Vol. 92, p. 698. 1911. 1 Page 176. '^ 45 *"i!!f'^" ., j"' ^^^ pu'Pose of description, the complex mav be chforiIicfocV^*^lat^^'^•*''*•'^^ '"^^''^ «°d amphrritS cmontic rocks slate, .erruginous dolomites, and Pontiac series Such information as has been obtained wi h regard to each^f these divisions will be presented in the i olio wing sections Abilibi Volcanics. DISTRIBUTION. throughout the Abitibi volcanics, that it is impracticable to outline the areal extent of these rocks in detail. They constitute the prevailing rock, however, throughout the whole of the northern part of the region, but, except for a smal area of greenstone, between Lake Opasatika and MacLarm creek are replaced in the south by the Cobalt series, the Pontiac serie^ or the southern granite batholith. ' LITHOLOGICAL CHARACTER. General— The rocks included in the Abitibi volcanics ^ «"f '^^"y constituted belong to either the quartz porphy,^: fS«' K^^ ^°"t«-andes.te, the gabbro-basalt or lan^prophyre Sf ^i, f '^ave.undergone such extensive metasomatic alter- atK s that even m their least altered phases little more than hue of the original mineral constituents can, as a rule, bt, c. >d. They are, on the whole, exceedingly fine grained apham ocks, but locally, either in dykes or in the^ centre of a lava flow, become coarse textured and may be ophitic poikihtic, or porphyritic In their fine grained facies the volcanics commonly show spheroidal and amygdaloidal structures, features which are evidently associated with the extenor portions of the lava flows. *!. aS!^?u- ^TP^r^/ a"*^ Rhyolite.— The acidic rocks belonging to the Abitibi volcamcs have been classed as quartz porphyrv or rhyohte, according to their texture. The quartz porphyry U a fine grained, granular rock of pink or grey colour, containing phenocrysts of quartz and feldspar. The rhyolite is also porphyritic, but the phenocrysts are small and are embedded inn'^Jn P*if °V*'° r^*"""- ^* "^^y ^^ P'°J^' K'^y- or black in colour ^dclctidlff'^cturr""'" '" "-^ °"^ °' ^"'"""^ '-*'« Examined under the microscope both the rhyolite and the quartz porphyry are found to consist essentially of pheno- 40591—4} ] 46 ments. The feldspar Pf^« W'Jf ecimens of rhyolite obtained but several exceptionally fr^hspecime ^^^^ examined at the south end of Duparquet lake wer^^^^^^^^ ^^ monoclmic under the m'"""'^"'^;^?^ ?rthe Carlsbad and Manebach laws, feldspar t>yinned accordinj to ^f « ^^^"Jt^i^ed minute spherulitic The matrix o^ ^^'^J^^^h Lidsnar (diameter 04 mm.) but intergrowths of quartz a"^„f J'^J if this was ever present no trace of glass was P'^"*' «^,Sed. Phenocrysts consist- in the rock it hasbeenenturely devitnne ^^^ ^^^^^^^^ ing of tnicrographic intergrowths 01 qua examined. pTesent in «ome of the Jh y,f ^"f eommon^ disseminat^ fhS the'-Sx^o? bir^e rhyolite and the quart. ^'^tnThose locamies wher^^^^^^^^^ SrrarlXgr SaSf ^^^^^ ^^ X^g S chlorite, the relative P'°I^'*7^^°y°uartT porphyry dyke «eatly in different occurrences. A smau Q^ f ^ f ^ ^ *?hich^ntrudes the peenstjne on the^^^^^^^^^^ ^ t lake was found w/'^^.fSeJqSntities of chlorite, s^^^^^^ largely of a carbonate with sm^'« quan .^ ^^ ^^^^^j^ quartz.apatite and rutile. Rhyolite ^ion of sencite on the other hand, contained a large .^jf' borate. The ;?ranged in radial ^Kg^f^t^^J^^^ver Te K«^«"*"y '">''\' unimportant. DiorUe and And.aite.-The ^orite ^f nt^ ?, tX^X'^l volcanics is a grey, green j: pink rock wn^^ ^^^ ^^^^^^ textured but locally becomes veg^ ^^ greenish equivalent of the dionte-the andesite^^ 8 ^^^ alterations erev rock and is usually porpnyntic. yjy^ ^-dividual mineral Sh these rocks ^^ve X^^J^jSeri^^^^^^^^ the aid constituents cannot generally be detern .^ ^^^^ ^^^ tt^slSSartU'd^^^^^^^^ by its greenish yellow ^^he microscopic ^^^Z:{^'l^ ^^^^^^^^^^^^^ of their original composition and o ^ne na^ ^^.^^^ ^^^ ogical changes which ^ave tf en jXe and amphibole, the ^plSocir^wll^S*^^^^^^ '- ''' ^^"""^ " I 47 be recognized haviuR in several cases a maximum extinction angle in sections at right angles to the albite twinning plane of about 7 degrees, probably indicating oligoclase-andcsine. The amphibole may be actmolite, trcmolite, or pale green hornblende and IS evidently of secondary origin. Ilmenite, characterized by ite typical grating structure, is commonly present in considerable quantity, 'n places the dioritcs pass into quartz diorites, the quartz usually occurring in micrographic inter- growth with feldspar. The changes which have occurred in the plagioclase vary greatly from place to place. In Us less altered phases it usually contains innumerable microlites of scricite, but zoisite, epidote, or carbonate are generally present and one or all of these minerals may completely replace the feldspar. Other minerals which occur in the dioritc are sphcne magnetite, and chlorite, the latter being generally abundant as an alteration product resulting, probably, from ferromagnesian minerals originally present in the rock. The andesites are holocrystalline rocks consisting of small phenocrysts of oligoclase-andesine enclosed in a groundmass of minute lath-like crystals of plagioclase (pilotaxitic texture). Chlorite and specks of iron ore are also commonly present. Ihe feldspar phenocrysts are in some places broken and strung out bnearly, a condition which has evidently resulted from the flowage of the lava after the plagioclase had crystallized. Some of the thin sections of the andesite examined contained local areas of quartz and feldspar having the granular appearance of the rhyolitic groundmass. These, in some cases, appear to replace the plagioclase phenocrysts and are, therefore, probably in part, if not entirely, of secondary origin. The alteration products occurring in the andesites, as in the diorites, are epidote sericite, zoisite, carbonate, and chlorite. The following analysis of dacite occurring on the northeast shore of Lake Dufresnoy was supplied the writer by Mr. Stewart J. Lloyd.' ir;^' I90I ffj?' 3-70 E«^ 1-79 £»0. 0-35 ^,f9i 0-58 I^yP 4-82 KjO 1.44 Tio, :.:.:::::::::::::::: o-l? HjO— Q.on H,o+ :.:;::::.:;::::::;:;■■ o-S COj 0-26 98 78 'Abb. Prof, of Chem. and Metal, in the University of Alabama. 48 following norm. .... 33-24 Quartz .. 8-34 Orthoclase 38-77 Albite .. 1.67 Anorthite 9.28 Corundum 1 .50 Hyperethenc 5.35 Magnetite ' ' / o-6l Ilmenite and belongs to: — Persalane Class 1 Britannarc. Order 4 Liparaae. Rang 1 . Liparose. Subrang 3 A specimen of diorite occurnnB on tae - rthe-t^^^^^^^^^^ Dufresnoy was analysed by Mr. i^ioya, ««"^*=" . 49.68 ftiO, .... 15-34 AliOi <•« F«0. »■» FeO 6-»2 CaO <•« M»0 3-84 nSo" If. r&:.:. :;:;:;:;:::::::..•• o-w H,0- 2-" HK)+ O-M ^«' 1^ following norm. .... 12-79 Orthoclase . 32-49 Albite ... 18-07 Anorthite 13-33 Diopside ' ' 11-02 Olivine "... 2-74 Ilmenite ' " ' 6-50 Magnetite '^ who havo ntudied this structure In by th«' numerous ReoloRiBts wno navi^ »v" summurv o( 8, .h :. t^ ."•'*te t - -y ™«^^.,\^jjy of the Lake Superior , >^. ,....., . ;'7yi^-'\«jji\'l,„arizinR the literature on r .biuc. eu> '-t, J^U^uJ^'i'and sut^a^""^' in its develop- «o.d 1 strut u. bo h ^ubag;^^ ^ng of blockB developed mcP t that . ' "^°""^ "?^u "f ^oolina that the development dm ugth.. f.ou a ! -a'»»a'**,'Si°S of'flow and the rate of is. therefore, delcnomed by Ji\"^.^.J/L"entrancr into water cooling, which m ^^--JSiMf^lt-^r^Tf.yonr.i^ suba- quoous origin of the ellipsoidal b^alt." ^^^ formation Dr. Tempest Anderson has rec^tja .^^ ^^^ of pillow structure m % ^f^^ f/,^!^oeT n the Samoan islands, from Matavanu one of tj« ^°'j?^°^Xary corded structure characteristic form of one variety of pillow lava . — Tquart. Jour. Geo. Soc.. Vol. 46. p. 326 1890. .Bun: Dept. of Geo.. Univ. ot C»l., Vol. 1, P- U2, 1893. .^jL Geo. Soo., Vol. 49. p. 211, 1893. .C.S.G.S..Mon.36.pp.l25.1899. . -CharftCteruitics of ExWing Volcmcs, p. 243. 1890. .Quart.Jout.Geo.8oo..Vol.49.p.214,18W- .^^ncicnt Volcano., ot Great Br tain, 'pp. 26. 184. etc.. ISO- Quart. Jour. Geo. Soc., Vol. M. p. 269, 1908. • U 8 O.8., Bull., p. 113, 1902. •Am. Geo.. Vol. 32, p. 78, 1902^ .« Quart. Jour. Geo. Soc., Vol. 64. p. 42, 1908. " Geo. Mag. Vol. 53. p. 262. 1911. » Am. N.Y. Acad. So.. Vol. 20, Pt. 2, PP- W-WT. WW- uolllrt. Jour. Geo. Soc. Load. pp. 631-33. 1910. Geog. Jour. Vol. 39, p. 129. 1912. i(..i 58 ... Accorflinn to A. C. Lawson' the most "tvpiral sph.roidtil ellipsoKlal basalt •«. Ijc found anywhcro occurw in splcinlid i'\\w»- urea in the city o{ Hun Francisco and at many otiior localities in the coast mngcs of (California a4 intrusive rocks." But as far a^ known to the writer, all the occum'nces of ellipsoidal structure which have Iwn descriln-d in California occur either in extrusive rocks or in intrusives elose to their point of extru- sion.' It IS conceivable that tlw ellipsoidal structure miuht originate locally, in dykw or volcanic n.-cks, near their point of extrusion, but the geoloRical relationship and character of the rocks m which it occurs so generally, indicate an extrusive origin and that it is no more probable that th»>so pillow-like forms should be extensively developed in intrusive rocks than the ropy struc ture, vesicular structure, or any other form typical of volcanic lavas. 1 J \\° ^^ u*" ^!}^^ ^"''*** '" ' •■"'•■ ♦Jii'cussion of this subject con- elude that the ellip.soidal s r.ut ire may be subaerial in its devel- opment, although they stai;. that "In the Lake Superior region the interl»ed(ling of ellipsoidal basalts with sediments of suba- aueous ongin . . ,,.,,„,„ to be adequate cvi- dence that the ellipsoidal structure of the Lake Superior baaalts IS largely of subaqueous origin." But as far as known to the wntc't no pillww lavas have been described anywhere in the world which arr positively known to have been solidified under subaer- ial conditions. On the other hand, Geikie concluded after num- T*?",. „ .^'**'^'"* "^ ellipsoidal structure in the British Isles, that all the examples of pillow lav: .:= with which he was familiar were undoubtedly true lavas and belonged to subaqueous erup- tions and a similar conclusion is reached by Dewey* and Flett* in their recent paper on the pillow lavas of Great Britain It seems, therefore, that there is a direct connexion between the elhpsoidal structure and subaqueous extrusion and that the full explanation of this relationship has not yet been given. ,. i^.*'°'°P'^*'' hypothesis in explanation of the development of the ellipsoidal structure mu.st account for (1) the breaking up of the lava into small masses and (2) the assumption of an ellipsoidal form by the masses after they are fonncd. The breaking up of the lavas is probably related to two factors— (a) the rapid cooling of the surface of the flows in contact with the water and (b) the pressure from within the lav,; flows. Dutton in describ- ing the manner in which the pahoehoe structure in the lavas of Hawaii onginates states that "The « nwrficial crust of cooled lava undergoes rupture at numbcrie.ss jwints, and little rivulets onava shoot out under pressure. Preserving their liquidity for 'Min. and Sc. Preas, Vol. 104, p. 199, 1912. ' BullUniv. Cal., Vol. 1, p 202. 1894; pp. 75-103, 1SIB; Vol. 2, pp. 40-SO, 1890. •Quart. Jour. Geo. 8oc., V.>l. 04, p. 269, 1908 w. "w. ^''^^'^ ^^T*^*^-^ •'-"-" ^" Fn. fK J Abitibi volcanics us a result of metamorr' m nil i«^ ?"/P°'*' "^ lithological description, thi^m b^ classified into two groups, the amphibolifc and homb. nd^ s !hi8t, and the sericite schist. '"moi nue AmphibolUe and Hornbletide Schist. —Tho amnhibotitP inH hornblende sch st are grey to dark green or almoT black rc^ks mpillo""^ '"^''*f'« from a fine grained typp containTng IZt toL. -"*" ^''^'"''^ "y^""^' «^ hoTblende, to^'crr^ 4Uo9I — ,) I ! If ■ «0 amphibolite composed of amphibolc crystals half an inch or more in fength. At the west end of Nepawa island, m the contai-t rone of the Lake Abitibi batholith, amphibolite containmg pmk feldspar was observed to occur as dykes intruding the ordinary dark variety of amphibolite, and similar gradational variations may be observed wherever these rocks are found. The microscopic examination of the amphibolite and hornblende schist shows that while they are in general of similar mineralogical composition, within these limits there are wide variations. In some places the rock consists almost entirely Fia. 5. C»mer» lucida drawinn d .mphiboJite occurring on Happy 0«*l~^^'f • rig. »|^2rOpM«Uka. H, hornblende; Q, quarti; C. carbonate; Black, magnetite. Not* the imitorm diatribution oC the carbonate. of ferromagnesian minerals, in other places feldspar is an abund- ant constituent but quartz is absent, or these conditiOM may be reversed the quartz taking the place of the feldspar. The most common ferromagnesian constituent of the rocks is a blue green hornblende, but this is replaced by tremolite and actinoht« in the Opasatika greenstone area. The feldspars range all the way from orthoclase to andesine, but the sodic varieties are most common. In nearly all the thin sections examined carbonate is dissemmated through the rock, filling the interspaces between the other minerals. In addition to the minerals already mentioned, biotite, diopside, epidote, sphene, apatite, pyrite, and garnet are also commonly present. The hornblende schist does not differ from the amphibolites in composition, but has a foliated structure owing to the parallel alignment of rod-like crystals of hornblende. 61 toaet of mAshinir ir. ♦iT* '^^''''^V"^" commonly occur alona when treated with strong acids "'' effervesce freely are fJind" toToSt "S^Lt '^n^T'^'r ''''' «^"^'»*^ «=»>«»« grained mosaic Tauart?\nH 7?"^ °^ an exceedingly fine carbonate and iiZSu ^^InS'^'P''/ throughout which inated. In somLTcUons a f^w hit" "^ "t""*^ "« ^issem- ated fragments of oSart^ AnrfJlM "''''" ""' P'^'^'^'ly «ranul- the oriS rock wi"^rpK?iUc '^^^^^^^^^ '"'^''^''^'^K **^'^^ Of the sericite schists a^c^! iro^o^fdTpSS^^^^^^^^ MODE OF ORIGIN. action of intrusive granite baUiolith« t^ through the contact these rocks occur thevo^^nSiS" if° f^/^y'ocaiity where Chloritic Rocks. DISTRIBUTION. in the re/on "P«««t"'a- They were not observed elsewhere LITHOLOGICAL CHARACTER. ii 62 exrosureH of the chloritic rocks which occur on the north «|J Si of the entrance to Moo«e bay are j^uhar m tb«tm hnth localities the rock is traversed by a network of seams SitaiS a carbonate and chlorite. The rock throughout a ZlSt ^n inch wide on either side of th^.^-J- ^jj^^e^ a change for it stands up conspicuously with a white appearance on the weathered surface (Plate MV). Slale and PhylHte. DIBTBIBUTION. Slate and phyllite were observed in association with the volcanics of theUtibi group in <>"»y ^^ °^»^r;°S>d oH^^^^ shore of Lake Duparquet and at the Clay H>" '»?"* °". *^; S^ievis river. The last named occurrence, however, is in olSproximity to an area of greywacke similar to that of the Siac series and has been included in that formation. Lx- Sngly E pained fissile sericitic schists were observed on ^e S shore of Chauvigny lake on the L*™^'" J* J"^^^^^ n...Hinhamn lake on the south shore of Boundary bay, L.aKe AwSTd if Klaim of the Union Abitibi Minmg Co^y^ which are all possibly of sedimentary ongin and for that reason are mentioned in this section of the report. UTHOLOaiCAL CHABACTEB. Tlie slates and phyllites are grey green or black «)cks, the „,»v Polour beinK due to the presence of carbonate and sencite, theV^n to cSftetaSd the black, to graphite Owing to th« nteS ng of thes^ different f acies, the weathered surface of Ihfr^k h^ commonly a landed appe«anceBcami^^^^^ thin section under the microscope, the slate and PiiyiV*® »[^^^!' o consistTargely of chlorite ^-^^-^^'.^^^'^S^^^^'ttS^ and pyrite, the relative abundance of these minerals varying greatly in the different types. STBDCTUEAl. BELAriONS. Wherever the slate and phyllite occur they have always a vertical or nelry vertical attitude and are enclosed on all sides bv *he Abitibi volcanics. These beds may have either of two nossible re ationships to the volcanics; they may have been aid rvSiontem^ri^usly with the lavas and h^^^^^ intr their ore^nt attitude n company with them, or they may TmSo'Srihan the volcanics and hav^^ their present position. No evidence was oL i »d trom wnicn a 63 Ke^n in; Sat ""^ i^T '" 5° ''^"'-"«='' «' unconformity KSTtLwiSt '^'1 Phylh e and the volcanics it is more prS- thf/xt^sivf/owT" ^''^''''^ '" -™^°™abIe«ucc«»ion;ith ORIGIN. The slate and phyllite contained in the Abitibi croun «« cThrit^'^ »ediment« deposited on the bottom of *Se'^pS! Cambr an sea dunng the mtervals which occurred betw^n «v^ 8ucce«„ve extrusions of submarine lava flows They St to sSSeTr Z'" Jrr^ Y denudation from an an^ciSt land sunace or fine gramed volcanic ejectmenta. althouKh there l« oririi"* tV'^k '^".'^'■' ^i P'^"»' t° indicate a CSSL " ongm. These charactenstics, however, may have been destrm^H by metamorphism. The presence of papwSTn th^ rock Sd dSStioi """""" "'*'™' ""^ «•«« P««ent at the time of Ferrugitmu Ddomile. riAtiPlS'ttl'"*'^ occurrence of ferruginous dolomite in asao- ciation with the volcanic rocks of the older comolex in almoB^ everypart of the Canadian shield where geoloS wo;k hi SS camecTon, and ts probable genetic relattol«hij to The a^SeJTs ?hT»k''7'^ °1 these regions makes this rock of such imporSSce that the fullest possible discussion of its character and Si is ?,^Tt™f^nf?K'' ''*^"?**'^1!' !.^^'«f°'^' ^ made to lirSf the treatment of the subject to the district under description in thi« DISTRIBUTION. Occurrences of ferruginous dolomites similar to those fomid m the Abitibi district have been described in a large nur^! ber of oc^ities throughout the older Pre-Cambrian 3""^? tioi;f "fn^^P"""^-^?^* ?r° ?*«'°«*''«' n^ovi"^- They a^ known to occur m the Lake of the Woods region', on Aird wland m Georgian bay', Lake Timagami', in the viciSity 3 Kenogami lakes m the Larder Lake district', on the shore oi ^orcutK:it^"etr ""*"' '" ^•'^•^^ "'*-'' '^^'' -d '» "h^ Geo._Sorv.. Yol, I, pp. ao, 61, 14S, 1885. 'Can. etween the ferruginous dolomites and quartz porphyry occur- ring m the Larder Lake district was pointed out by the writer m the Summary Report of the Geological Survey for 1909 and the possible derivation of the dolomite from quartz porphyry and^aplite was discussed at some length in the final report on 'Ann. Rep. Ont. Bur. Mines, Vol. 16, Pt. 1, p. 207, 19U. mR that region'. The probable ori|^ of (tome of the {errunnouit dolomite by replacement has been mentioned by W. (5. Miller and A. G. Burrow*', while N. B. Daviuwho amistrd thewnter in field work in the Larder Lake dUtrict haH iuggeiitcd that they have been derived from rock» of the peridotite family*. The derivation of the dolomite occurring in the northern part of the Timiskaming region, from Merpentine and relatetl rocka by carbonatioo and denilicidation, ia scarctly a tenaWw hypothet«i8, for although serpentine ocjcurs in the region, it Ium never been observed aa far as known to the writer, in awociation with the typical dolomite, and except for the presence of carbonate seams in places, shows no evidence of carbonation. Moreover, it is shown on the following page that there is* much evidence which indicates that the chrome mica haH been introdur«>d secondarily into the dolomite, so that the presence of chromium is not an argument in favour of the genesic of the dolomite from ultrabasic chromium bearing rocks. In discuiwing the oripn of the ferruginous dolomites, only two hypotheses need be considered ; they have either been derived from quartz porphyry, aplite, and related rocks by ther- mal replacement or are of sedimentary origin, possibly modified in places by igneous intrusions. The association of the ferruginous dolomite with quarts por- phyry, rbyolite, or aplite has been most striking in every region where the rock has been encountered by the writer. During the autumn of 1911, a return visit was made to the Larder Lake district and a suite of rock chips was collected from a typical hill of ferruginous dolomite occurring on the Harris Maxwell claim. The microscopic examination of thin sections from these chijw showed that all gradations from almost pure dolomite to a rock consisting almost entirely of alkalic plagioclase— albite and oligoclase— and micropennatitic intergrowths of quartz and feldspar, were present and that the dolomite was most abundant in those portions of the hill where the quartz veinlets were most numerous. It was observed in those sections of the aplite in which dolomite was not abundant, that the feldspars were con- torted and broken and showed undulatory extinction indicating that the rock had suffered considerable deformation, and that minute zones of shearing along which chrome mica, sencite. pyrite, rutile, and dolomite were strung out, occurred in some of the sections. In a ridge of ferruginous dolomite which occurs to the north of the Cascade rapids in the Kinojevis nver, a point 50 miles to the northeast of Larder lake, a round mass of similar aplite about 40 feet in diameter occurs completely iurmoir No 17 G«ol. Surv.. Dept. 0* Minn, Cm., p. 23, 1912. "r aip . B« cil&in". oitVVol. 20. Pt. 2. pp. 12-14. 1911. gw. cS.MiI.. iMt.. Vol. U, pp. «72-«8». 1911. 67 ntclowd in dolomitr, and hk«> the dolomite u cut by mimerous veuMi of quarts. The examination of thia roclt under th« naicroBeope showed that the feldspars had been granufaated on theu margin and that forrug.nous carbonate rad garnet had devdoped in these granulate*! zones. Aplite also occurs at a number of pointa on the shore of Fitspatrkk bay, Larder lake, and on the Gold King claim adjacent to the Harris Maxwell, and m all these occurrences is traversed by veins of quarts and dolomite. The asMciation of the ferruginous dolomite with quarts porphyry and rhyolitt- was also observed in numerous oth«T iMaltties in the Larder Lake district. On claim L.M. 31 which lies immediately north of the Harris Maxwell claim on Urder lake, masws of porphyry occur within the dolomite and every stage i« tlie transition from almost pure dolomst*^ to porphyry can !».■ ..hserved. On the Valentino claim in Skew! township, NipisHing dihtrict, a band of dolomite occurs in the midst of quartz porphyry and sends off apophyses into the porphvry along it.H Iwrder, from which it might be inferred that the dolomite has been derived from a dyke which had intruded th<- iKirphyry. In the vicinity of Fortune lake to the northeast of Lak. Opaautika fmnW dykt* of porphyry, intersected by veinlpts of quartz utid iViruKiiiouB dolomite, intrude the Abitibi volcunirs \ll of tlicse (iykew are more or less carbonated and one of them w hen » xaminod und« r the microxrope was found to consist entirely of i rrbonUi , chlorite, wricite, quarts, apatite and rutile. The dolomite which occur.s on the west shore of Eraser lake, in Privat township, contain^ ;* mass of fine grained oilv. looking rhyolite, so that under the hypothesis of therni'iJ replacement rhyolite b presumably the rock from which ';bv dolomite at that point was derived. The association of the dolomite with acidic rocks, ii has also been noted by A.G. Burrows in the Poroupif •• in the following paragraph. "Several samples of ty. ' effervesce strongly with acid show an original igneoM > under the microscope. A sample from near one of th; ( : veins on the southwest quarter of the south half of u 2 n; fifth concession of Tisdale, is a medium grained, greenish, (in. u altered igneous rock. Plagioclase feldspar, showing tO "t " twmnmg, may still be recognized and also micrographic iuo • growths of quartz and feldspar Other examples could be cited of the replacement of igneous rock by carbonate. It is believed that this process has continued in some cases to such an extent that the rock is now largely carbonate while the original rock constituents are largely p!a.,;w, •\viiJv;,', 68 leached out, or so altered as to show little trace of the icneous rock." It has already been pointed out that the chromiferous mica occurs in the aplite along minute shear sones in company with dolomite, sericite, pyrite, and rutUe, a relationship which can best be explained on the assumption that the mineral has been introduced into the aplite in a secondary manner. Similarly, the chrome mica in the veinlets of quarts and dolomite, which intersect the porphyry dykes occurring in the vicinity of Fortune lake, has evidently been brought in along with the vein filling material. Furthermore the microscopic exam- ination of the green dolomite shows the chrome mica to be distributed along lines similar to the zones of shearing in the aplite, so that in this rock also, the mica is probably present as a result of secondary processes. The quartz veinlets traversing the ferruginous dolomite occurring in the vicinity of Fraser lake contain minute crystals of a green mineral which when examined under the microscope was found to be tourmaline (Plate XV). The presence of this mineral has a special significance in that it indicates that the solutions from which the quartz was deposited were thermal and that they contained boron, an element found to be present in the chrome mica. One of the most peculiar features of the ferruginous dolomites are the quartz veinlets which intersect the rock wherever it occurs. Evidence is cited in a later section of the report which indicates that these veinlets have been developed along fractures which resulted from compressive stresses acting in a direction approximately at right angles to the structural trend of the rocks of the region. It is apparent, therefore, that the rock in which the fractures were formed was more competent than the green- stones and slates with which it is associated, but dolomite is one of the least competent of all rocks under conditions of great pressure. This diflSculty is fully explained if it be assumed that the rock undergoing the fracturing was an aplite, quartz porphyry, or similar rock. In summarizing the evidence in favour of the origin of the dolomites by thermal replacement it may be noted: — (1.) That the mineral composition of the dolomite rock is that which commonly results from hydrothermal replacement. (2.) That the dolomite is commonly associated with acidic rocks and that lUl stages in the transformation of these rocks into drlomite has been observed. (3.) That chrome mica occurs in aplite, in quartz porph3rry, and in the dolomite and that there is much evidence which indicates that it has been introduced into all these rocks in a Kpcondary manner. JcU ■- 69 (4.) That the solutiona from which the quarts veinlets were deposited were thermal and contained boron. (6.) That the dolomites are always intersected by quartz vemlets, which indicates that there is a genetic relationship between the quartz and the carbonate. The hypothesis that the dolomitic rocks are of sedimentary ongm rests on their common occurrence in association with sedimentary rocks. Probably the greatest development of ferru- ginous dolomite in the whole of the Timiskaming region occurs in the Larder Lake district where it is interbedded with slates and phyllites and extends in uniform continuous bands for many milw. A similar association has been observed by A.G. Burrows in the Porcupine district as stated in the foUowmg quotation. "In the township of Deloro there are bands of car- Iwnate which are closely associated with bands of iron formation which may be traced for several miles in an east-west direction. The relationship would suggest a similar origin for these rocks, that is, as beds deposited in sea water and now resting in an inclined position dipping to the north. These dolomitic beds are frequently intersected with quartz veinlets, carrying some gold values, hence their importance".' Under the sedimentary hypothesis it would be neccssarv to assume that the aplites had intruded the dolomite and had thereby acquired a large proportion of carbonate. It would not explain, however, the deformation of the aplite and the evident relation of the dolomite, chrome mica, rutile, etc., occurring in the aplite, with this deformation. Nor would it explain the presence of the disseminated chrome mica in the dolomite or the relation of the quartz veinlets to the dolomite. The association of the dolomite with sedimentary rocks is not a fatal objection to their origin by replacement, for the evenly l>edded slates, phyllites, etc., would afford an exceptionally favourable locality for the intrusion of dykes, which might latter undergo replacement. Having stated the evidence for and against these alternative modes of origin, it is concluded that the ferruginous dolomite which is intersected by quartz veinlets and contains chrome mica, has probably in every case originated by thermal replace- ment of aplites, quartz porphyries, rhyolite or other rocks, that the original rock which the dolomite replaced had .suffered deformation as a result of compressive stresses, ana that the fractures formed in this way afforded channels along whii-h solutions containing carbon dioxide, silica, chromium, boron, iron, sulphur, and other elements percolated and thereby cffecteririte, epidotc, garnet, sphene, and apatite. The biotite is generally, in part or entirely, altered to chlorite; the hornblende is also chloritized, in places, but is more commonly quite fresh. I'hc texture of the Pontiac schist is usually fine 72 Brained and the quarts and feldspar as weil as the biotite an.J KTmbUndTcomi^only show an elongation, in the direcUon of Stion (PlateXVIIl), but in places the mica schist passes into Sl^ve phl^ poBsesing a typical granular Jorrfels stm«tu^ AtnvhiboliU.—Eere and there, throughout the Pontiac schist A of amphibolite occur which are «tnkmgly similar to So^ 'contained in the Abitibi group. Tb^V »Jfi^J%*iil^ «een rawsive and schistose rocks of exceedinj^y variame S^«;p mm! anoeareace In some places carbonat* w abundant n tSTr^k ffi ^^^r to a r'usty brown surface m clecp deoiSsicS^lSwe^r^tryoidal-like elevations, a form whirl. sSsThe pillow structure of the Abitibi volcan.cs On ffiy Outlook point on Lake Opasatika a schistose ?mpl"bo»* aS Slaminated with dolomite, the weathering of thi- doSticT^^s giving the surface of t'j^'OS^a.^-ved appear- ance This outcrop occttrs within a few '?** «, "*f J^'^' Kiac schist and £«•, therefore, been classed with the amphibo- ''*"?hf rmphSrof the Pontiac series are such var- iable rocks that it is .scarr*ly possiWe to give^ genera SogJaphical description that will include all types. The r ScrSic examinatKm ^-howod that in some places the amph.- touKSsSTntirely of tremolite or actinolite and <«rbon^e ™i!;u Sn otheTolaces blue green homWemde composed the larjfer Ji^^of tKrsS^oThin sectio^ '"-mined contained u £ge amount of magnetite, other? lamH and one dw^^^^^^ molt common amphibolite consurtjed «rf <1^"*±,?^^ ^^'"'"P*'' hornblende, biotite. magnetite, sphene^nd ^1!^^^^ ^ Greywicke, ArkoK, and Conjtomerolr. -ThenrnthOTpart of thepitecipal area of the Pontiac ^^^Y'fl^^^^'^J Kekeko and Kinojevis lak s, is composed of P^^lt il^a and conglomerate, which extends m an ^t-w^belttavwa ^dthJSbout2miles. Anareaof grer«^ad.e«n*Jtot^^ main belt of the Pontiac series a^^o occurs on the &wjjcv«hvct ax the Clay Hill rapid, and on Clericy lake. Th« rocta w^ ^ CTeenish wev or grey in colour and have all i«n ™ff"^ "^ S^hS ^T^gre^^l^keiseverywl^rerecogni^by*^ pains which it contains. On Clency lake 't r-jf^J^ be interbedded with fine Krained, almost f'f'~_~"r- The arkose is of local extent and differs only from ^''yj'y^t in containing more fragments of acidic f"^^^^^, merate consists of mashed pebBles ^^±^^^^,,^^0 rhyolite, and quartz porphyry m a greywacke maim, pebbles or boulders of basic rocks were s««. ^^^^^ ^r- The microscop c examination of the 8reyw««*e, ar koBe,aSd The matrix of the 'conglomerate shows a^Aes ?° consist of fragments of quartz and feldspar enclo«d m ^ . i.-S 78 a fine grained matrix of simUar minerals along with varyinc propOTtions of chlonte, sericite, carbonate, sphene, iron oxidc' ^i ^^ l"***" ,^^^ »"•* ^VII). The arkose diff^ from the neywacke merely m contaming more feldspar and quartz ?,Sil!^» """T*"*" ."***"*'• The feldspar and Juartz fragments are all greatly corroded on their margins and are E^T»K"''f ^^ recrystallized. The plagioclaslis generally filled with mclusions of sericite and carbonate h^InJS^^^ OFOBiom.-The greywacke, arkose, and conglomerate belonging to the Pontiac senes are uniformly stratified rocks and are evidently wateriain sediments, but do not aflford posiUve evid- ence as .o the mauner ui which they were laid down. The angular- i^^ilf *K f^*i°^i°"'*®'?*' ^^'^ '*« unsorted character would r^ ^!f t " ^ ^^^ deposited at no great distance from Its source of supply, while the presence of coarse conglomerate and the exceedmgly small proportion of fine grained clastic material suggests shallow water deposition, although ripple marks current marks, or other shallow water forms were not observ- ea. It IS possible, however, that these have been obliterated by deformation. From the features observed the greywacke. arkose and conglomerate might have been deposited in a shallow sea.' in a lake, or on the delta or flood-plain of a river. The abundance of quartz and alkalic feldspar and the pebbles of granite, rhyolite and quartz porphyry show that they have been largely derived' from acidic rocks. The mica schist with its associated homblendic facies is believed to have been derived from the arkose and greywacke under the contact action of the intrusive southern batholith the hornblende schist being the result of local variations in the compowtion of the sediments. The bedding-like parting which everywhere characterizes the schist, even where it is lyine honiontaJ (Plate XIX), the alteration of light and dark bantls parallel this partmg, the occurrence of magnetite interiammated with the schist, the homfels structure which it exhibits in places when examined m thin section under the microscope, the apparent cMrformability of the schist in strike and dip to the sedimentary members of the series, and the transition which occurs between the two types of rock, afford ample grounds for this conclusion, the manner m which the greywacke and arkose undergo recry^- taUization can be seen in thin sections of the rocks, all interme- diate vanaticms between the clastic structure and the homfels being exhibited. The various stages in this transformation are shown by photomicrographs on Plates XVI, XVII, XVIII. The mode of origin of the rocks comprising the amphibolito member of the Pontiac scries has not been ascertained, although they possess some charact«ristics from which it might be inferred that they are metamorphosed volcanic flows extruded contem- 74 1 -M»K thi. deoosition of the original sediments, poraneously w^*^?. *''*^rr JZanic oririn for these rockn, 'The features whi^^^^.^Kv to thrampXlites which have ar« their marked ««ilanty to «« a'JP^^ „„ the volcanics resulted from.the «:°'»t'^«=*/f*'°°°\Sn?-; composition which of the Abitibi jpoup. »*"£)*'« r*"**'°"the weathered surface result in P««f" ^^J^W^ struct!^ of the pillow lavas, .omewhat ^^%^'^^^'^^^ZiiT^li^^^^ suggest Two other possible modes of ^8^ '^ metamorphosed, impure themselves, however. Jhey ^|J* ^ metamorphosed intrusive calcareoussediments or th*y mght beme^^^^ objection that rocks. Against the fi^lR^'Xieir observed in association no impure calcareous sedimente were ooserv^^^^^ with the grey wacke, "^'^'^"^a'fe f^^^ t^e Pontiac probably not present '« the wi^al '^'^ J ''« ^ possibility, it Hchist was derived. In oPI>o«'"°\ '^.„'i*Lr,,_„aiirvarY locally i be observed ^^at intmswe r^ks do^t u^^^^ in texture and composition, wherew the wnpn^^^ considerable '"•^.^ Ttv^ sTsL^nft^t hlyhl^u^Srgonecarbona^^^ ;Sort^nh»tr^^ rcSV^s k^rrhlv'e tc^^ inThe vSrcanii'rocks of the Abitibi group. BTRVCTUBAL RELATIONS. fii^ed fi-'^r-rthe^Sclci.st wS ^w^'r the weathered ^^^^^^^^Jil J^if^quStTand feldspar, has origin to ^'^"tf J!?S^^;„ dS;ribing the lithological character already been mentioned in aescnDinB ^^^^^^^^^^ of the schist. In t.iplanation o^ t^e. °"8m oi im b^ it is suggested that the ""'"^J ^''trrS a" o^anyiTg the formed as a result of Btraons in the "cks »• ^^^^ t^eir than the other portions of the rock. already been • .• ^^'^tn tlfe SvS pVs S7the'ioct%ompoi the possess a very marked pwting at intervals oi^^ ^ Sanes parallel to the foliation, which gms "|«^Y,^. Throagh- Sppearance on the weather^ -Hac^g f^aU. ^-X)^^.^ J out the larger part of the P°?,tiac series^ .^ ^^^^^, 7S hold throughout. ^^ ** **•* ''^« relationship may the foSlZl^ii^^til'S::^[^ir bay, Lake Opasatlk.. zontal, but euSwhere in the rl«orA "*'"* ""^ ^'"°''* ^ori- towards the i^wTh (Pla?e XIXi'^LnH K '^ "* '^.^P'^ '°'='««' from the granite bathXhThljt-? •t*'"'''' i" * d.rtction away the trendTthe mign of tlSath^ftrw™'^"^'''?''^'^*^ ri!s?e^5iSt!k^: ''if r^^^^^^^^^ wostof PapftSaL If r^^*'''""*'*"^^* '" *»'*' district foliation and Sdfng are Ural el TT^^ **'''''^°'""' »'^''* *»>« PontfafiriS £ S^^Ah'^?'?"""!"-''* '-Shin of the 4Ki»iK. ,,^ • ™P""- *'. ^f*^ rontiac series itt vouneer than thp Ahjtibi volcanics, some evidence of iinr.nn<«r™u„ 1 II • • oT r-^si •Cii'-Tri 3t ~"S 76 the «'"««*PL"l"^'y"Sf however^ have under^ne w many the north. . T*'.?*'.'**^^^ EevWence alone is ln»ufficient for structural viciMitudes that thisev^encea^^^^^ ^ ^.^p,y ^^^. poflitive concluBiona and must oe iuh sefltive. * .u„ Pnnfmr scries to the younger rocki* TherelationKh.pofthePontmr«ew^^^ ^ „ o( the region w d'«'U«^d in^a^r^i^ on ^^^^^ ^ .^ ^^ ther«fore,be8iniply«tat^heTetnaiu ^ ^^.^^ ^^^^j ,^ itn.'iM. is overlain uncimformably ny »"« ?Ill by dykes of the Nipin^mg diabase. THIOiNESS. ,„ discussing folding in the rocjj of the^^^^^ i. Has pointed out that they apparently^^^^^ succession diPP>«K *?*"tlelLt 45° If a geological section b,- minimum average being aj »ea«t « • ^;,^/,trike along C'aron measured in a direction t^nsver^ t« in ^^^ ^^^^^^ lake, Lake Kmojevis ,'*"4 ."'' * ^j ^Ues, and a minimum wou d have a horizontal width "^{"'Xi^at there has been averagedipof 4J Assgiing-^t^^^^^^^^ ^^ ,, no duplication of beds «y J'?'"^* . .v.^ Pontiac series has a foliation and beddmK a^ e^n"^^* J Ssand feet of this, thickness of at least 37,000 feet. »evt however, consists of amphibolite. COBRBLATION. The P-tiac seric. «t »-f «;!J5!][ JSL^lfjJSdTn of the major «ib«i»^"'°°f J^ivalent of th other regions. I^^^y »^ *''^!,'^X Coba t •^"*"''*' ^'^^ ^*''' " as the Timiskammg senea m tl^Co^^^^^^^ merely con ecture. It is very P?«!'*Jf^;7„ the Lake Superior of the rocks classed »» '°*f^,S by granites. There are region, since these are i^^o mtjuded ^y ^^^^^iac series and also many points of similwity between in ^ theCoutchichingseriesd^cnbed by Law^^^^^ ^^^^^^ ^^^^^ -ffdi^Sn%t^o?iro»^^^ basis for .ondation. Granite and Gneiss. DIBTBIBUTION. U 1.; 77 part of the arra is occupied by granite and gneiw. but thin is merely a iimall marginal portion of a huge complex of acidi.- rock, which extendH far to the southward. 8in^ thi° iS f oecurs m the southern part of the district it will be refei^.. a« the southern batholfth. There an. fourMall„ iShSuh " mam.s m the northern part of the region, one of which S-cum on Lake Dufault, another in the vicinity of Robertson lake i third to the northeast of Oauvin lake, and a fourth in trvicSit; o Lake Abitibi. The Lake Dufault batholith has a dhunS 3 aljout 4 miles and that on Robertson lake 10 miles; theCJauv n d "r an^d\t''Ahvr- Tl A'!^*'"^' T^P* °° '^ -uthwifl^r- der, Md the Abitibi batholith extends over the interprovincial boundary into Ontario, but according to a map by Mr MB •ibout 14 miles m length. A few very local intrusions of aeidir rocks also occur on Hub lake, on the La Sarre river, on Makamik lake, and in other localities. wianamiK LITHOIOOICAL CHARACTER. The rocks uiduded in the batholithic subdivision of the older complex are medium to coarse grained, granular rocks S'lf "V^^l^^y ^''L*^°'• P'"*' •" '•°'o". l>«t in some of the smaller bathoiths and local intrusions are so very dark that they would never be recognized as granites in the hand cS^?iT„*°'i-*n"^^ ^'''- the abundant quartz which they tontam. This dark colour is not due to the presence of abundant il^^l^T^ minerals but to the metasomatic alterati^s whch the feldspar have undergone. In the southern batholith botite granite is the aominant rock type, but in smaller northern massives, hornblende is more common and usually occurs in a^L"^'*^ i*>L^'°*'^-.. ^^^ hornblende and biotite L^y locally show a slight parallelism in their arrangement, but a m^ iiounced gneissoid structure is not extensively developed excwt m the northern extension of the southern batholith which occurs between Atikameg bay, Lake Opasatika, and Wijwaug lake. The granite is not generally porphyritic. but in a few places phenocrysts of feldspar were obser ,, d. The Robertson Lake batholith contains large pseudo-phenocrysts of quSt/ a half inch or more in diameter. 'Juan/ Aplite and pegmatite dykes are very common in all thesf TKil "* are especially abumlnnt in the southern bathS Ihese are pink or white rocks which are niineralogicaliy ident cal m composition consisting almost entirely of quartz. felTS ^hl«"'fK'^'^'*'"Vl^''^P"**^*^'**'"fi"'^ grained felsitic textile whereas the pegmatite is very coarse containing feldspar cmtSs 40591 — 6| -t ; 7S up lodincbMm length ■ »n'«'»y''^ p^ntijc series »nd in th.- notably in the contact «one with JJ«^*^ , pefin*tite occur rdSelel'Tt^mLn^ Thl'n..^ ^«> occur, .n plactT^uliar ro«ette-Ukc ^J^*^- ,^ ^.^ing an r«^m- ination of an «P««"'«i°* ^„^'* .j";: very Uttlo biotit* may be «een In Home placeH, a granite cent .ming very mv .^ ^^,,^ to cut acroHH anothtr KJ,^^^^ '^ *7ut a hornblende Kt.uite abundant, or a »"«^'»-,« .^'"^t^^onlybng »chU.ren of granite in a Himilar »<»"""• J." ,7, th, r^k may huv. a ban -ed appear- rich in biotite are !)re;«'nt or th. "^"^ "^^ j y^^^^^^^. Local arcaH ance owing to vun vtum« m \;;,„XSt but the«e are probably of hornblendii.; a'\»'^" ''""jT^he" into the magma dunng related to.outs.cl.rock« win.;;. > -vo W^^^^^^^ .^ ^^^ ^^^.^^ „„ its intrusion «» » J'"* *rVo oAut formations, the n-lation of the F'^""* vL«, n <,i the granite and gncwn The microscopic :'X»"^""i'^" '^( ii%niniteH?rfvniVegnci8s „how« them to be ^yP'^-l*' '"^"^Siinl biotite or lK,th family. '^"T^'"'' Ji^'^UaL Spar -orth-Hla^e. micro- thcrte rocmltrs with alkaiic '"" A. w place i he hornblende dine, and ull;.ie-und niiam. " ^i^y.UeH.orevendioriteH varieties pas- into granoaiont^''^u^^^^^^ j^^^ ^j^^^ by the disappearance of pot.s!,eld«^^^^^^ ^. ^^,, occurrences are of local *;''*'^".^-*",,^,.„vite. apatite, sphcne, occurring in the gramte and pte... are mu. o e^^ ^ J,uu,rite, ..pidot<.,allanite. m'^^»c^•tf.»™2w^^ hornblende or tSe latter Mng always ?^ ^'^?fMlv^X<^^^AeTgoae.mt■ia• MU.. In thos.> places where the ^^^^^^ into%ricite or «omatic alteration, they a'^ .""^^f^.^piite and pcRmatite when toHcricite. ^^^'^''''''}'^Xt^l\^ZtoZs\,^i chiefly of quart.. ..xaminedmicroscopual^ were found to con ^^^^^^^ Sy "£e-i"S;S ^itS'^ wore magnetite, biotite. calcite, and garnet. BTRUCTURAI. UKLATIONS It is pointe aiwumed, therefore, that nil the granite and gneim belonged originally to one great magma mtum and that the outcropK of granite and gnei»s o«rurring in th«' region are Dimply portionM of the larger hatholith whieh have p«>netrated to a higher elevation than the main moHitif. The oeeurrence of pebbles and bouldern of granite in the tonglomeri»te of the Pontiac Heries, however, Hhown that granites of different ages are present m the region ho that the conditionH may lie more complex than this aw*umption implies. The striking local variability in the granit*' and gn/jH pomted out in describing their lithulogical eharaeter is evidently due to two djumetricaily oppiwite eauHes, one that of aiwimil- ation by which fragments of exUrnul rocks have sunk i.ito the magma and have l)een partially reerystalliml, ami theoth.-r that of difTirentiation by which an originally homogem-ou- magma has resolved itself into rocks of different compoaition but It IS not always possible to ascertain which of t he two processes has iH-en o|)«'rative. Many of the local areas rich in ferromag- nesian minerals, as will be shown laU-r, are evitlently derived from the Abitibi volcanics, or in the case of the southern batholith from the amphibolites of the Pontiac series. It is probable, on the other hand, that the schlieren of biotite granite are the result of differentiation, although in the «nal stages of assim- ilation a product of this type might result and Ih> strung out i!"*''*r« ^ movements in the magma. Th«' larger part of the differentiation in the granite ami gneiss, however, is of a type which might be descrilied as differentiation by solidification. In those places where, locally, granites of slightly different com- position cut across one another, it is «'vident that the intruded portions must have been at least partially solidifietl at the time the intrusion occurred. This phenomenon, therefore, probably owes its origin to movements in the magma during solidificatioti which caused the solidified poitions to break up, the fractures being immediately filled with magma of slightly different, composition. The formation of the pi'gmatites and aplites IS another example of differentiation accompanying solidifi- cation, the final stages of consolidation l)eing accompanied by the evolution of juvenile gaseous solutions from which the aplite and pegmatite were deposited. Relation to the Abitibi Volcanic Complex.— The intrusive relationship of the granite and gneiss to the volcanics of the Abitibi group is apparent not only from the occurrence of num- erous dykes of granite, aplite, and pegmatite in the surrounding rocks but from the contact metamorphism which they have produced. The greenstones in the vicinity of the granite have been transformed into amphibolite, hornblende schist, and sen- MIOOCOfY RBOIUTION TiST CHART (ANSI ond ISO TEST CHART No. 2) bi 12^ |Z5 |M ■" ■■■ u iSi ■ 2.2 ^1^ mil ? 1^ 1^ Li ■■1 1.8 1.6 ^ APPLIED IM/1GE In ^^« '6SJ Eost Mom Street --|^g Rochester. New York t*609 u-U ^jg f^l6) 482 - OJOO - Phone ^^ ^S (7'6) 288- 5989 -Fa» '»r h h 80 cite »hi«, th, rt* oi ^ '*»SiSt' StoS'fhj; z contact is mied with inclusion8(Plate XX) of th^^^^ These rock fragments have t«e° evide^Uy stojja o^ .^^ magma probably as a ^^^^^^^^^^^^ ,^^^^^^ it cess of assimilation. „nn„tTv rock in the graniie . p,^rxsnz^33ra..u.^S- contact were no doubt de**^^^ ;'°^^;;e q^^^ of the solidation and may have been ^e J because of th«™ partially consolidated P^*^ b"* ^^^L luid E qSities of intrusion when the magma ^^^. ^8^^ ^^^en K the batho- the Abitibi volcanics may possibly "^y^^^^^Sgnotavail- liths, but positive 8e«lX'rlf7rf t'Lat ffia^^^^^^ °* able. It IS concluded, tt'e'^;°y^' ^.Y^.^^^^^^ the Abitibi group granite and gneiss which '^t^^^i^^^^Sbv lifting and thrust- made room for themselves m two ways . ^ bj m«ng ^^^ ing aside thesurroundmg rocks £)by^^^^^^ fncidental whether the latter was of great importance or ouijr » roScSesTSrif^S; e^rth^ughout^t^^^^^^ in the .vicinity rfth^i^ contact J^^^^f ^J^f ^^^^ along their pP'^fwSn^ which HwTimissible to differentiate the line of junction in '^nicn it «» »~ . ^j^ ^^ granite *'° *TtfKled ^^th^SSmeSurSllo'iS ^' the F^ontiac appears to be failed ^^°. V^j" ^^ ^y dykes of pegmatite and ^?r "^rollrdvkerin sS K bling fau^d.along the over 4 miles wide, m which dykes ana irregma increasing in aplite, and pegmatite "J^^.^e the Ponjac s^ -, mc g^^ 81 showing that they have not been tilted ^ut of their original positions. In the country to the west of Lake Opasatika, the manner of intrusion was somewhat similar to that just described, but the dykes were narrow and penetrated the schist parallel the Rchistosity at intervals of a few inches or less, a phenomenon generally described as lit par lit injection. Throughout the contact belt to the east of Lake Opasatika, small local areas of rocks rich in ferromagnesian minerals are very common. In some places, these consist largely of horn- blende, in others of diopside or of hornblende and diopside together, but generally varying proportions of biotite, feldspar, and quartz are present as well as the less abundant minerals apatite, sphene, magnetite, garnet, epidote, pyrite, and calcite. These masses were never observed to have sharply defined contacts with the granite, yet from their similarity in composi- tion to the contact metamorphic phases of the Abitibi volcanics and the amphibolites of the Pontiac series, it would seem most probable that they are recrystallized and partially assimilated masses of external rocks rather than masses (autoliths) which have segregated from the magma hy differentiation. Beyond the contact zone to the north, local intrusive masses and dykes of granite and related rocks are very common through- out the Pontiac series, some of which seem to have been broken up by deformation so as to simulate a conglomerate. A photo- graph of some of this autoclastic rock occurring on the east ^ihore of Kinojevis lake is shown in Plate XXI. It has already been noted, that the Pontiac series dips away from the margin of the southern batholith at a steep angle and that these sediments have been rendered schistose under the contact action of the granite and gneiss. It is, therefore, inferred that this batholith was also enabled to reach its present position, in part at least, as a result of the uplift of the overlying and sur- rounding rocks. This uplift, while brought about directly by the batholith, is, no doubt, indirectly related to the mountain making movements of whinh the intrusion of the batholith was simply an incident. To what extent subcrustal stoping was a factor in the opening of the magma chamber of the batholith is imknown, but the relationship of the Pontiac series to the gran- ite in the vicinity of Caron lake and west of Lake Opasatika, suggests that these rocks had a specific gravity which was not much in excess of that of the magma and that stoping was unim- portant as far as this series was concerned. It may have been a factor, however, as regards the amphibolites and any volcanics which may overlie the Pontiac series. fl 82 Relations to Younger Formations.— The relationship of the oranite aLd gSeisB to the Cobalt series and the Nipissmg diaW iHisSed later in the report. It may, therefore, be rimpb^ stated here that the granite and paeiss are ovejlam uncoirformably by the former and are mtruded by dykes ot the latter. HODE OF ORIQIN. The mode of origin of the granite and gneiss has already been state" or implied in various sections of the report a^d need only be summarized in this subd- vision, /{fy. "^. f ^ich to form portions of immense, deep «eated bath"! ths which Svaded the rocks of the Pontiac series r>.nd the Abitibi group M an accompaniment of mountain making movements. The SetSrsSSy show no evidence of granulation, undiJatory ^Stion or other evidence of deformation, were probably fomS Ma result of pressure in the magma during their con- sSSon. The apiit^s, pegmatites, and granites which cut one Sier are believed, as has already been explained, to be due TdifferSation by 'solidification, while certain other k,^al variations rich in ferromagnesian minerals aJ^.^^'^®?. *9 i""^! originated by the recrystallization and partial assimilation of Sded rocks which hLi fallen or floated into the magma. AGE .i.ND CORRELATION. The Kranite and gneiss of this region occur on the northern border of ^immen^ complex of acidic rocks which extend SSully along the whole of the southern Part of th^La^^^^ entian plateau from Georgian bay to the Gulf of St- La^en^«- These Kranitic rocks have been generally classed as Laurentian folSThe nomenclature adopted by Sir W'^am Logan Mid the roclS of this district, accordmg to th«?nP^al classification should also, no doubt, be called Laurentian. In the Lake Superior region, however, two granites are recognized, the JoSer of ?hich is classed as Po^^o^er Huroniana^d since there were also at least two gramtes originally present m the AbTibrdistrict, aa shown by the pebbles and bodders of granite 1^ the Pontiac series, the question arises whether the granite and gneiss here described is not, in reality, the eqmvalent of the y^Tger post-Lower Huronian granite of the Lake Supeno reirion In view of these complications in the nomenclature hM been thought advisable to omit the term Laurentian in 83 describing these rocks. As far as was observed they are intru- sive into all the surficial rocks of the older complex, but are ov-.. lain with striking unconformity by the Cobalt series. The above 8t..tement mcludes all that is positively known with reeard to their age. ^ Coball Series. GENERAL CHARACTER AND SUBDIVISIONS. In this district as well as throughout the Timiskaming region generally, the disturbed and metamorphosed rocks of the older complex are overlain by a slightly deformed series of clastic sediments, conglomerate, greywacke, argillite', arkose, and quartzite. These rocks are not sharply defined members, for they not only pass gradationally into one another, both horizon- tally and vertically, but patches of conglomerate commonly occur in the midst of greywacke, or greywacke in the midst of conglo- merate, and similar relationship may exist between all the mem- bers of the series. Nevertheless, in a general way, there is a suc- cession in most localities, from a basal conglomerate through greywacke and argillite to arkose, which in turn is overlain by an upper conglomerate. A compilation of all the published observations of the succession and thickness of the various rocks comprising the series throughout the Timiskaming region is given in the accom- panying table. Many of these sections are evidently only partial, including in some cases upper members and in others, the middle or lower. It can be seen, however, that there is generally an upper and lower conglomerate with greywacke and argillite, quartzite and arkose as intermediate members. a^'J^t^^""""^ f PT-.^- V- Pireson, the term u^Iite U here re■» •» tbe mud-slatc scries corresponds verj clowly to that of quartiite u the aand-eandstone group. "—njr iw 84 I SECTIONS or TBK COBALT 8BBIBS IN THB TWIISKASIIJiU SECTIONS "J^^^j^jj^ ONTABIO AND QUEBKC.' ' (Soetiona are in descending order.) Rock. Thick- ne»8. QuartziU', etc ■• • Sliitc and urey wacke. . C'onglonierute Slate* Conglomerate., Conglomerate. QuarUite Quartiiti'. etc Slate* and grcyw !kc.. Feet. 1,100 100 000 Localiiy. Reference. Timiskaming di»- Bctwccn Rabbit and Timagami lakea. Cobalt, Ont... 90 90 Conglomerate | jOO Quart itc 1 ."? ylatc* •»" Conglomerate J Quartzite ! ^ Grcywaekc I ^ Conglomerate I Conglomerate. . Quartzite Slate* Quartiite Conglomerate. Windigo lake.. Mount ShiminiH.. Cobalt, Ont., A. E. Barlow, Rep. Can. Oeo. Surv., Vol. 10, p. 10«, 1897. G. A. Young, Sum. Rep. Can. Geo. Surv., p. 198, 1904. W. A. Parka, Sum. Rep. Can. Geo. Surv., p. 211, 1904. W. A. Parki), Sum. Rep. Can. Geo. Sunr., p. 21S, 1904. W. A. Parks, Sum. Rep. Can. Goo. Surv., p. 220, 1904. W. G. Miller, Ann. Rep. Bur. Mines, Ont., Pt. 2, p. 34, 1906. Conglomerate Grey wacke and slate*. Slate* Quartzite Conglomerate. Conglomerate. Slate* Conglomerate, etc Grey wacke quartzite., Conglomerate Larder lake, Ont. R. W. Brock, Ann. Rep. Bur. Mines, Ont.. p. 211, 1907. A. G. Burrows, Ann. Hep. Bur. Mines, Ont., Pt. 2, p. 24, 1908. Claims H.R. 34 j and 163 South E^fi^U^kcGow- A. G. Burrows, Ann. Rep. Bur. Greywackc, arkose, etc . Conglomerate 7 ? 200+ 7 7 ganda dist. Bloom lake Gowgandadiat.. Montreal River dis- trict. Mines, Ont., Pt. 2, p. 10, 1908. A. G. Burrows, Ann. Rep. Bur. Mines, Ont., Pt. 2, p. 10, 1908. W. H. Collins, Prelim. Rep. on Gowganda Dist., pp. 26 and 27, Geo. Surv., Dept. of Mines, Can., 1909. „ ^ W. H. Collins, Sum. Rep. Geo. Surv., Dept. of Mines, p. 199, 1 1910. "*The term slate is used for a slate-like rock without slaty cleavage, anpllit*. See Dace 83. DISTRIBUTION. The Cobal series is extensively developed in only two parts of the district; only one small isolated outcrop was seen elsewhere but it is probable that other similar occurrences are Present which were not observed. The greatest development of the series is in the hills which occur to the west and east of the north end of Lake Opasatika. All the prominent elevations of this i 85 diatrict, the Labyrinth hills, Mount Shiminis, the Swinging hills, and the Kekeko hills are composed of these rocks, and constitute remnants which rise above the general level of the surrounding rocks of the older complex. A second large area of the Cobalt series occurs along th'2 height of land north cf Bellefeuille and Dufresnoy lakes. Unlike the southern area, the series is re- presented, here, solely by conglomerate which forms very low hills of no topographic prominence. The full extent of the Cobalt series in this locality has not been determined, but it must cover a large number of square miles, for numerous glacial erratics of conglomerate, some of which are as much as 30 feet in diameter, were observed throughout the country to the southward. There is also a small outlier of conglomerate on the Labyrinth river which is, however, only a few feet in extent, the surrounding rocks belonging to the Abitibi volcanics. LITHOLOQICAL CHARACTER. Basal Conglotnerale. — Wherever the Cobalt series was seen in contact with the rocks of the older complex, the basal mem- ber of the series was always a conglomerate. The outstanding feature of this basal conglomerate is its heterogeneity, not only in the size and angularity of the included fragments, but in the variability of the rock, both in texture and composition, from point to point. In some places the conglomerate is largely composed of coarse fragmental material with little matrix and in other places consists largely of matrix with few fragments. As a rule the rock is unstratified, but in places, a partial align- ment of the pebbles can be seen. The matrix of the conglomerate varies greatly in texture and composition and may be either coarse and feldspathic or exceedingly fine grained and slate-like in appearance; the coarser types are, however, by far the most common. Examined under the microscope the matrix is seen to be composed of angular, subangular, and round fragments of quartz, feldspar, quartz porphyry, mica schist, rhyolite, andesite, basalt, and other rocks belonging to the older complex, which are enclosed in a cement consisting chiefly of chlorite but usually accompanied by small quantities of carbonate, epidote, and pyrite. The pebbles and boulders of th?' con- 'omerate i^^clude, even in a single rock exposure, nearly every v iety of rock occurring in the older complex. Fragments of grmerate Arkow ♦ Abitibi group. Conglomerate Arkose Greywacke argiUite Owing to the general absence of exposures on the low slopes of nearly all the hills of the region, the sections are generally incomplete, but sufficient information has been obtained to show that the usual succession found in other parts of the Timiskaming region is generally represented. The excessive thickness of conglomerate occurring in the Kekeko hills differs from the more typical basal conglomerate in the large proportion of arkose which it contains, and in this respect, as will be pointed out in the section on the origin of the Cobalt series, is strikingly similar to the fluvio-glacial deposits of the Pleistocene. It may also be observed that the thickness of the various members varies greatly and that at the north end of Lake Opasatika, the grey- wacke-argillite member is entirely absent. This feature is a characteristic which commonly belongs to terrestrial deposits and is in perfect harmony with the hypothesis advanced later in the report that all of these rocks are closely related in their origin to continental glaciation. STRUCTURAL FKATURES. Folding. — Since the conglomerates of the Cobalt series are usually unstratified and are never uniformly bedded the attitude V 88 of these rockB cai only be wccrtained from the ntrikc and dip« of ?L «^v^cke uTKiUite and aikose.but from a large number of the greywiwlie, arpiiii* « . .^^ j^^^ ^^^^ ^^y Txed trJiri' d:^°) inti lold. tpUng in . direction "' -Kbn^t?rpS.saThat^^^^^^ „f »h« rS serie could have escaped deformation by faultmg '^"'Ll/fon (X Older Compkx.-It has already »M«en explained ♦hfl reirion was reduced to almost a peneplain. Ihis <^ro8ion iSteS was finally terminated by the deposition of the Cobalt "*"%« contact between the Cobalt series and the rocks of the Lnwaidint^the basal conglomerate; in other places, however, ?frc"ntlct is very sharnly'defined. the ^o-f ^^^/'^Jf^^^^^^^^^^^ a smoothly denuded surface ExampU -^ of the transit on^ tinnshin ci n be seen at the north end of Lake upasaiiKa, on me soTh SioS ot Nissaki lake, and a^^^^K *he /xo:t'iwest «ho^^^^^^^ Renauld lake on the road to the property of the Union Abitihi MiSS Company At the first two occurrences the cong omer- ate o^lrShe Pontiac schist, and at the third, the Abitil.i vol- fanics The sharply defined contacts were observed at a point Xut 1 mile south of Kennedy lake, on the east "de of the large iSd in Difay (Rest) lake, and on the Bouth «hore '>* ^l^^Ke Where the contact s exposed on the island in U. j*'^®.*"^ Smer'ate lies on a flat.surface of P""^^ «^,^^^^^^^^^ dykes of granite have been injected parallel to t^« scbwtoMty. in botTthe ..her localities the consl^^^te^^^^^^^^ eroded granite, the surface exposed on the south shore ot uuiay lake having a slope towards the north. ORIGIN OF THE COBALT SERIES. Introductory.— The assemblage of clastic sediments com- prising the cZlt series has in recent years ^«theobectof sSl study by those geologists engaged in field work m the SskaSg region for the purpose of pro,uring evidence which 80 would confirm or disprove the ilocial hypotbcsiH which han been strongly advocated by Dr. Coleman in a number of recent publications.' With this object in view, the writer, while in the field, paid special attention to those characteristics of the various members of the series which might have bearing on the conditions under which they were deposited, hoping in that way to reach some definite coneluHions as to their origin. That the conditions under which the tenes was deposited were unusual is indicated by the various modes of origin which I. Ave been suggested from time to time, by the geologists who have studied these rocks in the field. Owing to the fact that the earlier geologists did not distinguish the Cobalt series from the underlying Abitibi group (Kcewatin), the conglomerate was thought to be closely related to the lavas of the underlying base- ment and were said to be of pyroclastic origin,' although it w ts noted that many fragments of granite and other plutonic rocks were present. In 1905, Dr. A. P. Coleman, in his report' on the Sudbury nickel field, pointed out the resemblance of a greywacke conglomerate, occurring in the vicinity of Hamsay lake, to boulder clay; and in the same year. Dr. W. G. Miller mentioned the pos- sibility of a glacial origin for the conglomerate of the Cobalt series, but also suggested desert conditions of deposition in the following quotation. "The writer is not able to offer a satis- factory explanation for the chiiracter of the sediments found in some of these strata To account for the unde- composed and angular character of much of the fragmental material, the writer is inclined to the belief that desert condi- tions prevailed in this region at the time some of the middle Huronian rocks at least were formed."* Mr. R. W. Brock in his report on the Larder Lake district published in 1907,' noted some characteristics of the rocks favourable to the glacial hypo- thesis but concluded that there were still difficulties in the way of itp acceptance. He also observed that many of the included fragments had the form of boulders worn by river sands. Application of Criteria. — Although the various suggestions in the above quotations all imply a continental origin, none of these writers have pointed out the many characteristics of the series which point to terrestial conditions of deposition. The great heterogeneity and general absence of complete sorting throughout the greater part of the series, the ^jresence of ripple marks, current marks, cross bedding and interformational uncon- ■Ain. Jour. Se., Vol. 23, pp. 187-192. Bull. Geo. Soo. Am., Vol. 19, pp. 347-oM. Jour, of Geo., Vol. IS, pp. 149-1S8. 'Ann. Rep., Caa. Geo. Surv., Vol. X, p. 98, 1897. 'Ann. Rep., Bu.- Mines. Ont., Vol. 14, Pt. 3, p. 129, IMS. •Ann. Rep., Bur. of Mines. Ont., Pt. 2, p. 41, 190S. • Ann. Rep. Bur. of Mines, Ont., Vol. 10, p. 212, 1907. m I w lonnitiet, the pretence of ui ancient •oil at the bwe of the iSomerate in place., the angularitjr or •ub«ar»»"'ty ^[f^ fnumenUl material compownf the wnee, and the ir^J »Wcli- neMTand enormoiw extent of the conglomerate are feature* distinctly characterUtic of land sediment.. "*'";, *J{fl^ be awumed without further diwuMiion that the Cobalt wsne. i. of terre.trial origin, the term termitnal implying deposit on on the land in contrast with deposition m the Ma or on the """cwtincntal elastic sediments may be formed by volcamc action or by weathering, creepage, l»ke«,nvers, winds or j^iers, the degree of importance and relationship of the latter agencies to one another depending, in part, on climate, and m part, on the ***'~lirfhe^foltowlnrd>9c ission some of the criteria which char- acterize wdiments originating in these various ways will be ap- plied to the different members of the Cobalt series and in that way an attempt made to reach some conclusions a. to the climate and conditions of deposition prevailing during this Huroman '^"(l) Pvroclastic Origin.— Owing to a misunderstanding of the true relationship of the Huronianof t.>e Timiskaming region to the vScanic rocks of the older complex, the conglomerate of the Cobalt series was at one time thought to be of Py«>c "tie origin, but it is now known that it is a.raost ?* ««* «»t»J^iy^ composed of material derived from the underiymg floor. Thi. mode of origin need not, therefore, be considered. (2.) Weathering and Creepage.-Smce weathering «md creepage are closely related processes operatmg together, lor the Dispose of this discussion they may be considered as one. The indefinite contacts which occur at the base of tne Cobalt series in places, indicate that at the time th« deposition of the series was initiated, the surface of the ««»"fnV.^^t»r^ covered Ly a considerable thickness of soil and that this has been preserved so that the basal beds of the conglomerate at these points represent a fossil regolith, developed in situ by weathering •^ This ancient soil consisted of disaggregated undecomposed rock fragments, a feature from which some inferences may be drawn aito the climate prevailing at the time it was formed. The domination of disintegration over chemical decomposition on the earth's surface to-day, is characteristic o^'ePO"*' f, youthful topography, is also characteristic of and climates ll8— M, J., Jour, ot Geo.. Vol. 18, p. IM. '«»• . ■ : A. Amer. Jour. 8ci., Vol. 19. P- l". »«<». Rep.. Bur. Mines, Pt. 2, p. «, lOM. •Willi., b'!. Jour, of Geo.. Vol. 1. p. 477, 1810. •Pumpelly, E., Geo. 8oc. Am., Vol. 16, p^fl7. IMS. Barren, J., Jour. Geo., Vol. 16, p. 167, 1008. »1 and to a W extent of cold or temperate climateH', but in not nwhf tfiH^^i?^ *•."" ''r'** V"'"'*^''*'' ^'"<- 'hiH region, at the time the soil wa8 formwl, wa« pra< licully a peneplain fc«?'^.1P'!" J''"*"^ "»"y '.'« •"'"inated, If ft be'iLumr" therefore, that the variationn m the conditionn for Hoil .levelop- ,T« ♦**"^- K* "'""I ? f't-ramhrian time «.. at present, the e mate which pm^eded the deponition of the ( Wt series wa» either cold and humid, temperate and humid, or arid It 18 powtible that owing to the abwnce of abundant vege- tation to supply irbon dioxide to the ground water or because or differences in t.. j composition of the atmosphere, the relation- ship of the chemical decay in the soil to climate may have been somewhat different at that early perioa, Lut it is doubtful whether this would be of sufficient importance to r-'if, the foregoing conclusion. ' The abundance of limestone in some of t' , , , ,y Pre- «.aml>rian formations indicates that carbon dioxide ■ ertainlv present in the atmosphere at the very beginning o. geological time and may have been more abundant than in later periods for It seems probable that the loss of carbon dioxide from the atmosphere through the formation of limestone and coal beds since the PrcCambrian has been greater than the additions irom other sources. (3.) Lacustrine Deposifon.— The uniformly stratified argiiute, greywaci.", arkose, and quartiite which form a consid- erable part of the Cobalt series were evidently deposited from standing bodies of water and are, therefore, flood-plain or lacus- tnne deposits. However, from the general greenish grey or green colour of all these sediments, from the absence as far as has been observed of mud cracks, rain prints, or other evidence ot exposure to the air,» in even the fine grained argillite, and from ttic presence of continuous ripple marks in the quartzite it seems safe to conclude that t -se Hepos. i have not been laid down from either flooded r\\ or ephemeral lakes but were deposited from permanent L es of water which persisted frou year to year. With regard to the characteristics of these sediments which have a chmatic «.gnificance, it may be observed from the leatures ni«>ntioned L. th.. previous paragraph, that these, in general, point to a humul rather than arid or semi-arid condition of deposit . Furthermore, boulders occur in places in the ' ??*.','• '• ^- B""- *2, U.a.G.a.. p. 12, 1888. • HiSSSd! e; wv. is"; Z'^i^b'^T^: ^'"- «• ""• '"-«»• •»»»• '£""11, J., Jour, at Geo., Vol. 14, p. 838, 1S08. Walther, J., Rioleitung in die Geologie, p. 818, 1897, 40591—7 Jfi !f U ; i 92 „.idst. of fine grained ^tr^tj^lfiX^^^^^ offiing fertonTS' rray\:^S^?t£t ?he climate of th. finer Vajned ^^t^ .ltXra?e «ub^^^^^ Morf bedded, it IS evident that these are suoaq ^ j^ ^^at the geneity of the conglomerate of the Cob^ser^s^ ^^gr^^^ variability in the matrix, m t^^n,^/: *7h^ coS t^e and in the rock types,. represented mt^cong^ ^^^^^^^^ varying degree of abrasion t" J^^^^^iectS the presence of of the conglomerates have )^f^?,^3Sics which commonly cross bedding n places are dUha^^^^^^^^ ^^^^ b^.„ belong to sediments ''}.'' ^^^^^^T°^'^ The conglomerates iThfSb:i'^Hrhr.s^^^ ''^^StSnt;, however. ^S^^^;:^^!^ 2^ conglomerates of the Cojalt series t^ Xh Se iAconsistent Bome features associated wij them wn ^^^ ^^^^^^^^ with a fluviatile origin. ^ J^^Xes ^re 2, 3, or even 8 feet contained in the co'^Kl^^^'f^f'X manv' Ses from the nearest in diameter^ and are commonly many m^^^^^ Moreover, occurrence of similar rocks in the oioer y deposited was the surface upon which tj^/^^^lrerate wa ^^^^^^ ^^ one of mature topographyj so that t^ ^^ i^^^ the large boulders ^^^^^ ,^^7^^%^^^^^^^ ^fficulty, it ha3 gentle gradients In o'der to exp Huronian period been pointed out^ that the ch^^a^^ j^^ J^^ds in regions where may have been semiarid and that a"r^| °° j ^ gj^g may be such climatic conditions prevai^bouldere ol larg ^^^ transported long ^fanc^ by rivers^ But « ^^^^^ 4 Z^^lf^^'^l''^?^ " everywhere characteristic of the «S*T ****-f """^ ^^1 •'5'°"'; ^^''^^^ "«"a"y distinguishes more recent auviatile gravels developed in arid or semiarid rerions n^vl^^^r'T ^^^ Pre-Cambrian atmosphere was deficfe^tTi^ FlSili ' ^^f*"""^ t''° ?*i\?*' *° ^"'"'d ^"'"atic conditions. Fluviatile conglomerates of the coarse unsorted tvoes which are characteristic of the Cobalt series are limited on thTearth's surface at present to regions of youthful topography or arid climates*. These factors, usually operating toeetherhavP resulted in the building up of immense accumulatfons of ri^Ir gravels on piedmont slopes and in interior basine. If it be assumed, therefore, that the conglomerates of the Cobalt series are of fluviatile origin this conclusion must be reached in the tace of the facts that these immense deposits covering a minimum area of 20,000 square miles, were built up in a region haviigTlow relief and a pluvial climate, conditions which in every particular are the reverse of those under which similar fluviatile deposits are accumulating on the earth to-day. ueposiis •^u-^^lv^!^'*i Deposition.— In a number of papers published within the last few years Dr. A. P. Coleman has advocated Ihe g acia^ ongmoi the conglomerates of the Cobalt scries, pointing out their striking similarity to the Pleistocene glacial de™)sits ^i«°K "°K^' '■°*^''? "* other parts of the world to which a g^c al ongin has been assigned. The principal features emphasized by Prlvi^i T™ m"^ *,''^ resemblance of the matrix of the conglom- erate to boulder clay, the enormous extent and great thickness of the conglomerate, the occurrence of immense bouLlel; at a distance of several miles from the source of supply, the great size, angularity, and variety of the pebbles and boulders of the congomerate and finally, the finding of scratched and "soled" pebbles and boulders m the conglomerate at Cobalt, Ont ' tainprf Zf" ^ -"^i?^ «I5"^' hypothesis, it has been main- teSh K J^^^}^^ ^"'^aces should somewhere be found beneath the basa conglomerate instead of the ancient regolith wh^ch 18 commonly present.' In reply to this objection, Dr Coleman has pointed out that "near the edge of a glLiated area '^^.1^* ^ BiMford, Geology of India, p. 397. Bi^n*V*"i*^"°^* ^'^- Exploration in Turkestan, p. 40 ^rrell. J., Jour, of Geo.. Vol. 14, p. 330, 1906 jrombndge, A. C, Jour, of Geo., Vol. 19 d 738 intl Wli IC" ril' S~- ^ ^'J- ^°L'2. PP- 271-300, 1907. Kussell, I. C.. Geo. Mag.. Vol. 6, pp. 289-295, 1886. Kioh, J. L., Jour, of 8oi., Vol. 18, pp. 601-632, 1910. 'Am. Jour. So., Vol. 23, nn 187-102 tarn BuU. Geo. Soc. Am., Vol. 19, pp. 347-466, 1908. •Ann. Rep. Bur. Mines, Ont.. Pt. 2, p. 58. Can. Min. Jour., Vol. 30, pp. 646-607. 40591—7} i\ 94 number of points at ^^^f **>f ^^^ "" ° ° ined is not great and Kekeko hills, in Boischatel townsh P, ^^^^^^ ^ breaking out who assisted t^e ^^J^Vo^^Satr^^^ were definitely some pebbles from the con8'°™|J^*^ xXIV A). The con- «cratched in several d^^^^^^^^^^^^ ,i,d has been glomerate »***>»!, P0»^\"^1 ^ "hat the scratches cannot be neither mashed nor faulted, so mat t exhibiting the typical rounded '<^ "t?l£te SideS bearing on the counted,* but smce ".^'~.""'' •"„,, .:j„ *!,« count was made Sl'?S^t?oiTSe"^af^i-^i - «i^-^ '*»• The results obtained were as follows:— Tlour. ol Geo.. Vol. U, p. 155. 19M. . pSrR^%tr«^a'b|««>.. ^»J Dept. o. Mine.. Can., p. 31. 1«». Ann. Rep. Bur. Mines. Ont., Pt. 2, p. 88. iw. • Plate XXIV B. 95 i ■V- I 1 Total number of pebbles and bottlden. Number ol ■cled pebbles and boulders. Percentage. IxxiBlity. 205 310 99 168 200 17 37 38 S4 60 38% 26% 30% Dester township, Pbntiac co.. Que. Kekeko hiUs, Boischatel township, Pontiac CO., Que. Labyrinth river, Dasserat town- ship, Pontiao co., Que. Labyrinth hills, Dasserat town- ship, Pontiac co., Que. N. shore Larder lake, Hearst town- ship, Nipissing district. Que. If it had been possible to break out the pebbles and boulders and observe them in three dimensions instead of one, the above percentages would certainly be greatly increased. In the preceding discussion of the glacial hypothesis, attention has been confined to the conglomerates of the series. One of the strongest arguments, however, in favour of Huronian continental glaciation is to be found in a comparison of the series as a whole, to the Pleistocene glacial, fluvioglacial, and post- glacial deposits of this same region— for each of these has its exact counterpart in the Cobalt series. At the base of the latter there is the conglomerate, which, like the Pleistocene glacial drift, is exceedmgly variable in thickness, and, like the drift, is unstrati- fied, in part, resembling till, is rudely sorted and crossbedded, in part, similar to the fluvioglacial deposits of kamcs, eskers, and outwash plains, and, in places, passes into unstratified grejrwacke containing scattered pebbles and boulders, thus duplicating boul- der clay.' Overlying the basal conglomerate, there is the stratified greywacke, argillite, arkose, and quartzite which have their parallel in the Pleistocene post-glacial stratified clay and and of lacustrine origin.'' In both of these deposits boulders have been found which have been attributed to floating ice.» The Cobalt series differs from Pleistocene deposits of northern Ontario and Quebec in the greater thickness of arkose and quart- zite which it contains and in the presence of an upper conglom- erate< overlying the finer grained member of the series. These conditions, however, would simply imply that the lake which covered the region subsequent to the deposition of the basal congl omerate was of longer duration tb'm that of Pleistocene JPrel. Rep. on Gowganda Dist., Geol. Surv., Dept. of Mines, p. 26, 1909. •Ann. ^p.. Bur. Mines. Ont., Vol. 14, Pt. 2, p. 33, 1905; Vol. 18, p. 282, 284, 1909. Sum. Rep., Geol. Surv., Dept. of Mines, Can., p. 278, 1911. •Jour, of Geol., Vol. 16, p. 153, 1908. . o A"»v ?*••• ^'"■- °' **"'™' Ont., Vol. 20, Pt. 1, p. 220, 1911. * See table, page 84. i\ I f I 96 time, and that following the lacustrine epoch a second conti- nental ice sheet advanced over the region irom which an upper conglomerate was laid down. If it be assumed, therefore, that the conglomerates of the Cobalt series are of glacial origin, then there are at least two till sheets present and the stratified grey- wacke, argillite, quartzite, and arkose constitute interglacial ^^The essential similarity of the greywacke and argillite of the Cobalt series to the post-glacial lacustrine c ays of the region is shown in the following table of chemical analyses Number 1 is an analysis of the argillite, and number 2 that of the stratified clay occurring at the north end of Lake Timiskaming. In order to make these more nearly comparable they have been recalcu- lated to a total of 100, omitting the water. 1° '^""'ber 5 a partial analysis of argillite from Lily lake, in the Gowganda district, is inserted. fr'iO..... AltO>.. FeiOr. FeO.... MgO... CaO... NaiO. . KtO... HO- HO+ . SO. ... 62-74 16-94 6-07\ 1-89/ 3-05 1-39 6-07 0-36 3-20 TI. 82-00 16-11 4-69 4-10 826 2-76\ 1-74/ 964 III. IV. 64-81 17-48 5-23\ 1-64/ 3- 14 1-43 627 P-09 87-94 17-92 6-83 4-86 0-20 3-00 1-98 010 61-84 0-84 4-73 2-84 Number I, ArgUUte. Ann. Rep- Bur. Mines. Ont.. Vol. 14. Pt. 2, p. «, im. Number II, Stratified clay, " . . .^ .^.- » P- "• '***• Number III, No. 1 recalculated to a total of 100, omitUng water. Number IV, No. 2 recalculated " Number V, Jour. Geo., Vol. 18, p. 660, 1910. It will be observed that in both the argillite and the clay there is an excess of soda over potash, a relationship which is usually reversed in normal sediments of the slate-shale senes. The large percentage of lime and magnesia in the post-glacial lacustrine deposits is undoubtedly due to the large wnounts of Palaozoic limestone which were denuded away by the Pleistocene continental ice sheets and were thus transformed mto glacial drift and later redeposited as clay. . • u • u* Concltmon.— Having assembled the evidence which might have a bearing on the oripn of the Cobalt senes, the following conclusions may be stated with regard to the climatic conditions and depositional processes in operation at the time these seai- 07 ments were laid down. (1) That the series is of terrestrial origin. (2) That the basal portion of the series is in places an ancient regolith. (3) That the stratified greywacke, argillite, quartzite. and arkose are lacustrine deposits. (4) That oeolian deposits are not represented in the series, (5) That the climate of this period was not arid or semi-arid and was probably cold and humid. (6) With regard to the mode of deposition of the major part of the conglomerate only two hypotheses need be considered. They are either of fluviatile origin or have been deposited from continentaJ ice sheets. From a consideration, however, of the difficulties of transportation involved in the fluviatile hypothesis and that the climate and topography of the region were wholly the reverse of those under which fluviatile deposits of this char- acter are accumulating on the earth to-day, and on the other hand, the fact that practically every feature of the Cobalt series has its duplicate in the Pleistocene glacial, interglacial, or post- glacial deposits of North America, that the pebbles and boulders of the conglomer.ites have a characteristicaJly soled appearance, and that striated pebbles and boulders have been found in two localities over 60 miles apart, it seems necessary to conclude that the evidence preponderates in favour of the hypothesis that the conglomerates of the Cobalt series were deposited from Pre- Cambrian continental ice sheets. In the above pages an attempt has been made to apply the criteria which distinguish the various types of continental clastic sediments, to the different rock types represented in the Cobalt series and thereby to reach a definite conclusion with regard to their origin. As a result it has been shown that not only has every variation in the series its duplicate in the glacial, inter- glacial, or post-glacial deposits lud down in association with Pleistocene continental ice sheets of this same region, but that no other known depositional process will so well account for all the many peculiarities and associations of sediments found in the series as the glacial hypothesis. Furthermore, the objection that striated surfaces have not been found beneath the basal conglomerate loses much of its force when it is recalled that only an exceedingly small part of the contact between the Cobalt series and the older complex has been observed, that the under- lying surface in some places has been smoothly eroded, and that the presence of the overlying conglomerate at these points gen- erally makes an examination for striae impracticable. With the progress of detailed geological investigation in regions where Pre-Cambrian rocks ocput, evidence is accumulat- ing which indicates that the processes at work on the earth's surface to-day were in operation in the very earliest T "lambri- an periods. The existence of Pre-Cambrian continer- j sheets would, therefore, be simply another link in the chain .vidence 1 -im pointing to the uniformity of natural processes from the very earliest time in the earth'a history of which we have any know- ledge. \GE AND CORRELATION. Since there are no fossils contained in the Cobalt series its age must be fixed solely from its stratigraphical rei.aionships and its lithological similarity to other series. It is known that these rocks are Pre-Cambrian in age, and that they he above a great structural and erosional break which occurred in the midst of Pre-Cambrian time, and that they, therefore, belong to the group of rocks which Logan classed as Huronian, but information is not yet available which will permit of their correlation definitely with the subdivisions of the Huronian as they occur on the •. )rth shore of Georgian bay or elsewhere in the Lake Superior-Lake Huron region. Post Cobalt Series Intmsives. NIPISSINO DIABASE. Distribution.— In a large number of localities throughout this region the rocks of the older complex are intruded by dykes and small masses of the Nipissing (Keweenawan?) diabase. There are two varieties of this diabase, one of which contains olivine, and the other is olivine-free, but the olivine-free variety is much the more common for it was observed in 17 different localities, whereas the olivine bearing type was seen at only 5 separate points. The largest dyke in the whole region, however, consists of olivine diabase. This crosses Lake Opasatika at the narrows which subdivides the northern and wider part of the lake into two expansions. It has a width of about 300 yards and outcrops as a continuous ridge extending for a distance of over 3 miles in a northeasterly direction from the lake. In addition to this occurrence, olivine diabase was observed at the east end of Kishkabeka lake, on lot 45, range II, Tr4cesson township, on lot 33, range X, Villemontel town- ship, and on the east shore of Bruere lake. LUholoffical Character.— The Nipissing diabase throughout this region is a rock of rem -kably uniform composition but of somewhat variable texture and colour according to the condit- ions under which the rock solidified. In the smaller dykee and along the margins of the larger masses, the rock is black and aphanitic, but elsewhere it generally possesses a greyish green or dark green colour and medium texture. The ophitic structure I 4 99 is always present and caa be readily i-ecognized even in a hand specimen. The porphyritic structure was observed in only one locality, along the National Transcontinental railway on lot 61, range II, LaReine township, where phenocrysts of plagioclase about three-fourths of an inch in length were present. The microscopic examination of the olivine free diabase shows It to consist of laths of labradorite, the interspaces between which are filled with augite, ilmenite, and, in some sections, micropegmatitic intergrowths of quartz and feldspar The presence of the micropegmatite like the texture of the rock, 18 related to the speed of solidification, for it is entirely absent in the fine grained aphanitic diabase which occurs in the smaUer dykes and on the border of the larger intrusions, and becomes more abundant as the size of the intrusive mass and the coarseness of grain increases. Apatite is also a usual original constituent of the rock and occurs as rod-like crystals dissemina- ted through the rock. As a rule, the diabase is more or less altered, the secondary minerals being caleite, epidote, zoisite, sericite, hornblende, and chlorite. The olivine diabase when examined under the microscope IS seen to consist of olivine and labradorite enclosed in augite The olivine generally has a rounded outline when in contact with the augite afld in some parts of the section has the same relationship to the plagioclase, but is more commonly cut off sharply by the feldspar laths. A dark brown mica is usually present in the olivine diabase and in some sections is associated with the ilmenite. The accessory constituents of the olivine dia- base are similar to those of the ordinary type, but the secondary minerals were entirely absent in all the sections examined, the rock ha^ong suffered practically no mineralogical alterations. Structural Relations— The internal structural relations of the IN ipissmg diabase of this region are very simple, the rock being remarkably uniform except for the difference in texture and the accompanying development of micropegmatite already described. X^o inclusions of country rock or evidence of modifications in the magma by the assimilation of country rock were observed. Ihe relationship of the olivine diabase to the ordinary variety was not ascertained in this region, but in other parts of the country where chese rocks occur, the olivine diabase intrudes the ?Swf *^u ^^ '^ evidently younger m age. The general similanty of the two rock types and the; geographical associa- tioii with one another, however, indicates . t they were intruded aunng the same period of vulcanism u d derived from th p. W.S''"'^ ^^°^' '^'~«'*«°' ^^^ S-dbury Mining District, Geol. Sun-.. Can., Sum. Hep., Geol. Sunr., Dept. Mines, Can., p. 199, 1910. *f 100 of basic magma which ""9"'*^^ '^'^^i. V ai„o believed that themargmsof themtrusions wnere vue , j t^e larger micropegmatite were developed. i\J ««/i rorrelotion.— The diabase dykes were not ob- SYENITE POBPHYBY. toSS» i W«Suy imique, lo, this rock .» not ob»md anywhere else in the region. TiihoUxrical Character.— The syenite porphyry is a massive length, embeddea in a pins ^" Kf J" . maintains the same char- of its contact. 101 It WM found on examining the syenite porphyry under the microscope that it consisted of phenocrysts of albite enclosed in a granular groundmass of feldspar and quarti, with sphenc, chlorite, carbonate, epidote, and chalcopyrite as accessory constituents. The plagioclases contain an abundance of inclusions of sericite and epidote which have resulted from their alteration. The outline of the chlorite is such as to suggest that this mineral has been derived from biotite, but no trace of the original mineral could be found. Structural Features. — The syenite porphyry forms a rock mass of oblong shape having somewhat irregular but vertical walls. As the Nipmsing diabase is the only other intrusive in the regiou known to cut the Cobalt series, and since the syenite is similar in composition to the aplitic diffcrentiat«8 which are associated with the Nipissing diabase in other parts of the Timiskaming region, it may be possible that this mass is also a differentiate from the diabase. The junction of the syenite porphyry and the basal conglomerate of the Cobalt series shows distinct evidences of the contact effects of the intrusive. On the north side of the syenite porphyry mass, the conglomerate is mashed in the vici- nity of the contact and on the south is traversed by innumerable joints, both of these effects being clearly due to the contact action of the porphyry. Pleirioeene and Recent. GLACIAL The Pre-Cambrian rocks of this region are nearly every- where overlain by boulders, gravel, s&nd, and boulder clay, materials laid down from a huge continental glacier which covered northwestern Canada and the adjacent portions of United States in the Pleistocene. In the southern part of the region covered by this Labradorian glacier there ore a number of till sheets separated by interglacial deposits, indicating that there were in reality several of the- j ice sheets, in the district here described, however, there is no evidence, as far as was ob- served, of the presence of the earlier glaciers, all of the till which now covers the surface of the region having been deposited pre- sumably from the last ice sheet. The movement of the contin- ental glacier in this district as shown by striae was from a direc- tion slightly west of north. That the contmental ice sheets were capable of considerable erosive action is evident from the general mammallatory contours of the surface of the region, from the gently sloping curve of the loa .^^ 0. rock «p«- 2 ss sss rs^?KI?1cS^)'S y observed wherever %!°^-^ ^^KJ^Tand grooved Burfaces can feathering "(Senciei.. The f^^^^^J^ oflake. in the summer generally be seen along ^'^t.'^oy^rvation in this pl«M5e being Xn the water « low. th«rpre.«v^ atmosphere afforded apparently due t« *^« P^^TKe wat«r of the lake, during a large part of the V^f "^ J^J denudation accomplwhed It is probable, however that the aenu ^ ^^^J ^^ar- by the continental i^^^^^^VthepScambrian rocks under- aLr ard that the "'^^i"': °\tf ^^eatures with the pregla- lying the drift correspond* '>» 'Th° principal evidence in favour ck topography of *be W°V JJX^esWtion. i« to be found of this conclusion, m the districiun continuous for many in the presence of n««°^'0'«' ™t^^heir °"B^ ^ *'*" * •°" Siles. which certainly do not owe *h«r °ng^ ^^ ^^^ ^. ,»^„ 8inte their trend «, m .«o™fJ_^Xof the Laurentian plateau of ice movement. B^'J'i^Sflce S preglacial topography ha« evidence pointing to the existence oi P » , ^ ^ q. Wilson Sn citerby A. C-L^^^'^^^^jlenW indicating that glacia and others,* «^1 .°Utut ^W S*? ?nSrely destroy the preglacial ?X'a7y StSar^aA^^^^ ,orms only a thin ^he glacial drift in this f.f »^J^ffing Vocks. the thicker mantle over th-. surface of the un^J^y'Jf ^he prUence of the accumulations being very local- ws^j^^ ^ j^g^ p^n postislacial clays which l^^^}^^^X«co^^ which occurs every- S^the region and to the thick tores. B information with where, it is K««"*"y ^'K dac^^^^^^^ regard to the character of the fjawa ^ ^^^^.^ted by a stream happen to occur on a Y^LTAoI^ Transcontinental railway, or a cut on the ^ne of the Na^iona v^^ ^^ ^^^^ frequently Boulders ar«««'»*^'*^,„!!^llm which the more easily trans- observed in the Vi^AmSveTeJ swept away.^ Boulder clay ported portions of the till have D^ h ^j land portage was observed at t^e north end oiia » . ^^ ^^^ shore TrSi Ogima to Summit lakej^^^jf^SlEiis iJce. This materia^ of Duparquet lake ^nd °"*J^ '**foV not a ingle occurrentvB was Tnt^^rS inKit'sXg 'the line oi the National Tran. •'•■'U'^-*"'""" . Bull. Geo. 8oc. Am. VoJ^- ^'^^o.';: i^r^^ ■ 103 intinental railway throughout its whole extent through the district. Home of the glsrial depoHitH of the region consist of till that itt partially nortctl and roughlv ntratified and in rvidently of fluvioglarial origin. This iluvioglacial material may take the form of elliptical shaped hills (kamcs), the longer axis of the ellipse havmg a north-south trend, or may b« spread out over a wide stretch of country (outwash plains). A good example of the former having a tail-like prolongation to the south, occurs on the National Transcontinental railwav west of thetcroBsing of the La Sarre river, and of the latter in the central tf Tr^cosson township. A seotion through the end of the itme near the La Sarre rivor is sho\ i in Fig. 6. kan Strafifia^ clay Svrtd cros-'ibeJdid BouUvs anii Sand Fit. 6. DiagTainmatir w-nion tlirougli kamp on the National Traoicontinoiital railway in ranice VII, L« Sarre townuhip. POST-OLACIAL. Throughout a large part of the district the glacial drift is overlain by imiformly stratified clay and sand which has filled in the minor inequalities of the underlying surface, thereby forming local plains. The contacts of the stratified material and the drift as exposed in the cuts along the National Trans- continental railway are usually gradational, the stratified clay giving place to stratified sand which in turn passes downward into the typical glacial or fluvioglacial material. The bedding of the stratified clay where it lies upon the drift or a Pre-Cam- brian rock siu^ace, is characterized by remarkably steep deposit- ional dips (Plate XXV). These irregularities disappear within a few feet, however, in tlie overlying beds. The greater part of these stratified deposits consist of uniform beds of clay from one-half inch to three-fourths of an inch in thickness, which are interlaminated with layers of calcium carbonate about one- eighth of an inch thick. In places, the c!..y contains consider- able sand and a bed may contain two or three subsidiary layers 104 a due to variation, in the «md contejt^ e?ay''aSd'iS.'Sicfly nof nearly - exten«ve ^ ^^^^-'^S depciU In whic?. 3 ta abundant. uniformly utratified poBt-ria«ial It i« believed that these «n"°J^'V hich occupied tbw depolits were laid do^. I™"* » {T he lant UbradJ.rian ice re£on Bub^quent to ^^e retreat oi^ proponed for thin body SSrt. The name Lake Oj^jay »»j'^ ^J P,„^ ,ay for the mon of water by Dr. A. P. C^olemwi. 1 P divide and the part between the Jt. V*^^^^" „,!„« part of its hwtory at retreating continmtal Rlaoer »ijJ^.f^"^„J ba«in. for stratified ^Mt was connected with the \'™'",''';^ ^^nd Trdce«son town- 'ry JSr. on the height oflandml^^^^^^^ ^^^j^^„d , Hhips and.extendH <="^^''"J^"teight of land the clay occurs at Lake Timwkaming. On the ""Rnj " ■ „herea« in the vicinity aJeLation of 1074 fee '!^^;^'^^'Sl:,lS oi only 800 feet, of Lake TimiBkammg '*,.'^'''J/!h*^^L in these two localities The difference in elevation of Uitciay ^^^ ^^^j may be due either to th^/'JS ^r"o SSg since the depos t- n^n which the clay r^^^TSc^u^s In%outhern O^^^^ ion of the clay, or to both of JJ®f ^J'^aches of Lake Algonkian Goldthwaite' hasestimatedthat tne dc«^ ^ ^^^ je Si Lake Iroquob have^n tihed ^^^^^.^^^ ^.^,^ similar towards the «outhwf^t M^d '^^jy i^^egiou. iiut in order tiltmghastakenplacemthc liroiBKawuB * ^^„^ ^. cd to ascertam whether «"«=J,S°Se treleVation of the beaches it would be necessary J? J**™'°^oJ yet been observed and may of Lake Ojibway, jnd t^^^* J^^^t „( ^ng duration. not be present *«' **^^/,7vf J:'^tho8« localities where the stratified It is most probable that nt^se^ ^^^^ ^^ together clay is mterbedded with calcium caroon j^.^ ^ represent seasonal deposits, J^^^^^J^ the winter. If it dilring tbe summer and thc^«^»^| .|^ ,i y represents be assumed, therefore, that ewn D«a counting the number of the deposition of » «^K^« ^f^he Wh of time the lake occupj^ rdirtfft^-^4 r £ ^^^' comparatively short lived. throughout the repon The application °V„T,«dMableinf ormation as to the history would no «ioubt afford conaderab^e^iuo ^^ ^^ existence In l^W^r^ *^« NTt?om.l transcontinental railway i 105 went of Cochrane, Ontario, arcording to Mr. M. B. Baker, thrw potti-glaciftl locufithnu dcponitit conRWt of altornatinK layerH of clay and find usually half an inch, hut In places reaching 3 inches in thicknejs, the total thickness in the deepest cut observed being 2& feet.' Awuming that a layer of sund and clay to- gethei represents an annual deposit and has an average thick- ness of 1 } inches, the maximum number of beds in that locality would be 245, which is approximately equivalent to the number observed by the writer. Mr. Baker's measurements, as far as known to the writer, arc the only data as yet available from which the numlier of beds laid down from the lake in other districts roifiht Im^ determined.* In th'>Me portions of the region which arc underlain by sand, notably in Tr^cesson township, typical sand dunes are exten- sively developed. The larger part of these are now preserved from the action of the wind by their forest covering and were evidently formed long ago, but some are of very recent origin, for in one locality where the vegetation had been n'moved by a recent forest fire, several birch and banksian pine were partly buried in sand. The Quaternary clays <»f this region very commonly contain concretions of carbonate of lime which are fantastic in form and, in some cases, possess a striking bilat«'ral symmetry. Photo- graphs of a numwr of these are shown on Plate XXVII. Thexe peculiar segregations of material arc most probably related to the solution and redeposition which accompanies the shifting of the grouno water level. As the clay in which the concretions oc-ur contains a large amount of calcium carbonate, this material if taken into solution wherever water percolates through the soil, an action that would be especially active in the spring of the year when the clays are saturated with water from the melting snows. )t is improbable that there is much free cir- culation of water in these impermeable clays, so that when the soil becomes dry during 8eu.«ons of drought and the ground water •eve', passes downward, the arbonate of lime is redeposited. This oeposition having once -mmenced at a given point tends to continue at that po'nt and in this way a concretion is built up. The peculiar symmetry of the resulting forms can scarcely be accidental and may L^ related as suggested by Todd' to the process by which additions of material take place in crystal growth. :Ajui. Bcp., Bur. Mines, Oat., p. 230, 1911. Coleman, A. P., Ann. Rep., Bur. Mines, Ont., Vol. 18, Pt. 1, pp. 284-283, 1909. •Bull. Geo. 6oc. Amer., Vol. 14, p. 3M, 1903. 106 5rl i ■■ ! •I i ;i i STRUCTURAL GEOLOGY. OEOWejCAh HISTORY. 1 i,«T« nf the Abitibi district The description of the fJ^.T^bfl^sfor^^^^^ outline of ^he mav be appropriately concluded OY «■ ^^ { t^e region. The fucLiion of events ^rSrict i^ common with the whole of s ' ^.; 5 107 the centre of one of the greatest outbursts of volcanism which has ever occurred in the known history of the earth, for immense extravasations of lava, thousands of feet in thickness, were piled up over hundreds of thousands of square miles, far exceed- ing m extent and thickness the lava fields of the Columbian plateau or the Deccan basalts of India. The character of these volcanic rocks is such as to indicate that they were largely extruded beneath the sea, although it is probable that owing to orogenic disturbances or the accumulations of the lavas, land was formed at times, which underwent denudation and thus furnished the material for sediments associated with the volcanics. Along with these surficial evidences of vulcanism, successive bathtn lithic invasions of acidic rocks occurred, accompanied by orogenic movements which folded the volcanic rocks into a synclinonum Une or more intervals of denudation also occurred during this early period, for the batholithic masses were exposed at the surface and underwent erosion from which great thicknesses Of arkose and conglomerate containmg granite pebbles were built up along with the regional extrusions of lava. This early era of vulcanism during which the Abitibi group, and granite and gneiss of the older complex originated, was followed by a second era of denudation which was just as remarkable for the absence of igneous activity and orogemc movements as the era of vulcanism had bera renaarkable for their frequency. The cumulative work of ages of denudation eventually resulted in the destruction of the larger part of the volcanic and sedimentary rocks of the older com- plex, so that they now remam only as truncated remnants folded into the batholithic masses of granite and gneiss. The era of denudation was finally terminated by the accu- mulation of a widespread series of coarsely clastic sediments of such a character as to indicate that they are all due to glacial conditions, there being evidence of the existence of two till sheets, which are separated by widespread interglacial lacustrine u6pOSltS. The next event following this Pre-Cambrian glacial epoch as far as can be learned from the geology of the region, was a period of ipeous activity in late Pre-Cambrian (Keweenawan) times. Whether any volcanic rocks were extruded in the region at this time is not known, but, if they were ever present they have been long since eroded away, for they now occur only as dykes and intrusive masses of diabase and syenite porphyry. Slight orogenic movements also occurred about this time which folded the Pre-Cambrian glacial series into gently dipping anticlines and synclines. Following the Kewee- nawan, a second era of denudation began iu the region which except for a short interruption during the Palseozoic when a 40591—8 M.' 1^-' 108 down, continued w yb\90Z0\c sediroents so has largely removea^ lecture. . . , q! this region extent « a "?»*^' ^JJ^ in the 8eolo»c^>„ 0,7 ^^ ^„^ered the The closing evenw ^j^ental R^i^l^^X America in the are closely relat^ to Jhj^^^^^ern part o^ ^orth Junej^d till was greater part <>« t*^? "^^r mantle o! gravel, sanw, ^^^^^ ^ Pleistocene. ^J^t^'Jegion by the last of tj«jf ij^^ial depo- jS. o!l»oV£ ^i'.^S'oX'^-^^ o. the Kified clay and sand wer outstanding glacial drift. ^y^e it is seen .t°f„"tbe stupendous * From the a^^^°Sory of the region are tnesw^ features in ^^^XSKSy h-^*^^^ vulr uism ^^'^^Sd an almost undistiKtja^^^^^ j ^ 1 til ! I Lik. 109 CHAPTER V. ECONOMIC GEOLOGY. GENERAL STATEMENT. Within the region described in this report there are no producing mines and only one property in which a mining plant has been mstaUed. The district, however, has not been prospected except m a very superficial way, so that the fact that no important discovenes have as yet been made has little bearing on its future possibilities. The deposits which have up to the present attracted attention are the molybdenite bearing, pegmatite dykes and quartz veins, and the auriferous quartz vevaa or veinlets in ferruginous dolomite, aplite, and quartz porphyry. ^ ' GOLD. GENERAL FEATURES AND SUBDIVISIONS. Practically all the rocks of the region are traversed by veins or veinlets of quartz which are more or less auriferous, but the most important by fa,r are those occurrmg in the rocks of the Abitibi volcanic complex, and more especially in the ferruginous dolomite, aplite, Mid quartz porphyry. These are believed to be genetically related to one another and wiU, therefore, be des- cribed in a group by themselves. Quartz Veins and Veinlets in the Rocks of the AbUibi Volcanic Complex. Veins or veinlets of quartz containing gold are now known to occur m the region described in this report, in the Larder l^ake district, at Porcupme, and in numerou° other localities throughout the nort;hem part of the Timiskaming region As will be shown later, there are certain features associated with these occurrences which point to a similar origin for all. In the following pages, aa attempt will, therefore, be made to correlate the observations of the writer and others m these various localities. 40591— 8J 110 'M riBSTJBE BT8TBMB. Sh ride of the C'S't .ZflTOyil S i uVtS °' ' U SCsien from Om 6.^m that the vemlets md veto eiiclosiug rock. 1 f^«. «*"fY ""j^^ j-te (Kerr-Addison, Reddick, uSe inSing the strike of the dolomite as m Figure 7. Tnthe Porcupine district, according to Mr. A. G. Burrows, a°Ld ^WT'siSTei" ^essrd'sssx.^-, iLm. Rep. Bur. Jmes. Ont.. Vol. 20 Pt. 2, P- 21. 1911. «mS* oI Porcupine Gold Area, Bur. Mines, Ont., 19U. Ill N Fig. 7. Stnke and dipa ol fimires io ferruginous dolomite, occurring on the north ride of the Cascade rapids on the Kinojevis river, Manneviile township. Pontiac county. Que. The ■tmctural trend of the dolomite is indicated by the heavy line fm 11 4 -it 112 ■ U 11 »!.., i m ! ' -'SrSS-a^3^Sa^*"^ 4 118 Fig. B. Strike of finurea occurring on lots 10 and 11, concession II, Tisdale town- ship, Sudbury district, as shown on map ot Porcupine Gold Area. The structural trend o( the enclosing rock is shown by the heavy line. 114 having a northwest-southeast trenu. These are, therefore, fi^sSonl which the gold bearing solutions percolated were rnnroximately 45 degrees or less to the structural trend of the which folded the rocks of the region. That such stresses were prSi Tthe time the fissures were f°™«di8 probable from thP evidence presented elsewhere m this report that the vein miing material is derived in part at least from ^cidic rocta and that the intrusion of these acfdic rocks accompanied the foldmg °'^Vt°hfrol?rn'ffii the gold bearing veins of. the Timis- kaminVrerion occur were fractured by compresave stresses SS in the same direction as the stresses by which they were Sat^d then, in the case of an irrotational strain, if th« rel « KsiuiS w^re greatest in a horizontal ^^'^^Z^^^Mhl to the reirional stresses two systems of fissures woum uc developed wUch, on a flat erosion surface, would cut across the tre^d Jf the enclosing rock at an angle of approximately 45 de«ees but, on a vertical surface, would.appear Parrf el, that is Se discordant relationship would be '^ strike. •"' ^""tie^l ITthpr hand the relief of pressure were greatest in a yerucai Erection at right ^lles to the regional stresses, two systems o fractures may indicate their mode of onpp (1) ''y *^®"1'"^, ♦v^ffi^nrps alone which the quartz veins occurrmg in the Pre- CaSn vlK complex'of the Timiskaming region were developed. a 4 116 CHARACTER OF DEPOSITS. Form.— Those deposits which occur in association with the ferruginous dolomite consist for the most part of innumerable small anastamosing veinleta of quartz from 1 inch to 6 inches in width. In some places these are bordered by a zone of dolomite which when dissolved away leaves the quartz with a denticul- ated surface (See Plate XXVIII). In other plants the vcinlets have no definite walls, the junction of the quart:; and the wall rock being gradational. In such localities the country rock may be almost entirely replaced by quartz. The larger veins occurring in these rocks of the Abitibi group are very similar in character and in form regardless of whether they occur in the ferruginous dolomite or any other member of the volcanic complex. They vary greatly in width from less than a foot to several feet in short distances, and may expand abruptly to a large mass of quartz 30 feet or more in width such as the mass oc -rring in the ferruginous dolomite north of the Cascade rapids on the Kinojevis river. The essontial simil- anty of the form of these deposits to those of the Porcupine district IS shown by the following quotation from Mr. Burrows' report on that area. "The irregular Assuring has produced a great vanety of quartz structures, varying from the tabular though often irregular or lenticular, vein which may be traced several hundred feet, to mere veinlets, often only a fraction of an inch m width and a few feet in length, which ramify through a rock which hac been subjected to small irregular fissuring This latter variety is well illustrated in the fissuring of ankerite bands, so characteristic of many of the gold deposits of Porcu- pine. Irregular and lenticular bodies of quartz often occur which may have a width of 10 or 20 feet, but which die away in a distance of 50 feet. Again there are dome-like masses of quartz which are elliptical or oval in surface outline, but whose underground extension has not been examined closely The most conspicuous dome masses are those of the Dome property, where the two largest are about 125 feet by 100 feet." Composition of the Deposits.— The mineralogy of these deposits IS comparatively simple for they consist almost entirely of milk-white quartz. Ferruginous dolomite is usually present in some abundance, but all the other mineral constituents occur in exceedingly small quantities. The most abundant of these are pynte, chalcopynte, galena, and gold. Mr. Burrows also notes the occurrence of zinc blende, pyrrhotite, argentite, feldspar and tourmaline in the quartz veins at Porcupine, and since the publication of his report, the silver telluride, hessite, and the calcium tungstate, scheelite, have also been reported. In the region described in this report, tourmaline was observed in quartz "hi I H^ 116 mica in veinleto in P«J[Pi>3y'^iJ'TCd Fortune Uke. The Mining Company, tf*r^,ide S<^^^'''' ^"'^''^ ^ *-* Kir. R. Harvey.' COMPOSITION or THE DEPOBITINO BOLUTIONB. of aplite, quartz iwrphyiy.wd related ro^ s occurrence of thermal ^^^\'°''^-, ,t ^^^SSor^^ra^^iiB sb np\^d inthequart«ve.Mofth-«amemm^^^^^^ ^^^^^^^^ ^j^.,b the aphte and quart* porpnyry.wia ^ effected the rep\^'^^^2imra^S^^d^^i^' ^^^^ that ition to those from which *•»«<»""" 7„tu_ "country rock will a Btudy of the changes brought about in the count^^^ afford some infomationMte the composmo^^ wj^^ ^^ solutions. In the "el^^^'O" °J JJ^Ss specimens of the most partial analyses given on pages 64 and ^^^^ ^^^ .^ striking^ types of ^^e ^o^i^i^oSrcomSte-were generally which the replacement had bwntMsicomp transfor- aplite are as follows:— iMin. Oper. Prov. Que., p. 83, WW. \ . 117 Number 1 ia a sli^htiy altered aplite from the Gold King claim, Hearst township, Nipiming district, Ontario, analysed by Mr. M. F. Connor.' Number 2 is a chrome mioa bearing ferruginous dolomite from the Harris Maxwell— a claim adjacent to the Gold King — Heantt townuhip, NipisHing diotriot, analysed by Mr. M. F. Connor. This rock under the microscope nan be seen to consist chiefly of dbito traversed by fracture lones filled with ferruginous dolomite and chrome mica. From a comparison of the chemical composition of these two rocks, it is evident that in the transformation of the aplite there has been a^ .ibstraction of silica, alumina, and soda, and an addition of carbonate of lime, magnesia, and potash. The solutions which effected the metasomatic alteration of the aplite, therefore, originally, contained an abundance of carbon dioxide, lime, magnesia, and potash, and later, as a result of their metaso- matic action, would also contain alumina, .silica, on soda.' The chemical compoHJtion of the depositing solutions can also be inferred from tlie minerals contained in the quartz veins. Among other constituents there were present, as shown by the composition of the deposits, silica, carbon dioxide, iron, calcium, magnesium, chromium, gold, tellurium, copper, silver, lead, boron, potassium, and soidium, although the proportion of many of these elements was no doubt very small. BOCRCE OF THE DEPOSITED MATERIAL. In the report on the Porcupine Gold Area, Mr. A. G, Burrows concluded that the quartz veins of that district were related to granitic intrusions, the principal evidence on which he based his conclusions being (1) the presence of tourmaline and feldspar in the quaitz of several deposits, and (2) the occur- rence of gold in quartz ^ einlets in aplite. In the Larder Lake district and in the region described in this report, the association of the auriferous quartz with aplite, quartz porphyry, and the ferruginous dolomite which has result^ from the alteration of these rocks, is still more striking than in the Porcupine district, but this association may be due to the presence of the fractures in the aplite rather than to any necessary genetic connexion between the aplite and the auriferous quartz. The presence of boron and lithium* in the dolomitic rock and the minerals tourmaline and scheelite in the quartz veins, however, suggests a derivation from granitic rocks since boron, lithium, and tungsten are ainnng the common elements contained in minerals of pegmatites. It seems improbable, on the other hand, that ■Chemiit, Mines Branch, Department of Mioea, Canada. 'Compare alteration in noda feldspar dyliee described by H. W. Turner, Jour. Geo., Vol. 7. p. 37», 189B. *QBart. Bui. Caa. Min. Inst., No. 14, p. 187, 1911. I i ' h I 118 present when the ores were deposited. AQB or DCPOSITH. With regard to the age of these deposjtH. it is "jno^ »*»»{ ihAv were^rmed long before the deposition of the CobjUt they ''«'«-;°™!^.'"ff the ferruginous dobmite occur in the ^i 'tte to£g h«i been „compli.hedM,d hence ijter the Lt bitholllhio inlrinions ot granite Mid gnem. CONCLU8I0K. % 119 maMcs of countrv rock by corboiutes and other mincralR, and later deposited the quarti in fianun* and perhaps also in part by replacement of the wall rock. There doen not appear to be any definite evidence on to the original source of the cir- culating waters, hut the presence of certain constituents sug- gi!- is that the deposited material was derived in part from the granite batholiths or their apophyiM-s, and in part from the yitibi volcanics. It should l)c noted, also, that, from the evidence cited as to the age of these deposits, it is probable that they were formed almost imnieiliately following the last intrusion of granite in the regioii, and that at such times any waters circulating in the vicinity of the intrusive would certainly be thermal and contain clement:4 common in pegmatite minerals, and it is possible that the gold may have been obtained from the same source. Veina of Quartz, or of Quartt and CaleiU in Granite, and in the Rockt of the Pontiae and Cobalt Serieg. The veins of this class have not been classed together l)ecause of ony assumed genetic relationship between them, but because of their general similarity in mincralogical compo- sition and because they so far have not proven to be of much economic importance. They arc commonly well defined veins of quartz or of quartz and calcite from a few inches to several feet in width and contain small quantities of sulphides such as pyrite, chalcopyritc, galena, and zinc blende. Assays from many of these occurrences have been procured by prospectors, but none of those reported to the writer exceeded $2 or S3 per ton. The veins occurring in the granite are generally large but very irregular ; those in the Pontioc series are generally small and occur irregularly strung out parallel to the foliation ; those in the Cobalt series are more uniform and continuous. COPPER. Although the copper bearing mineral chalcopyrite was observed in numerous localities throughout this region, in no place was a deposit seen which was of sufficient extent to be of commercial value. Wherever the chalcopyrite was observed, it occurred in quartz either as small aggregates or minutely disseminated. COBALT AND NICKEL. A number of deposits of pyrrhotite were observed in the Pontiae schist, two of the largest of which are exposed on the ' ti 120 shore of Lake Opasatika, one on the south shore of Klock Oil -and the other on the east shore of the lake, about one-fourth in., north of the entrance to Moose bay. A sample from the ^8t mentioned occurrence collected by Mr. McOuat in 1872 submitted to Dr. Harrington of the Geological Survey, and found to contain traces of cobalt and copper.' MOLYBDENITE. Molybdenite was observed in the district described in this report, in a pegmatite dyke in the granite which forms the island at the north end of Evain lake, and is also reported to occur in pegmatite in the vicinity of Caron lake, but in both of these localities the quantity of the mineral is small. Molyb- denite also occurs in the region included in the accompanying map, on the Kewagama river and on the peninsula in Kcwega- ma lake, but this district has been examined by Dr. J. A. Ban- croft for the Quebec Department of Mines and will not be des- cribed in this report.* PROSPECTS. UNION ABITIBI. The claims of the Union Abitibi Mining Company are located about 2 miles northeast of Lake Opasatika on the north shore of Renauld lake. There is a small remnant of the basal conglomerate of the Cobalt series exposed on the road which borders the northeast shore of Renauld lake, but else- where on the property all the rocks exposed belong to the Abitibi group and consist largely of ellipsoidal basalt intruded in places by dykes and irregular masses of quartz porphyry. Two of the porphyry dykes occurring on the south shore of Fortune lake have been largely replaced by ferruginous dolomite, and are intersected by veinlets of quartz and ferruginous dolo- mite carrying coarse gold and gold toUuride.' An east-west belt of dolomitic sericite schist in which some veinlets of quartz were observed also occurs on the property. 'Rep. of Prog., Geo. Surv., Can., p. 122, 1872. 'Johnston, J. F. E., Sum. Rep. Geo. Surv. Can., p. 138, 1901. WUaoD. W. J., Sum. Rep. Geo. Surv. Can., p. 123, 1906. ,...-.. Walker, T. L., Molybdenum Ores of Can., Mines Branch, Dcpt. of Hincs, Can., Witaoii, M. E.. Sum. Rep , Geo. Surv., Dcpt. of Mine Can., p. aor, 1911. •Min. Oper. Prov. Quebec, p. 83, 1910. 121 The discovery of gold in this locality was made by Messrs. Oilier and Renauld in the summer of 1006, and during the following winter the Pontiac and Abitibi Mining Company was formed to take over the property. During 1907 a few test pits were sunk on some small calcite and quartz veins but no further development work was done until 1910, when a saw-mill, engine, boiler, and compressor were installed. At the time the '•roperty was visited by the writer, in October 1911, an inclined ••hait (55 degrees) had been sunk to a depth of 155 feet and drifts wen? Loi,4 driven towards the northeast and southwest, at a deptl; of IJO feet on the shaft. The total amount of drifting accomp'i ihed was about 300 feet. With the exception of part of Me northeast drift which was being extended into the aujteoe^t basalt, all of this work had been done in the band of dolomitic sericite schist at a point about 150 yards east of the occurrence of gold in the quartz veinlets on the shore of Fortune lake. The buildings on the property consisted of an engine house, camp building, office, shaft bouse, and a building to cover the saw-mill. A mill was being constructed. QUINN CLAIM. The Quinn claim has been located on a brecciated zone in the greywacke of the Cobalt series, on the north shore of Dushwah (Turtle) lake. This zone is about 6 feet wide and consists of fragments of greywacke cemented by quartz con- taining considerable pyrite and chalcopyrite. The work ac- complished consists merely of a small opening on the surface. GOLD BELT CLAIM. During the years 1907 and 1908 some development work was done by the Gold Belt Mining Company on some occurrences of quartz in the vicinity of the north end of Lake Opasatika. The principal part of this work consists of a shaft about 25 feet deep on a vein of quartz which cuts the Pontiac schist at a point on the west shore of Lake Opasatika a short distance north of the entrance to Klock bay. This vein has a width of 2i feet and outcrops for a distance of about 150 feet. It consists almost entirely of quartz, but some feldspar and scapolite occur along the margin. RENAULD CLAIM. The Renauld claim is situated directly north of Nabugusk lake. The rock of that vicinity consists of granite and is cut 122 by numerous veins of quartz and of quartz and calcite. In one of these veins the quartz contains considerable chalcopynte and a few flakes of dendrictic native copper; and m another, calcite containing small quantities of pyrite, galena, chalco- pyrite, and zinc blende has been deposited m the centre of the vein as a filling between the crystals of quartz which have grown outward from the wall rock. BEATTIE CLAIM. A brecciated zone extends across a smi.ii island occurring at the north end of Lake Duparquet, in which considerable quartz and some carbonate have been developed. It was reported that assays of $20 per ton had been obtained from the quartz of this deposit, but an average sample taken by the writer contained no gold when assayed by Mr. L. Leverin of the Mines Branch, Department of Mines. 123 INDEX. Abijevis billg, elevation of ,, ,, " lake, valley of "• j* Abitibigroup, characters of ,. 'j " reasons for adoption of term . '.'. t\ ^^ regional distribution of ',.'.'. J, ^^ Bee Abitibi volcanic complex. " Pontiac series, " " schists and amphibolites. slate and phyllite of ., . , subdivisions of „ Jf Abitibi lake, area of .i4, 45 bathoUth ^ II canoe route to ^ ." « ~% relation with slate and phyllite.... «? structural features of ?J structural relations. ... 5? subdivisions of J? Acknowledgments ~ Actinolite, rock constituent '.'.'.'.'.'.'. 17 kn ki a\~i Age, see correlation. 47, 4U, 54, eo.iJ Agriculture, notes on Albee lake, canoe route through L " elevation of f Albite, rock constituent «« ti ' ~o ,\, Allanite, lock constituent ' ' '*• '"' Amphibole, rock constituent J? Amphibolite, Abitibi volcanics, origin of'.'..'. «, iS << " " petrography of. ...[['.['.'. .'.'.'.',',,[',[[[ L ., ri x- .. , see schists and amphibolites. •> rontiac schist, description of 79 , .,.,, " " origin of ,, AmygdalrMal structure, as developed in Abitibi volcanics. ..'. S Analysis, see chemical analysis. >-"i"i.o au Andesite, of Abitibi volcanics, petrography of . .-, Animals of district =- i- j 47 Apatite, rock constituent... '.■.;■.■.■.■.. ■.■.'.■.■.;■. 4B (iri 87 71 7« « Aplite, chemical analyses of 40, 00, 67, 71, 78, 99 " dykee 1>6 II from Kiaojevia river, petrogriiphy of..... ■.;..■..'.■. .' II from Larder lake, petrography of 5? original form of ferruginous dolomite m 22 40501-9 • 124 ii tAOM. US Aroentite in aurUerou* qusrti yeiM. ■■■••■. : • • AiSilllte and greywacke of AbiUbi volcanica, lee greywacke. AigilUte of Cobnilt terieB, «ee greywacke. •» ba Arkose and quartiite oT Cobalt ienei. character '• • ■ • '.i; ' i' W-i l^^Sts"ivT<5'p^^^^^ Dufresnoy lakes! and BioiI^S^S;S&::::.:;:::,:::::::::::::::;---:--«>'^ Biotite lamprophyre, see lamprophyre. Biotite schist, Pontiac series, description of *« " origin of Birch, canoe, occurrence of Birds of district ■ Black spruce, occurrence of. Boulder clay, distribution of Bowman, Isaiah, acknowledgments to Bun structure, see ellipsoidal structure. Burwaah, E. M., services as field assistant 20 38 37 38 82 122 15 29 2 2 99 71 73 28 30 28 102 3 KnS-c^co^tHl^ntie;*^ Carbonation of Abitibi volcanics g Caron lake, canoe route through jg " elevation of j2o " molybdenite on ; j j j Chalcopyrite in auriferous quarts veins j^j " rock constituent ^ Chauvigny lake, ferruginous dolomite on j jj Chemical analysis of aplite ^^| " " dacite fg - " diorite •. ai 05 M " ferruginous dolomite "• ^ " tilrnr'''!^;.::::::^; 47.i9;-8o,-54; 61, 62; 67;7i; re^^ m '..v.'.'..'.'.'.'.'.'.'.'.'. 81 Chlorite, rock constituent. Chloritic locks distribution of. " " petrography of. Jut 125 ■a 4 Chrome mica, in aurifeious qiwrU vein*. . . , ,« ^ lock comtituent 04 iS Cl.y «.d «»d?c"h:,SiSrT"^ .". '""'^'^ '*°'°"''"' '■'■'■■'■■■■■■■ ' S " " concretiom in IS " distribution of JS " origin of J* Climate of district "'* Clinton strata, presence 'ktandatgiiiite. :::::::::::: «, s litholo»cal a>>scription of S' gj :: :: orJIlSrftem,:::::::::::::::::::: >'•*?. g .. ., regional distribution of i\' ** .. „ relations to underiying rocks ' m sections of »5 _ structure of 25 oi :; r JSl^^'"::;::::--'--'- •■■•■■■■- n'\" • "pper conglomerate So' « l-oncretion? "n cla<' ow, so Conidomerate of Cobalt ■series, see basal conglomerate: '*" r'r>n.i„.«>»<..f D ..• " . ■«« "PI*'' eongloraerate. Conglomerate of Pontiac series, description of ,, „ I) distribution of j2 cZ^' p'^l^n™ o?.""". **•■"" "^"^-'hiiithic rocks: : : :::::::::::::::::::: 37, ^ Correlation of Cobalt series *" [] Nipissing diabase. ::::::::: ,K Pontiac series '™ Coutchiching series, possibly repie ented by Pontiac scries 7" Cretaceous peneplain, possible presence of *■««"«» 78 Crooked lake, see Caron lake. " Crown Lands Depaitment of Quebec, 8urvc> j by Dacite of Abitibi volcanics, chemical analysis of . . ., Dagenais, L. E., services as field assis-tant ,*?. Dassert lake, area of 2, i " elevation of '9 n.,„-. "m n ™'^*y "'■ ^y. Lindsay Russell .i :::::::::: '5 Davis, N.B., services as field assistant... I Davy lake, elevation of . . . 2 De Montigny lake.suryey by H. O'Suliivan ::::::: '5 Diabase of Abitibi volcanics, petrography of .„ see Nipisping diabase. *» Differentiation in granitic mngma Diopside, tock constituent . . '9 Diorite of Abitibi volcanics, chemical analysis of : : *"• U , " petrography of , T? occurrence of =- i- ^ ' Vi Dolomite, ferrugmous, of Abitibi' volcanics, chlni^al analysis of,.'.:: : :64* 65 a u „ ", chiomemieaof ' gg « M •< ., Ko'd-bearing deposits in IJ5 « €> „ „ not uciived from serpentine.. Rft cwcuTence of in district (^ i 126 fAon DolomiteMcrruginou^ofAbitibivolcumcs. occurrence of in PreCambiian^ ^ ori^^nor. •■.■,: 10, 65. 88, «» p.tri>Kraphy of... ■■■._„. ,„ ;; ., .. .. p„ssililv an altered sediment .05, ^.W Dolomite, (erruguious, Abitibi v;;!jMi|;|.auart. vein, in ............ ■ ^^ " rock constituent, sec carbonate. 15 DrainftBC, featuroe cl . . . . ' v. 1 1' •• pre-glacial, di«orgunuation of 19 Dufault lake, area of. 77 •• •• batholith 15 " elevation of ,:,,■.. ,^„, *f Dufn.snoy l.ko, chemical an»l.vm» of^aac^tetom-^^^.-.- •■■•■ ; j^ " elevation of _. 2 Burvey by John Bignell 19 Duparnuet lakcarca of • 122 ..' " aescription of claim on 15 " " elevation of , . 46 " " rhyo'.ito from , 121 Duahwah lake, mining claim on Eileen lake, valley of Elevation, general, of area |lli;^S'^:J^-e:a»developed in AbUibi volcanic, ;;;;;;:::::;; l^H '^ " " modeoforigm ..„ « lo m m. 71. 78. 99, Epidotp, rock constituent Evain lake, molylKlenito on. . . . Explorations, earliest of region. ; 49; 47, 49, 64, 60, 71, 78, 18 .14, 15 15 SO 55 101 120 6 Faults in Cobalt series^. • ■■ •_ 24 •' possible cause of linear valleys 29 Fauna of distiict - -. 49 54 60, 61, 62, 64, 72, 78, 101 Feldspar, alkalic, lock ^constituent, .^^-^ mieroclini, orthoclase. ^^ ^ Feldspar in auriferous quarti veins. Fenuginous dolomite, see dolomite. 30 Fish of distiict. . . • ■••■■.■ 110 Fissure system of quart* veino 114 " origin of 28 Flora of district. . . . *'' *92 Fluvioglacial deposits . .....; 68 Folding of the Abitibivocanics 87 roiu. w Cobalt senes 74, 75 Pontiao series "_[ 28, 29 Foiest of district. .. ■■■■■■■, '.'.'.'.'..'.'.'.'.'.'.'.'.'.'.'■'■ *? Formations, classification of 41 " table of • 67 Fortune lake, alt«™d quarts porphyry on 94 •^"' .. ferruginous dolomite near g " gold discovery on .64, 68 Eraser lake, ferruginous dolomite on 67 " rhyolitefrom ■.■■.:■■■■; .... 29 Fur-bearing animals, gradual extermination of 127 Gsbbro of Abitibi volcanica, petiograpby of W Galena, in auriferous quarti veins >ia " rook constituent ,„ . Garnet, rock constituent 80,67,71,72,78 Gauvin lake, batholith 77 Gillies farm, l*e des Quinse, road to 8 Glacial deposits «1. lOl Glacialonidnof Cobalt series (part) II, W. 88 Glaciation, general character of in area '•*•.?* of district 101 Gneiss, see granite and gneiss Gold, claims on Renauld lake 120 " fiist discovery in region • " on Fortune lake • " value of the deposits 12 " in auriferous quarts veins 118 Gold-bearing quarts veins, age of 118 " " composition of 118 " " " depositing solutions 118 " " fissure system of 110 ** " form of occurrence 115 " " in Abitibi volcanics 109 " " in Cobalt series 119 " " in granite 119 " " in PontJBo series 119 " " Kinojevis river 110 " " Laidet lake district 110 " " origin of 114,117,118 " " Porcupine district HO " " source cf vein material 117 Gold Belt claim, description of 121 Granite and gneiss, Abitibi lake batholith 77 " " age and correlation 82 " " assimilation of foieign material 38, 79, 80,' 81 " " auriferous quarts veins in 119 " " batbolithio masses, their general character 37 " " " " their relations to other fotma ions 37, 78. 79, 80,81 " " differentiation in 79 " " distribution 78 " " Dufault Uke batholith .7 " " Gauvin lake batholith 77 " " inclusions in 80, 81 " " metamorphiam produced by 79 " " origin of characters 79, 82 " " petrography of 77 " " Robertson lake batholiih 77 " " southern batholith 77 Granodiorite, occurrence of 78 Graphite, rock constituent 62 Grey wacke and aiKiUite of Cobalt series, character of 39, 86 Grey wacke of Pontiac series, desciiption of 72 " " distribution of 72 " " origin of 73 Uarricanaw river, canoe route along survey by W. J. Wilson Harris Maxwell claim. Larder lake, study of ferruginous dolomite from . Height of land, elevation of Hessite, in auriferous quarts veins . 5 2 66 15 ;i5 Historical geology 106 Hornblende, rock ooDstituent 47, 49, 60, 71, 72, 78, 99 128 ii li H than. Hoinblondo •chut, Abitibi voIcmIci. oiialn ol . . . "'IS " " " " p•tlo^r»phy « w " " PontUe aeriet, dMcriptioii of JJ " " " " origin ol ' j Horaetail \tke, canoo route to ■ * HudiOBH Bay Compony office™, ackoowledgincnti to « Huronian include* Cobalt seriee ~ " uiual application at term '• I Ilmenite, lock constituent *'•*••'*•*! Inclusion! in granite and gnciai J" Intorglacial deposits ;^- ■ A.ii ' i ' ' JVii-ri i Interpiovincial boundary line, niivey by O Hanly and () Uwyer ;« " Patten and Laberge 2 Iron ore, rock constituent , ;. . *^' *'• ' " " " " see also magnetite, and ilinenite. Irving, J. D., acknowledgements to • a Johnston, J. F. E., geological work by. ., j ; . , i. J i • V„ . k.^ I " survey o( parts olMakainik and Lois lakes and Lout river, by Z K Kamak hill ,15 Kame on National TranscontinenUl railway ,« 2? Keewatin, included in Abitibi group V>, 3* " previous use of term ' w KekekohJUs j* " elevation of JJ Kekeko lake, area of • •• " canoe route through » " elevation of '* " survey by John Bignel! » Kewagama lake, area of »• " " canoe route to » " " discovery of molybdenite on 6 " " elevation of 1* Kcwngama river, canoe route along J " " discovery of molybdenite on tJ Keweenawan intrusivee, characters of H " " sue NipisKing diabase. King of North lake, ferruginous dolomite near 64 Kiooievis lake, elevation of ^. _ Ij " " survey by John Bigncll Z Kinojevis river, apiitc from "• " *' canoe routes to • " " ferruginous dolomite on 84 " " quarts veins on "O " " survey by John Bignell 2 Klock's farm, Lac des Quinxe, road to 6 L Laberge and Patten, survey of interprovincial boundary, by 2 Labradorite, rock constituent W Labradorian glacier WJ Labyrinth hills ■■■ l* Labyrinth lake, survey by W. J. Wilson 2 Lao des Quinie, roads to * Lacustrine deposits, occurrence of ' }J2 " " origin of VA M 129 Lakci, araa* o( ' geaenl ehaneten o( " oriciiiairf La Mottelak*. p«iioe route to elevation of mrvey by W. J. Wilioa Lamprophyra, ot Abitibi voleanie*, chemical analyiiaof. " " " petn»raphy M 49 6 W (rmiginoua dolomite at M, N quarta porphyry (rom 87 " " " qoarUveiniat 110 La Sarre river, canoe route S " " oharaetenof IB LaurcBtian, difficulties of u*e ol term 44, 82 " previous use of term 31, 42, 44, 82 " regional distribution of 30 " see granite and Kheiss. Leith, C. K., aeknowledgments to S Linear valleys, see valley. Litboloa^, see petrography. Lloyd, Stewart J., acknowledgments to S ''^ " chemical aaalysea by 47,48,10 Lois lake, area of It " canoe route from 5 " elevation of IS " survey by J. F. E. Johnston t Lois river, survey by J. E. F. Johnston S Long lake, see Vaudray lake. Lumber, see forest. Lumbering operations in district 28 HcOuat, Walter, goologieal work by 7 Magnetite, rock constituent 48, 47, 71, 72, 78 " " " sc-j also 'fon ore. Makumik lake, area of " depth of " elevation of " " survey by J. F. E. Johnston Hap, nature ot surveys made " topographic control of Hashing of Abitibi volcanics Metamorphism by carbonation, etc " of Abitibi volcanic complei 34. " " volcaaics, mode of SS, " " " time of 65, " of aplite _ " ot gabbro, diabase and basalt " of rhyolite and quarts porphyry 48, " see mashing. Uetasomatio alteration of Abitibi volcanics " " see also metamorphinm. Meterological table, station on Lake Abitibi Mica, chrome-bearing, see chrome mica. UicTocline, rock constituent 48, 78 Mioette, peti«)p^hy of Mining operations, where being prosecuted Molybdenite, first discovery of, in region " on Caron lake " on Evain lake " Kewagama lake " Kewagama river " value ot the deposits 19 17 IS t t 2 58 65 45, 54 67, 79 " 67 88 4» 88 54 27 49 7 8 120 120 8 12 3 130 Moow, prevalence o( in dUtriet JJ Mufujovltr, rock ronilltuwit jj Muskeg, eitent o( areM o{ '• 1! NaliUKUik lake, deacrlptinn ol claimi near National TranacontinenUl Railway iUff, acknowledgment* to Niasnra strata, prpwnce ol Nickel, prenenee of. NipiMins diabase, a«a and rorreAtlon ot " " aseol " " dTstributioh . " " mode of occurrence »2, 40, •' " origin o( " " petrography of " " structural ralations North Timiskaming, road from 121 i nil 100 33 «t B8 100 88 90 • Obalski, J., geolfwical work by , , ; ^ ■ j ,. ' iJ O'Dwyer and O'Hanly, survey of Interprovincial boundary hne, by Ogima lake, elevation of ■ . „ ' l O^anly and O'Dwyer, survey of Interprovincial boundary line, by Objibway lake, deposits of " " duration of Oligoclaae, rock constituent Olivine, rock constituent Olivine diabase, see Nipissing diabase. Oiiasatika lake, area of •' " description of claim near " " elevation of " " routes to Ore-bearing solution, comiosition of im m Crthoelase, rock constituc;. ' . . , . • j r^ .. .•' 0'8ullivan, H., survey of upper Ottawa and Askowisb rivers, and De Hontigny and Pieh# lakes Ottawa river, survey by H. O'Sullivan 7 2 IS 2 104 104 M 99 19 121 IS 8 US 71,78 2 2 r Palaeosoic strata, presence of ^^' S Palaeoioic submergence of region » Paleoplnin of Timiskaming basin '''• "S Parks, W. A., geological work by . , , , . Patten and Laberge, survey of Interprovincial boundary by - Pegmatite dykes, . '• Peneplain, presence in area. •; , ia ol' S " " over Prc-Cambrian area »<>. 24, liH Petrography of amphibolite, Abitibi volcanic* S9 " " Pontiae series <2 " amygdaloidal structure 80 " andesite, Abitibi volcanics « " aplite SS^ Ji " assimilation by granitic magma 38, 79 " basalt, Abitibi volcanics J9 " biotite schist, Pontiae series 71 " chloritic rocks, Abitibi volcanics •• " dacite, Abitibi volcanics « " diabase, Abitibi volcanics 49 " " (Nipissing).... JJ " differentiation in granitic magma 79 •• diorite, Abitibi volcanics 46 131 r«ui. M. tS 64 49 77 77 M 71 W M 4» W 77 A2 71 67 4A 67 n HI 43, Petrognphy o( pHi(»oM»l »«nirturo . . ■ , " (erruKinoua dolnmitp, Abitibi volrmska. " Rkbhro, Abitibi volonlos " gni-iKii iind grenili" " minitr ami gnciiw " hornblpnde •chli-t , Abitibi volrank** " " I'ontlsc nerini " Ikmprophyre, Abitibi volpanim " inotamorphiam o( A bitlbl volrsnlr* " minrtta " NipiMinc diabaw " peRmatite pliylUt* and alate, Abitibi KToup Ponliacieriea • • " quart! porphyry " " " and rhyolitc, Abitibi voiranici rhyolit* BcMiita and araphibiilitM, Abitibi volcaaira " wricite ichiat, Abilibl volraaica " ayenite porphyry lUO Pptiilf, in Buriforoua quarti vclna 1 16 Phyllite and alatc o( Abitibi (troup 62 " " " " chaiarterot 6J " " " " diatribution o( M » •• " " origin of 63 " " " " atnictural relation dt 62 Phyaical (eatures, dovription of 13 Pich« Ukc. aurvey by H. O'SulUvan 2 Pillow KtruPtuke, am ellipaoidai atructure. Pine, Banksian, occurrence of M " white and re " " of Pontine scries 73 Serieite, rock constituent 46, 47, 49. 80, 54. 6t, 62, 64, 66, 67, 71, 78, W, 101 SericitescbistolAbitibi volcanies, occurrence ol SO " " " " of possible sedimentary origin 62 origin ol 61,79 petrography ol Serpentine, not the source ol the lerrugiDnus dolomite. Shiminis mountain, description ol " " elevation ol SUicification of Abitibi volcaiaics Sills, C. P., services as field assistant Silurian outliers, explanation ol presenre " " occurrences ot Simpson, A. C, services as field assistant 61 68 14 IS 55 3 22 33 3 133 rtor. SUtcMil phyllite, o{ Abitibi i;iiMip «3 " " •' eh»nip4«ir a( S2 * •• '• Uiatribulloiigl W " " " orWa of 63 " " " utructunl rcbitlMu of «2 HmokyhilU M Houthera batholith 77 Hphmxi, rock eonaiitucnt 47. 4*, 80, 60, 71, 7}, 7S, 101 Spirit lake, rlevatiiHi of t.'j flpnira, blark, orrurrnnre of jjn Htowart, J. H., ncrvim m fl*td waiftaat i, 3 Htraam eBptttn>, eumpio of |( HtruoturBl f>«turM of the Abitibi votcuici M Stnietumt cedosy 106 Hurvcyiag methodi •dopted 2 Hurvey • m>de uw of , j HwiBgiiMi hilli 14 " elevation ol IS Myanite porphyry, orcurronre of 40,100 " '' petrography of 100 " " itruetural feature* of 101 Tamarack, deatniction of 28 Tenendo hilU \S Thermal replaoement, orisio of femigiBous dotomite by 60 Thiekoen of Cobalt lerien 84. 87 " Pontiae leriea 76 Timber, lee foreat. TimiskaroinK baain, phyaioarHphic hixtory of 20 Timiikaming lake, depth of 21 " " description of 21 " " elevation of 21 " " ori•'• — ^"•^iSwOl*''*.". 1 .„d Skeena ^'•il^in. divi^on.. Skeena ^^^^^^ ^^ ^^ ^^^, „.„.. ^'•- ^ndary di.trict. B.C. BV ^^^ ^^^^.^, ,„d • !l Senn- it. E. Wilaon. . .„ _.^ Routtemont, «■ ^- ^'^- ,, Hilaire (Beloeil) and Bougemont. ^ moi^ntiunB.Que*^- »> ' . .„„_ Brunswick. _. J .hale vo9r,OeoIo(H«aS«n«.. CUy an " ByJ. Keele. „_ni -Mnloolm. ^"syJ. K****" „ *• nvW. Malcolm. La 8^ Gold fidd.0. Nov. Scotia. ByW. '"'*^ B.^ o. Chu^UiU -Id Nel«n river.. By W M Mmioir 41. .Vu. M, 0'roJuu/ca< Utri'o. The "Fern Ledgtt" CwboniCrrouK Kara oi Ht. John, New Brunxwink. By Murie C. Stopes. MmoiH 47. titologiaU tic-M. Clay itnd ahale dopoaiU of the wratern provincm (Httrt III). By Heinrioh Kiew Mkmuik4J. .Vu. /, Antkropologiml Arrita. The double-curve motivi! in north- rniitorn Algonkian art. By Frank U . Speck. Memoik 48. .Vu. f, AttAropoloQieal Sena. Home myths and tales of the Ojibwit <>f southeastern Ontario. Collected by Paul Radin. .Mkuuir 45. .Vu. S, Anthropoloiiicol .Scrim. The inviting-in feast of the .\laska I'^skiiiio. By E. W. Ilawkeii. reen f3. istein ,. By Skeena sU. mines, nes and ch map- jec. By .ugemont, Itunswick. i»lm. ,. By W. 40691— 10 )t I h I V "^n^ % m ■ r 5 ? 40591-A ■- fl 40W1-Ai llJ: ^^1 l>3 1 t I i M i I ■8 1 ! \ : V 1 dtt f 'J t-i.f I o i 3 2 "i i J 1,5 I I t ^ i- X s « ■s 8 •g a L f I » I!;: T > 1 ■g O •> H I ■* I'U Hi It m s iii- Fun IX. Photomicrograph showing eutaxitic stnicture in a baaalt flow occurring on the portage from Dufresnoy to SilU lake. Ordinary light. Magnified 20 diameters. I|.r t. i I 4 I I s I .9 I Plati XV. Photomierogrsph of tourmaline in quartz, from veinlct traversing terraainous dolomite, oceurrinK on Mackeniie lake, Privu township, Abitibi district. Que. Croescd nicols. Magnified 2C diameteri. PlatiXVI. jr >'-'--;»"^. ~ ■■!- _j, , .f. •.» -.. ■'■::^"^:w>^^^' Photomirraara|>h o( the givywacke o( the Pontiac aeries, occurring on Clericy lake. Pontiac county, Que. CroHsed nicola. Mas- nified 20 diameters. Compare witti Pbttii XVII and XVIII. PiATt xvn. Photomicrograph of the RreYwacke matrii o( the ronxlumerate r>f the Pontiac wrien ocnurrinK on the Kinnjevis river. Crowcil nicola. Magnified 20 diametera. Note the purtial recryntallii- Btion and conipare with Plates XVI— the original greywacke — and Plate XVlII, the end product o( recrystalliiation. I»IA« XVIII. Photumirrocraph ol the Pontiac schiat occurring on Kekfko Uke. Crxnaed nicola. Macnified SOdiamctera. 406«1- MKIIOCOPY IBOUniON TBT CMAIT (ANSI gnd ISO TEST CHART No. 2) A /1PPLED IIVMGE Inc ^p^ 16S3 Eost Moin Strtet S'JS Rochester. Htm York 14609 USA ^^£ (716) 482 - 0300 - Phon« ^S (716) 280 - 5989 - Fax h i 4(B91-c} w^- i:] lis I X I I* i i! II I- 8« P .§1 ii ■a • Hi '•"! s ! ii 11 i I ■S-l 1 II .Is" ■31 If I' .3-S 3-S 11 PUTB XXII. Photomicrograph o( the matrix of the baaal conglomerate of the Cobalt series occurring on the south shot« nl Lake Daaserat. Ordinary light. Magnified 20 diameters. I s«^3r .■ • %\: Pun xxm. t.'^:;.«*;»^-^^^^:^ Photomicrop»ph of the matru o* the bawl conglomerate ?i i^* 1 "i?" ??"*''• .oeeur™* on the south ahora o( Daaent Uke. Crowed nicoU. MagniBed 20 diatneten! II IF II 11 ■i 1 li if i 1 If 1 WM^f i. 'f ! .Ja ?'■, ' ;i ^ hi ■f. ii 4osgi— D # t I 1^^' i »§• I' ^8 I i 1 -8 -a 8s& Is"? oaii -! H .. . . 1. 1 If >ii i GCOIOGICAL RECONNAISSANCE LrUiKNO «r«'KlN*WAN >ll|tll>mu{tnaiia flnldiuitf • JtJofUtr rui iim. uMwAiA'f Svuilml*- fifolntfical fxnttuliirv fwifan lirt'tnni I n hkn:^ ^ "" "• HoMlCooiMMi MiktriN APlowDcnitYMiMitTM OIOiOOICAi tURVCV oeoGf I («>**|w|f|ft|| IhkhwIiii-^ i *Pi>liH|U' « O N T « K TJ I L " " ^ l /M*^ K ' i'^ ^ j ^ H— »t- 7*»W ('0*M^Mirnl , lit^Htrtiptu^ fimtt i'tf4' htttuJtklnm.i J' «i MAI' »»;iA KEWACSAMA ABITIBI AND PONTIAC Siiilf 'j.vi.44a Mili-n CCOLOOV mj WILS9H m.twiLSom m/i»t s Mtic rnffirus.^oiuc OeOGRAPHV J f t.jOMt/srofi wj wuseff Mi wtlSOM Duv^mem cr coiomturioii. mimis am nsHti- k t-ir otntmTMtMT or lamos amd fomsTS.OMUC Amcinee» .„„„, .' Si. 4 MILCS TO I INCH GEOGRAPHICAL B/j RATED GBADE 3 Ti