KENSINGTON AREA, GATINEAU and LABELLE COUNTIES Honourable C.D.FRENCH,Minister

RG 050(A) KENSINGTON AREA, GATINEAU AND LABELLE COUNTIES Honourable C.D.FRENCH,Minister

:,ri:VICE DOCUMENTATION TECHNIQUE GATINEAU AND KENSINGTON AREA GEOLOGICAL REPORT PROVINCE OFQUEBEC,CANADA GEOLOGICAL SURVEYSBRANCH E. PRINTER TOHERMAJESTYTHEQUEEN Aubert Department ofMines 1. RÉDEMPTI W. JONES, QUEBEC by LABELLE 1953 de laRile PARADIS Chief A.O. DUFRESNE,DeputyMinister COUNTIES 50 ~

TABLE OF CONTENTS Pane Introduction 1 Location and area 1 Means of access 1 Acknowledgments 2 General features of the area 2 Topography 2 Drainage 3 Population 5 Resources 6 Previous work and bibliography ,... 8 General geology 8 Table of formations 9 Grenville series 9 Limestone 10 Quartzite 11 Amphibolite 12 Metamorphic pyroxenite 13 Paragneiss 13 Migmatites 13 Intrusives of various types 16 Granitic intrusions 16 Kensington syenite 19 Other syenite, monzonite, and diorite intrusions 21 Gabbro 22 Basic dykes 23 Pleistocene and Recent 24 Structure 25 Economic Geology 26 Zinc 26 Magnetite 28 Molybdenite 28 Graphite. 28 Muscovite 29 Phlogopite 30 Chrysotile asbestos 31 Quartz 31 Garnet 31 Building materials 31 Conclusions 32 Alphabetical index 33 ILLUSTRATIONS maps Map No. 919 - Kensington area, West part (In pocket) Map No. 920 " " East part n "

Plates Plate I Thirty-one Mile lake from the west. The hills overlooking the east shore in the background are in Wabassee township. Plate II• Roddick lake, Cameron township. "Montagne de Fer" (Iron Mountain) on the left. Plate III A.- Gatineau river, looking upstream from Corbeau rapids (Kensington. township). The escarpment of crystalline limestone is cut by diorite. B.- Limestone bluffs along the left side of Gatineau river (lot 60, range III, Cameron township). Plate IV A.- Interbanded limestone and pyroxenite. On the shore of an island in Thirty-one Mile lake (Wabassee township). B.- Solution effects in limestone. West shore of Thirty- one Mile lake. Plate V A.- Banded gneisses (migmatites) along the west shore of Thirty-one Mile lake (range VII, Cameron township). B.- Quartzite beds at the outlet of Léveillé lake (range VI, Cameron township). Plate VI A.- Garnetiferous paragneiss, east bank of Liévre river (lot 12, range I, Dudley township). B.- Banded paragneiss, Bouthillier township. Plate VII A.- Banded garnetiferous paragneiss (lot 18, range V, Dudley township). B.- Small fault in Grenville paragneiss (lot 44, range VII, Bouthillier township). Plate VIII A.- Pyroxenite inclusions in Grenville limestone lot 11, range V, Dudley township). B.- Folding and injection of granite in paragneiss (lot 16, range IV, Dudley township). KENSINGTON AREA

Gatineau and Labelle Counties

by E. Aubert de La Rfiex

INTRODUCTION

Location and Area

The report that follows deals with the geology and mineral resources of the Kensington area of the western Laurentians, in Gati- neau and Labelle counties. The work on which it is based was carried out during the summers of 1943 and 1944.

The area forms part of the regions covered by sheet 31 J (SW) (Maniwaki) published by the Dominion Topographic Service on a scale of two miles to one inch. It lies between latitudes 46°15' and 46°30' North and longitudes 75°30' and 76°00' West, totalling 414 square miles in extent. Kensington township is at the centre of the area, which includes also almost all of Bouthillier township, the southern half of Aumond and Robertson, the northern part of Cameron and Wabassee, the eastern parts of Egan, Maniwaki, and Bouchette, and the western part of Dudley.

The above mentioned topographic map, enlarged to a scale of half a mile to the inch, was used as a base map. Traverses were run in general at intervals of one mile and were even more closely spaced in some localities. The shores of all the principal lakes, which ordinarily afford many outcrops, were followed by canoe. Aerial photographs of the region, made available through the courtesy of the Royal Canadian Air Force, furnished useful information.

Means of Access

The Kensington area is easily accessible both from the east and from the west. From Montreal the area may be reached via the Canadian Pacific Railway branch line that terminates at Mont-Lau- rier, five miles from the northeast corner of the map-area. Route 25, the Senneterre highway, passes through the eastern part of the district, affording an easy means of travel from Mont Laurier, the county seat of Labelle county, to Buckingham, ninety miles away. The western

Translated from French. - 2 - part of the area is served by the Canadian Pacific rail line that follows the Gatineau valley from Ottawa to Maniwaki, the county seat of Gatineau county. The section of the Hull-Mont-Laurier highway (route 11) between mile 75 and mile 100, approximately, runs through the district and passes through Maniwaki, which, by this route, is 85 miles from Hull and 200 miles from Montreal.

There are numerous secondary roads in the settled western and eastern parts of the area; only the uninhabited central part is completely lacking in roads and, as a consequence, difficultly accessible. There is no direct route from west to east across the area so that to go from Maniwaki to the Lièvre River valley, for example, it is necessary to travel via Mont-Laurier and make a circuit of about fifty miles, although the straight distance through the bush is only about twenty miles.

Acknowledgments

Romeo Morin of Sainte-Thérse-de-Gatineau acted as assist- ant during part of the 1.943 field season and Jerome Lachance of Ples- sisville and Jules Hurtubise of Notre-Dame-de-Pontmain served succes- sively in a similar capacity in 1944. Their work was very satisfactory.

The writer takes this opportunity of recording his thanks to Messrs. 'Foster Bennett and Armand Dion, of Maniwaki, who kindly placed at his disposal thé camps which they own respectively on Kensington lake and Quinn lake.

GENERAL FEATURES OF THE AREA

Topography

The country has the topographical features typical of 'the Laurentians' -- an ancient, eroded plateau dissected into numerous ranges of hills that follow no apparent pattern. Between the hills are a great many lakes of irregular outline and very varied size, as well as alluvial plains which are generally narrow, long, and in many cases very sinuous. Such plains are especially numerous in the eastern and western parts of the area and are, for the most part, old lakes or stream channels filled in with glacial, fluviatile, or muskeg deposits. Swamps and clay form the surface of these low- lying belts. However, on a large tract in the southeast part of the map-area these former plains are now submerged beneath the waters of the Dudley reservoir which was formed by damming Lièvre river at Notre-Dame-du-Laus in 1930.

The largest single plain, in Bouthillier township, trends -3- northeast-southwest for eight miles and has a maximum width of three miles. It extends from the west shore.of des Isles lake to Pearson lake (or lac des Ours as it is known locally). This is an important pre-glacial drainage channel which will be discussed, in a later para- graph. The northern part of the plain, termed the 'Valley Range', is settled and farmed and forms part of Lac-des-Isles parish. The middle part is• a marsh known locally as the 'Grande. Marsh'. -

The plains and the principal lakes are between 500 and 700 feet above sea level, the lowest being in Cameron township. The hills, which have gentle slopes, have elevations ranging from 900 to 1,600 feet above sea level. Thus it is seen that the area here discussed is one of the less elevated portions of the Laurentians. The most hilly and rugged part is a little east of the centre of the map-area, where a north-south belt of hills forms the divide'between the Gati- neau drainage on the west and the Lièvre grainage on the east. The divide, which follows a sinuous course through the western part of the townships of Robertson, Bouthillier, and Wabassee, attains its greatest height between the valley of Lièvre river and Thirty-one-Mile lake. Here there are elevations in the order of 1,250 to 1,600 feet above sea level. Parallel to, and on both sides of, this height-of- land are other ranges of high hills, as for example west of Quinn lake, east of Achigan lake, and especially east of the valley of Lièvre river immediately south of Notre-Dame-de-Pontmain village, where an isolated prominence known locally as 'Montagne de la. Tour' (Tower mountain) rises to 1,630 feet. A forestry observation tower on this "mountain" (lot 13, range II of Dudley township) affords an excellent view of the surrounding country. This hill is one of the most prominent landmarks of the map-area. It is exceeded only slightly in height by some hills north of Babiche lake, which rise to 1,650 or 1,700 feet.

The hilly district, rugged and with steep slopes, in the central part of the area, owes its development to the presence of a considerable body of granitic gneiss, a rock especially resistant to erosion.

Drainage

About three-fifths of the area is drained by Gatineau river and its tributaries. This mighty river, the middle portion of which flows through the western part of the area, has for more than a century been of major importance in the driving of timber. The remaining two-fifths of the area, that is the eastern part, drains by way of Lièvre river, which is considerably smaller than the Gatineau.

Both rivers flow due south and at their closest approach -4- to one another are only about twelve miles apart. Gatineau river follows a generally straight course and has carved a relatively narrow valley, so that in many places it flows between steep, rocky banks. Its bed is irregular and in places is very narrow and impeded by rock ledges, features that give rise to numerous rapids. Along this narrow stretch there are several islands, both of rock and of fluvial deposits. Where the valley widens, even though only a little, especially in the north near St-Joseph lake and above and below Maniwaki, its banks are formed by clay terraces with here and there a rocky butte of Precambrian rock projecting through the clay.

In that portion of its course within the present map-area, the Gatineau is joined from the west, in the town of Maniwaki, by Desert river, a slow flowing and extremely sinuous stream. The principal tributaries entering from the east are Joseph river and Post creek. Most of the drainage basin of- the former, which has a very winding course, lies within the map-area. Post creek-, which joins the Gatineau farther downstream, is short but important, for it is the discharge of a chain of lakes, one of which, Thirty-one-Mile lake, is the largest in the region. This lake and the others of the chain that lie downstream from it (Michel, Léveillé, Lochiel, and Roddick lakes) have green, very clear water in contrast to the deep brown water of some Laurentian lakes, whose bottoms are commonly formed by a thick deposit of flocculent, blackish mud. There are also a few lakes in the eastern part of the area whose waters are remarkably clear and green; for example, Babiche, Ladouceur, and Grand Cerf lakes.

Lievre river, after just touching the northeast corner of the area, five miles south of Mont Laurier, swings into the map-area near Wabassee and cuts across the southeast corner. In 1930, a dam built at Notre-Dame-du-Laus raised the level of the river about 15 feet, and established a control reservoir for regulating the flow of the river below. As a result, the bordering low-lying terrain was flooded and a complicated network of artificial lakes now lies between the villages of Lac-des-Isles and Notre-Dame-de-Pontmain.

Among the tributaries of the Lièvre should be mentioned, on the east, Cerf creek which drains the two lakes of the same name, and, on the west, Lac des Iles river and Paquet and. Pearson creeks. The last named heads in several small lakes in Robertson township and also drains most of the lakes which lie within the extensive plain in ranges VII to X of Bouthillier township, already mentioned. It is interesting to note, in connection with this plain, that it is a section of an important pre-glacial valley that the writer has previously - 5 - identified farther north, in the Sicotte map-areal. The valley in question enters the Kensington map-area at. the northern end of lake des Isles, with which it coincides in part, and joins the valley of Lièvre river at the outlet of Camp lake, in the centre of Pontmain village.

There are more than two hundred lakes within the map-area. Some are merely shallow ponds in the midst of swampy plains. Most of them, however, are of glacial origin, some of these owing their origin to the damming of waters by moraines, others are in depressions gouged by the ice in the limestone areas. Lakes of the latter type are the more numerous. In the Lièvre River drainage basin, the most prominent are lake des Isles, six miles long, Big and Little Cerf lakes, Camp lake, and Dudley lake. In the Gatineau basin, the most important are Murray, Achigan, Kensington, Boisfranc, Beaulieu (Dan's), Michel, and Roddick (Rond) lakes.

The elongated shape of some of the lakes - such as Quinn lake and Thirty-one-Mile lake, which is said to be very deep - which occupy glacially scoured depressions is doubtless a consequence of the structure of the underlying rocks.

In concluding tais review of the drainage system, it is of interest to mention the existence of several small, partially subterranean streams in certain belts of limestone within the area. A good example is the outlet of a small lake in the centre of lot 17, range -XI of Kensington township. This brook disappears for a distance of about half a mile, then reappears near the south shore of Kensington lake. The small lake in range VII of the same township, just north of Noire (Black) bay, has been named Pont de Pierre (Rock Bridge) lake, for its outlet has carved a channel beneath a huge limestone arch.. Springs of excellent drinking water issue from the Grenville limestone in lots 7 and 8, range B of Aumond township, near what is known as the River road between Maniwaki and Ste-Famille. There is another spring of the same type in lot 41, range III of Bouchette.

Population

The area has a population of about 6,500 - 5,000 in Gati- neau county and 1,500 in Labelle. French-speaking Canadians greatly- predominate. Canadians of Irish descent, living around Maniwaki, make up about one-fifth of the total. There are, besides, a few hundred Indians on the Algonquin reserve at Maniwaki, of which only a part lies within the map-area.

1 E. Aubert de La Rae, Nominingue and Sicotte Map-Areas, Labelle and Gatineau Counties; Que. Dept. Mines, Geol. Rept. 23, 1948. -6- Maniwaki, situated at the confluence of Désert and Gati- neau rivers, is the lar9est settlement in the area, with a population of 2,360 according to the census of 1943. The town owes its importance to the lumbering industry and houses offices and stores of the Canadian International Paper Company, which holds large timber limits in the surrounding territory and especially to the north, in the upper Gatineau valley. Maniwaki is also a very active trading centre where the farmers of the district come for their supplies and to sell their produce. Other settlements in the western part of the area are the villages of Ste-Famille-d'Aumond and Ste-Thérbse-de-Gatineau, with 922 and 720 inhabitants, respectively. The latter settlement dates only from about 1933. In addition, there are. three smaller hamlets: the parish of Bois Franc in the north; that'of Souchette in the south; and the third in the vicinity of Ferme Joseph, in Kensington township.

There are three centres of population in the eastern part of the area: the villages of Lac-des-Iles, Notre-Dame-de-Pontmain, and Lac-du-Cerf; this last is in Dudley township and was founded only recently. These small farm centres are in the Mont Laurier district and have no direct communication with Maniwaki.•

Resources

The greater part of-the'area covered by this report is heavily forested.. Despite a -century of exploitation during which enormous quantities of red and white pine have been logged, the lumber industry is still prosperous.

The central highland, which is not suited for settlement, still has important reserves of timber. These stands which,west of the watershed, form part of the timber limits of the Canadian Inter- national Paper Company and, in the basin of Lièvre river, are owned by the James MacLaren Company, consist of hard woods (white and yellow birch, ash, elm, beech, etc.) and several fine groves of hemlock. On the lower ground these hard woods give place to balsam, spruce, and cedar. Most of the cut of soft wood is 'driven' down the Gatineau to Hull or down the Libvre to Buckingham; the aspen, which is cut for pulpwood by the farmers on their own lands, is shipped by rail. Ten sawmills were operating in the map-area in 1944, the most important being the Strong's mill, at Cameron (Michel) lake. Several portable mills were also in use around Maniwaki, handling, for the most part, pine for local use.

From time to time in past years, destructive forest fires have spread over various parts of the district. The last major fires occurred in or about the year 1920.. One of these, in Kensington township, ravaged an area a few miles eastof Maniwaki which still bears the name 'Grand Brulé' (the Big Burn). Another burned large areas of forest in Robertson township between Quinn.lake and lake des Iles; and the southeastern part of Bouthillier township and the western part of Dudley likewise suffered severe fire damage.`; It is now very difficult to travel through these old burns.

The area is now in the transition period between a lumbering'and an agricultural' economy. -The oldest' farms in the valleys of the Gatineau and Lièvre rivers' were established about.eight'years ago. Clearing of ground has been actively pursued since that time and cul- tivated lands now cover a fair extent both'on the alluvial. river flats and on the hillsides,'especially around Lac-des-Iles and Sainte-Thé- rbse-de-Gatineau.

The chief garden crops are potatoes, turnips, and carrots, but, for raising cattle, oats, buckwheat, and corn are produced in important quantity. Other produce marketed includes butter, pork, and poultry. - There is some production of maple syrup products. On many of the farms, sheep are raised. Today, few of the people living in the area engage in trapping.

- Only a small part of the potential hydroelectric.resources are at present utilized. A few falls have been harnessed to provide electric power. for local needs. Two of these are on Joseph river. One, with a head of 16 feet, supplies 40horsepower for Mr. Filion's sawmill, which is located east of Ferme-Joseph (Kensington township) and is known as 'Moulin de la Grande Pointe'. The other, a fall of 12 feet, is at Sainte-Famille-d'Aumond, where 110 horsepower is developed for lighting the village and operating the adjacent sawmills of Messrs. R. Alie and R. Guérette. Dubé's sawmill at Lac-des-Iles uses an 18-foot fall at the discharge of the lake, and the Bondu sawmill on Pearson creek is driven in the same fashion.

The Gatineau Power Company operates a generating plant at Corbeau Rapids, five miles below Maniwaki, where the west branch of the Gatineau has a fall of 16 feet and provides 2,500 horsepower for lighting and power supply in Maniwaki.

Plans have been under consideration for the building of a dam and power plant of larger size farther downstream on the Gatineau, at Cheval Blanc (White Horse) rapids, near Bitobig Lake post office.

There are picturesque localities in the central part of the area, notably in the vicinity of Thirty-one-Mile lake, where hunters come from Hull and Ottawa in the autumn. In Libvre River valley, Notre-Dame-de-Pontmain is a fairly popular small summer resort. The same is true of lake des Iles and Big Cerf and Little Cerf lakes, which likewise attract some tourists in summer. -8 -

PREVIOUS WORK AND BIBLIOGRAPHY

The Kensington map-area is adjoined on the northeast •and north, respectively, by the Nominingue and Sicotte areas which were mapped by the writer in 1939 and 1940.

The only previous detailed geological work in the area itself is that of M.E. Wilson who, in 1918, mapped an area of about 40 square miles around Maniwaki. Notes on the geology and concerning mineral occurrences are to be found also in the earlier reports listed _below. It should be mentioned, also, that the work 'Le Nord de l'Ou- taouais' by Father Taché contains some information on the geography and economics of the area.

(1)Bell, R., Geol. Surv. Can., Ann. Rept., Vol. III, 1887-88, pp.25- 26A. (2)Hoffman, G.C., Geol. Surv. Can., (New Series) Ann. Rept., Vol.XII, 1899, p.25R. (3)Schmid, Hugh S. de, Mica, Its Occurrence, Exploitation and Uses; Mines Branch, Dept. of Mines, Ottawa, 1912, p. 129. (4)Keele, J., Northern Portions of Pontiac and Ottawa Counties, Quebec; Geol. Surv. Can., Sum. Rep., 1916, pp.219-227. (5)Wilson, M.E., Arnprior-Quyon and Maniwaki Areas (Ontario and Quebec); Geol. Surv. Can., Mem. 136, 192+, pp.120-136. (6)Geological Traverses in Labelle, Papineau, Argenteuil Counties, etc.; Report on Mineral Operations in the Province of Quebec, 1928, 1929, p. 200• (7)Taché, Rev. P.L., Le Nord de l'Outaouais (396 pp.); Ottawa, 1938. (8)Aubert de la Rue, E., Nominingue and Sicotte Areas, Labelle and Gatineau Counties;.Que. Dept. of Mines, Geol. Rept. No. 23, 191+8.

GENERAL GEOLOGY

The Kensington area is underlain by Precambrian metamorphic and intrusive rocks which outcrop abundantly throughout its extent. Precise delimitation of the several types of rock represented is, however, difficult, for clear-cut formations with sharp contacts are rare in these ancient rocks. This is true, not only of the map-area here dealt with, but of many other districts in the Lauren- tians.

The oldest rocks belong to the Grenville series and are much altered sediments of various types. These are cut by intrusive rocks, chiefly granites and syenites, more rarely diorites, and in places gabbros and ultrabasic dykes. The distinctive intrusions outcrop in relatively restricted areas and were emplaced at several

-9 - different times. It is not always possible to work out the exact order of this succession for they are rarely found cutting one another. As a consequence they are here classified according to their lithology without attempt to group them into series of intrusives, as has been possible in some other parts of the Laurentian region.

The Pleistocene is represented by unconsolidated superficial deposits that are especially widespread in the east and west parts of the area. In general, their thickness is not great, in the order of 60 feet, but they are doubtless thicker locally in some of the old lake basins.

Table of Formations

Fluviatile and lacustrine deposits Quaternary (gravel, sand, mud, and clay) Glacial and fluvioglacial deposits (moraines, eskers, sand, and gravel)

Great Unconformity

Basic dykes Intrusive Gabbros and associated microgabbro dykes Rocks Syenite, monzonite, and diorite, mica- rich and generally fine grained Kensington syenite Granites of various types, commonly Precambrian gneissic; associated pegmatites Migmatite Grenville Crystalline limestone, garnet and sil- Series limanite paragneiss, various other paragneisses, quartzite, amphibolite, pyroxenite

GRENVILLE SERIES

Metamorphosed sedimentary rocks of the Grenville series underlie, at least three-quarters of the map-area. It seemed expedi- ent in mapping these rocks to group them in two main divisions. This subdivision has no chronological significance. Lithologically, however, and often also in topographic expression, the works of one group are very different from those of the other. One group is made up of limestones, quartzites,. and well-bedded gneisses, the two last named with their original stratification well preserved, and more rarely amphibolites and pyroxenites, rocks whose metamorphic character is indubitable. The rocks of the other group are migmatites, - 10 that is, paragneisses that have been so strongly granitized.that, in some places, especially where exposures are small and isolated, it is difficult to determine whether the rock is paragneiss or orthogneiss. However, where migmatites are exposed in relatively large bodies, their peculiarities such as ribbon-banding, heterogeneous texture, and the presence of ptygmatic folds, and their garnet content, render them easy to recognize.

Limestone

There is a large belt of Grenville limestone in the eastern and southeastern parts of the map-area, underlying, in general,. the low-lying ground. The basins of the principal lakes are mostly developed in limestone, as also are the valleys of Lièvre and Gatineau rivers.

The crystalline limestone is a light coloured rock, generally white to pale grey when freshly broken but invariably grey on the weathered surface. Pink or reddish varieties are occasionally 'found, and rarely the rock has a blue colour, as for example on the left bank of the Gatineau, opposite the south end of Corbeau island. In many occurrences the limestone exhibits ribbon banding, but this structure is not an original one and seems to have no relationship to the bedding. The stratification is no longer discernible because of the complete recrystallization of the rock and the effects of the pressure to which it has been subjected; in fact, during the processes of metamorphism, the rock acquired such.a degree of plasticity that, in some instances, lenses of limestone were squeezed between gneisses and appear almost as if they had been intruded into the latter. This feature is well developed on the north shore of Camp lake.

The Grenville limestones differ greatly in appearance from one place to another due to variation in grain size, which may be extremely coarse. The many outcrops along the Mont Laurier- Buckingham highway one mile south of lake des Iles are remarkable in this respect. Their appearance varies, also, with the amount and type of accessory minerals they contain, either disseminated or in aggregates which are often much contorted and crumpled. The most common of these are diopside and other calcic silicates, phlogopite, feldspar, quartz, and graphite. Worthy of mention also is the occasional presence of small octahedra of spinel, often accompanied by chondrodite, as for example in thelimestone exposed in front of the church at Ste-Famille d'Aumond, and in .the escarpments in lot 35, range I of Kensington township.

Besides these accessory minerals, the limestones in places contain inclusions of a variety of rocks, such as gneiss, granite, and gabbro. - - 11 - Because they are more resistant to erosion than the calcite which forms the body of the rock, the inclusions of foreign material commonly stand in relief on weathered exposures.

Sink holes are quite common in the limestone belts. Also, along the shores of some of the lakes, as for example des Iles, Big Cerf, Achigan, and Thirty-one-Mile lakes, the limestone is pitted in a peculiar manner. Usually, the pits occur as a great number of small cavities of conical shape and with a circular opening. They are of all sizes, but the most common are one to eight inches in diameter and four to five inches — some up to one foot — deep. In places where they are very closely spaced, the wearing away'of.the narrow rims between them has left a surface pitted with a vast number of tiny cup-shaped depressions. The pits, which occur only at the water's edge, are found to a height of three to five feet above lake level and also in some instances to three feet below it. It thus seems that they are localized between high and low water level. It is reasonable to suppose, therefore, that they have been formed by selective solutions of the limestone in the course of repeated splashing by the lake water, but the reason for their very irregular distribution is not known. They are abundant in some places and absent in others. It seems strange that these hollows are especially numerous where the limestones are most homogeneous. Independent of this pitting, but sometimes found in the same place, are parallel, more or less closely speced grooves, between which there may be sharp, narrow ridges. These furrows are perpendicular to the shore line and widen away from it. They seem to, be the result of the combined ac- tion of splashing and trickling water.

Quartzite

The quartzites are grey, glassy-looking rocks which only rarely consist of quartz alone. Generally, they contain feldspar — which may be kaolinized — and mica, and in many occurrences graphite or garnet, or both these minerals, are present. In the western part of the map-area, the quartzites are of minor development compared to the limestones and gneisses, in the midst of which they occur as bands of various thicknesses or as interstratified beds. In some places they are highly granitized, but even so they have retained their bedding planes. Such rock, with associated migmatite, occurs in a well marked chain of hills in range II of Egan township, about two miles south of Bois-Franc. Feldspathic quartzite that outcrops on some of the islands in, and on several points along the shores of, Thirty-one-Mile lake bear a marked resemblance to fine-grained, light-coloured granite. - 12 - Finely pyritic quartzite with rust-coloured weathering forms.a steep-sided hill, known locally as "Iron Mountain", on the north shore of Roddick lake (range III, Cameron township).

The quartzites have a wider distribution in the eastern part of the area. There, their main belt of outcrop is a fairly long and uniform band forming a line of hills that extend from Bouleaux lake to a little west of Lac des Iles village.

A few beds of magnetite-bearing quartzite are associated with gneisses on the escarpments that face the west shore of Pearson (Ours) lake, in lot 41, range XI of Bouthillier township, and a similar rock is found in range IIN of Wabassee, at the end of Long bay, an arm of Camp lake. At the latter locality there is a good natural section showing repeated alternations of garnet paragneiss and magnetite-bearing quartzite, and several zones of pyroxenite (containing phlogopite and apatite), the whole well and regularly bedded and dipping steeply toward the north. A few small veinlets of granitic material cut the whole assemblage. This section is especially remarkable in that it shows how little these quartzites and gneisses have been disturbed despite the intense metamorphism to which they have been subjected. They have simply been upturned without the development of the close drag-folding characteristic of so many other localities,. and they have retained to a marked degree their original stratification.

Amphibolite

Amphibolites are fairly common in the western part of the area. They are associated with the crystalline limestones and occasionally with the paragneisses. There is no indication that they are derived from basic lavas or tuffs rather than from highly magnesian sediments. In general, they are massive rocks, without schistosity, and in places they have a very coarse texture. Besides the predominant green amphibole these rocks contain plagioclase, biotite, sphene, apatite, and epidote. Although the amphibolites are quite abundant they do not generally outcrop over wide areas, except in ranges II and III of Kensington, especially between lots 4 and 12. There are some outcrops, also, along the Maniwaki-Ste-Thérbse highway.

In the eastern part of the map-area, the amphibolites occur under very different circumstances, being in almost all cases closely associated with granitic rocks which are here considered as being migmatites and which will be discussed on a later page. - 13 - Metamorphic Pvroxenite

Metamorphic pyroxenites, composed essentially of diopside but often of very heterogeneous appearance, form numerous outcrops which, however, are generally of small extent. They are closely related to the other formations of the Grenville series. Ordinarily, they contain a fairly large amount of pyrite or pyrrhotite which oxidizes and gives the outcrops a rusty appearance. The pyroxenite zones, apparently more numerous in the western than in the eastern part of the map-area, may be of special interest to prospectors, since a variety of useful minerals, notably phlogopite, are found in some of them.

Paragneiss

Paragneisses are abundantly developed in the Grenville series in all parts of the map-area. The most common type (which is so widespread in the Laurentians that it is unnecessary to describe it here) is a garnet-sillimanite gneiss. Rarer are a paragneiss very rich in mica or amphibolite, and a gneiss which contains an abundance of calcic silicates derived from calcareous rocks and which is usually found in the principal belts of crystalline limestone. This last type, which is generally very much crumpled, outcrops abundantly around Thirty-one-Mile lake and along the shores of Big Cerf lake.

Migmatites

Highly feldspathic and granitized gneisses which differ greatly in appearance from the much more common garnet-sillimanite gneisses have a fairly wide distribution in the area. The two types commonly outcrop in close proximity and there is really no clear-cut boundary between them. These granitized gneisses may be designated 'injection gneisses' or, as in this report, by the term 'migmatites'.

The significant difference between the garnet gneisses and the migmatites is in the degree of metamorphism. The former pass gradually into the latter in such a fashion that it is often almost impossible to make a separation between them, at least at the scale of the accompanying map. -Intrusions, which, 'in general, did not ascend sufficiently high to outcrop at the present surface, caused the granitization of the gneisses, and this in an apparently hap- hazard fashion, here and there in zones or patches of very unequal size, some large, others of very limited extent as witnessed by the nearby presence of paragneisses that have remained almost unchanged.

In their numerous outcrops throughout the area, the migmatites show considerable diversity in appearance. In many of - 14 - them, dark micaceous or sometimes amphibole-rich layers alternate with pale, often pink, layers of feldspar, and the rock has a sharply banded texture. In some, this ribbon banding is almost perfectly regular even over large areas, as though the rock had undergone simple recrystallization without being subjected to tangential pressure. Elsewhere, on the other hand, the bands in the migmatites are extremely drag-folded and complexly crumpled.

In many occurrences, the migmatite is cut by large numbers of veinlets of aplitic or pegmatitic material. Some of these are more or less parallel to the banding; others cut,the rock in all directions. The rock commonly contains some garnet, but only in small amount and in grains of mailer size than those in the gneisses from which the migmatites were derived.

The markedly layered migmatites are generally easily identifiable, but others have been so intensely granitized that, in small areas of outcrop, it is easy to mistake them for intrusive granites. In large areas of exposure, however, this- confusion may usually be avoided. This is the case, for example, with a large body of migmatite that extends west of Big Cerf lake in ranges VII and VIII of Dudley township. Around the borders of the mass, the garnet gneiss from which the migmatite has been derived has remained but little changed, but, in the central portion, it is greatly altered and conveys the impression that one is dealing with a granitic intrusion. However, the presence of fairly numerous bands of crystalline limestone shows that the rock as a whole must be migmatite.

The migmatites are, in many cases, very heterogeneous but they do not necessarily display ribbon banding. In a single outcrop, there is apt to be abrupt variation in both mineral composition and grain size. This is particularly true of the large body of these rocks exposed between ranges V and XI of Robertson township, in the northeastern part of the map-area, and in lesser degree of the migmatites that are found farther south, in Bouthillier, Kensington, and Wabassee townships.

Aplitic facies are common in the migmatites in Robertson township. These are light coloured, greyish or pink rocks, of both fine and coarse grain, and where there are alternations of these tex- tures the rock has a sort of ribbon banding. The usual essential minerals are quartz and orthoclase, the latter intergrown with albite. Biotite or hornblende are rare or lacking. Small amounts of apatite, magnetite, and garnet are almost always present, and, rarely, tourmaline. The quartz, which is occasionally bluish, shows undulatory extinction in thin section, as also does the orthoclase, and quite commonly the rock shows clear evidence of crushing. - 15 - Some of these aplitic rocks are massive, others are gneissic. It is exceptional for them to be uniform in texture and composition over large exposures.

The fact that the aplites are so frequently associated with amphibolites has led the writer to consider the possibility that they are not of intrusive origin but have been derived from the migmatites. Supporting this view is the common occurrence within the aplite of intercalations of amphibolite of very variable size and shape. This is the case in Robertson township and elsewhere, as for example in range II of Dudley. In the aplite in the northern part of ranges VIII and IX of Bouthillier, certain of these zones of amphibolite are several tens of feet thick. In some of these occurrences, it might be thought that the dark coloured rock - composed chiefly of hornblende, with accessory plagioclase feldspar, biotite, garnet, and hypersthene - is a huge inclusion of foreign material; but the fact that in many instances, over considerable widths, the amphibolite occurs in bands alternating regularly with the aplite shows clearly that we are dealing here with a hybrid rock.

There are many occurrences of these banded migmatites, formed of alternating layers of aplite and amphibolite that are strictly parallel but of various thicknesses (from one to several inches and even thicker). A good example may be seen on the eastern shore of Thompson lake near the mouth of Pearson creek, on lot 8, range IX of Robertson township.

The migmatites have a considerably greater development in the map-area than the gneisses at whose expense they have been formed. Moreover, the principal bodies of migmatite are quite often surrounded by an aureole of less granitized and easily reccignizable paragneiss. Thus, in several localities, it is possible to trace clearly the gradual transition from gneiss to migmatite, as on the left bank of the Lièvre in range I of Dudley township.

Because of their superior hardness and resistance to erosion as compared with the gneisses, the migmatites are found underlying the more elevated parts of the area and they form steep hills which, as a group, are the most prominent of the region. Thus the widest belt of migmatites in the area corresponds closely to its most hilly part, that which forms the height-of-land between the drainage basins of Gatineau and Lièvre rivers. This belt extends from north to south across the area, varying from three to seven miles in width. In its northern part, from west of Quinn lake to lake des Iles, there are some gaps, but southward from there it passes east of Achigan lake, completely surrounds Kensington lake, and continues between Thirty- - 16 - one Mile lake and Lièvre River valley. Throughout most of this extent the migmatites are cut by a multiplicity of small injections of aplitic or pegmatitic pink granite which are too widely spaced and of too small size to be shown on the map.

INTRUSIVES OF VARIOUS TYPES

The rocks of the Grenville series have been intruded by igneous bodies which range in composition from acidic to basic. As these intrusive rocks are seldom found cutting one another, their exact age relationships remain in doubt. The order in which they are here described thus has no exact time significance but is that which seems most logical to the writer.

Granitic Intrusives

Bodies of granite are numerous, but most are of small size and for this reason many of them cannot be shown on the accompanying map. The largest bodies mapped, such as that in ranges V, VI, and VII of Aumond township, and the one astride ranges VI and VII of Bouthillier, are not more than a mile wide by two or three miles long. It should be mentioned, also, that the granitic area in Aumond includes bands of gneiss and migmatite that could not be mapped separately. Many of the granitic intrusions, especially those in the limestones, are mere 'knobs' a few hundreds of feet or less in diameter. In these, as a rule, the rock is uniform in character.

Before giving a summary description of the principal types of granite, an observation concerning the genesis of some of them should be made. The margins of some of the bodies of granite are so vague and indefinite that it is very difficult to determine their location, even approximately. Such is the case with several of the bodies that lie within the migmatites. The granites in question, of diverse composition and containing many inclusions, may not, be true intrusions but, instead, may be old gneisses that have been completely granitized. In other words, they may be 'anatectic' granites, the ultimate in the development of migmatites. The practical importance of making such a distinction rests chiefly on the fact that only fresh magmatic material, that is to say material com- ing from depth in truly intrusive fashion, seems able to serve as the transporting medium for certain heavy metals and thus to be significant from the metallogenetic viewpoint. Studies on the ground lead the writer to believe that the more heterogeneous of the granites shown on the map are, in reality, anatectic rather than intrusive granites. This seems to be applicable to certain outcrops in ranges III to VII of Aumond township, ranges XIII and XIV of Robertson, and Plate 1

Thirty-one Mile lake, viewed from the west. The heights overlooking the east shore in the background are in Wabassee township. Roddick lake, Cameron township. "Montagne de Fer" •(Iron Mountain) on the left. Plate Ili

A - Gatineau river, looking upstream from Corbeau rapids (Kensington) township). The escarpment of crystalline limestone is cut by diorite.

B - Limestone bluffs along the left side of Gatineau river (lot 60, range Ill, Cameron township). Plate IV

A - Interbanded limestone and pyroxenite. On the shore of an island in Thirty-one Mile lake (Wabassee township) .

B - Solution effects in limestone. West shore of Thirty-one Mile lake. Plate V

A - Banded gneisses (migmatites) along the west shore of Thirty- one Mile lake (range Vil, Ca- meron township).

B - Quartzite beds at the outlet of Leveillé lake (range VI, Cameron township). Plate VI

A - Garnetiferous paragneiss, east bank of Lièvre river (lot 12, range I, Dudley township) .

B - Banded paragneiss, Bouthillier township. Plate VII

A - Banded garnetiferous paragneiss (lot 18, range V, Dudley township).

B - Small fault in Grenville paragneiss (lot 44, range VII, Bouthillier township). Plate VIII

A - Pyroxenite inclusions in Grenville limestone (lot 11, range V, Dudley township).

B - Folding and injection of granite in paragneiss, (lot 16, range 1V, Dudley township). - 17 - ranges VI and VII of Bouthillier, as well as in range VI of Kensing- • ton. It is considered that these possibilities concerning the genesis of some of the granitic masses should be mentioned.

Among the granitic bodies mapped are some which are so similar in appearance and mineral composition that it is obvious that they are genetically related. Between others, however, the differen- ces are sufficiently marked to create a doubt concerning their belong- ing to a single intrusive phase.

Gneissic biotite granites of a pink, pinkish-grey, or pale grey colour are the most common, and some varieties of these which are low in mica grade into aplites. The predominant feldspar is commonly microcline. This rock type is very abundant in the north- western part of the area, between Murray and Travers lakes.

In Egan township, south of Bois Franc village, several granitic bodies intrude a belt of gneiss Ind quartzite. The rock is pink but, unlike that described above, it is poor in biotite. It is often aplitic and occasionally is slightly pegmatitic. This granite resembles in some respects the numerous small intrusions occurring on both sides of the Gatineau within a radius of four to six miles of Maniwaki. In these, the rock is pale pink or rarely pale grey and its grain size varies even in a single outcrop, grading in some places to a pegmatite with finely graphic texture. It may be gneissic, but the banding is poorly developed because of the paucity of strongly-coloured constituents. Where present, black mica is commonly concentrated in streaks along joint planes. Locally, quartz may be in very small amount and the rock then is composed almost exclu- sively of feldspar. A peculiarity of this granite is that it contains occasional specks of purple fluorite and crystalline aggregates of black tourmaline. This granite, typical of the Maniwaki district, is uniform in composition in some localities but in others it contains numerous inclusions of Grenville rocks and also, commonly, is travers- ed by lenticular veins of white quartz.

Most of these bodies of pink granite have indefinite and extremely irregular boundaries except where, in some localities, they form elonoeted hills.

The only outcrop of granite of the same type as that found in the Maniwaki district that was seen in the eastern part of the map-area is a little south of David lake, in range IIIN of Wabassee township.

A reddish gneissic granite different from those described above, uniform in composition and completely surrounded by migmatites, - 18 - outcrops in escarpments in the hilly country in range IIW of Wabassee township, one mile north of Babiche lake. The abundant quartz in this rock has undulatory extinction. The chief feldspar is orthoclase and it is accompanied by partly altered albite and oligoclase. The ferromagnesian mineral is hornblende, partly altered to epidote and chlorite.

In the limestone belts throughout the map-area are many small irregular masses of a coarse grained, or pegmatitic, whitish granite low in mica. They are especially well exposed around most of the lakes that have limestone shores. The presence of so many bodies of granite in the limestone and of many crumpled inclusions of limestone in the granite bears witness to the intensity of the deformation of the Grenville rocks. To the east of Kensington lake, in range XIII of Bouthillier township, some of these bodies of pegmatitic granite are of relatively large size, forming scarps that stand impressively above the lake.

Very coarse grained. granites, without gneissic structure and locally poor in quartz but higher in biotite than those last described, outcrop in the neighbourhood of Kensington lake, notably in the hilly section of range XIII of Bouthillier township, between the two southern arms of the lake, and again farther to the north, on lots 8 to 11 of the same range. The granite here contains numerous, large inclusions of Grenville rocks.

A gneissic granite fairly high in biotite and with a more or less strongly developed porphyritic texture outcrops over rather wide areas in several places. Two of these are in Aumond township between lots 15 and 17 of ranges A and B and on lots 25 and 26 of range I. The rock contains rather large crystals of mauve microcline. A similar porphyritic granite, with some pyroxene and sphene and grains of bluish opalescent quartz, occurs in a few places in a belt of hornblende gneiss near the south shore of Travers lake, in ranges XII and XIII of Robertson township.

A body of coarse grained biotite granite is exposed in ranges VII and VIII of Dudley township and extends from Libvre river to: beyond Mallonne lake. This is the largest such intrusion in the eastern part of the map-area. Southeast of the main body, near Lac du Cerf village, rocks of the Grenville series are injected by small bodies of this granite.

Another variety of granite to be mentioned is an olive- green rock that occurs as several small masses intruding the gabbros of range XI of Robertson township. A body of this type also occurs near the northern boundary of the map-area. The rock is composed of - 19 - bluish quartz, orthoclase, micropegmatite, pyroxene, and amphibole. It is probable that this granite is genetically related to the gabbro.

Microscopic examination of these several types of granite shows that, in general, they have been subjected to pressure, as is evidenced by the undulatory extinction in the constituent minerals. Also noteworthy is the fact that pleochroic haloes are usually absent in the biotite.

In many places, pegmatite dykes,, composed chiefly of microcline with more or less quartz and little biotite, accompany the granitic intrusives. In general, they are irregular in form and of very limited extent. A noteworthy example is a dyke, trending N.E.- S.W., that cuts the garnet gneiss in the town of Maniwaki. It is composed mainly of feldspar and outcrops on the north slope of the hill on which the church is built. Another of these dykes worthy of note outcrops alongside the road from Maniwaki to Bois Franc lake, in the eastern part of lot 20, range III of Kensington township. It cuts, and contains inclusions of, limestone.

As will appear from the foregoing descriptions, the granites of the area are of several types and, in the absence of cross-cutting, their relationship to one another remains in doubt. On lithological grounds, however, some of them may be tentatively correlated with similar but much larger granitic intrusions that occur in the Laurentians farther east.

The pink granites low in dark minerals that are found in Egan township and in the vicinity of Maniwaki and of David lake resemble the Trembling Mountain granite, which is believed to be the oldest intrusive to have cut the Grenville series. It is probable that, of the other granites found in the map-area, some belong to the. Morin series. This would apply in.particular to the pyroxene granites that at several places cut the gabbros of Robertson township. Also, the porphyritic granites of Aumond and Robertson townships may be equivalent to the Pine Hill granite of the Morin series.

Kensington Svenite

A large body of syenite underlies the north-central portion of Kensington township; it is the largest body of intrusive rock in the map-area. Its boundaries are well defined on the north and west, where contacts of the syenite with Grenville rocks can be closely followed and are even exposed in places. To trace the southern border of the massif is much more difficult, especially along the stretch of country from the large swampy depression in range V of Kensington, past the north shore of Laframboise lake, to the area -20- lying northwest of Achigan lake. Here, outcrops are rather sparse and, besides, the syenite contains many large inclusions of amphibolite and micaceous pyroxenite. In most cases it is a matter of doubt as to whether these 'inclusions' are much altered lenses of Grenville rock, or ultrabasic intrusives, or an unusual, very basic facies of the syenite itself. In this connection it should be mentioned that, in this southern part of the stock, much of the syenite has an ab- normally high content of biotite and amphibole. For the present, therefore, this southern border of the massif must be considered as a rather complex zone.

The syenite body measures about seven miles from east to west and a little more than three miles in its maximûm north-south dimension. The rock is coarse grained, unfoliated, and is nowhere gneissic. Its macroscopic appearance is variable. In the western part of the stock, the rock is usually pink and low in dark coloured minerals; in the central part it is generally grey. In places, the development of the feldspar crystals is such as to give the rock a slightly porphyritic aspect and it then resembles the quartz porphyry of the Sicotte area, suggesting that, like the latter, it may be the equivalent of the Pine Hill syenite (Morin series).

The Kensington syenite contains both microcline and orthoclase, either of which may predominate. With these is a lesser amount of oligoclase and also of albite, the latter intergrown with the po- tash feldspar. Biotite is the chief ferromagnesian constituent, but hornblende also is present in some facies of the rock. Sphene is a common accessory mineral, occurring as small aggregateb of crystals included in the feldspar and in the hornblende when this is present. Usually the rock contains quartz in such amount that it is visible to the naked eye.

Large inclusions of a fine grained, grey, gneissic rock are relatively abundant in some parts of the massif. Such is the case at the top of the mountain on which is situated the forestry tower, in lot 30, range III of Kensington, and also near the northwest side of the swampy depression in ranges IV and V of the same township.

Locally, the syenite is cut by dykes of pink granitic and syenitic aplite. These are from a few inches to a few feet wide. It is intruded also by a few small pegmatite dykes, notably in lots 45 and 46 of range IV, Kensington township. Elsewhere, as in lot 32 of range III, the syenite contains a few narrow, poorly defined zones of tourmaline-bearing pegmatite that seem to be segregations rather than dykes.

A second, isolated body of syenite outcrops a short distance southwest of Kensington lake. The rock is pink, coarse grained, - 21 - devoid of inclusions, and is low in dark coloured minerals. A similar syenite intrudes the gneisses a little southeast of Travers lake, in lot 10, range XI of Robertson township.

Other Svenite. Monzonite. and Diorite Intrusions

Grey, massive, fine grained rocks that contain abundant mica and have the composition of syenite, quartz diorite, or monzonite are of common occurrence in the western part of Kensington township and are found elsewhere, principally in Aumond township and on the Indian reservation at Maniwaki between Brady lake and Gatineau river, at the head of Tête-des-Six rapids.

These rocks are generally found in areas of limestone and amphibolite. They are well exposed in a series of large outcrops along a five-mile, southwest-trending zone from lot 27, range V, to lot 6, range II, of Kensington township. In at least two places, the micaceous syenites and diorites seem to intrude the syenite of the Kensington massif. As the latter is not cut by any other intrusive rock, it can be deduced that the rocks in question are amongst the youngest in the region. They themselves have not been intruded by any younger rocks unless by the light-coloured pegmatitic granite, which more probably is a differentiate of the same magma.

The rock outcropping in several places in range I of Kensington township, between lots 29 and 33, and which Wilson has described as hornblende kersantite, is not essentially different from the micaceous monzonites and syenites just discussed. It is greyish and is composed of equal parts of feldspar and ferromagnesian minerals (biotite and amphibole), with fairly abundant sphene. The rock is fractured, and has gradational contacts with the limestones and quartzites it intrudes. .One of its characteristics is that it is criss-crossed by many stringers of pink aplite. These are about an inch thick on the average, are very crumpled and branching, and, because of their greater hardness, stand in relief on the outcrop. They appear to be more acidic differentiates that formed within the magma itself as it consolidated.

Similar differentiation features characterize other occurrences of these rocks, notably in exposures in the.eastern part of lots 15 to 18, range III of Kensington township, where the rock varies in composition between a syenite and a monzonite and exhibits pale coloured zones that are less micaceous than the darker portions of the rock. - 22 - Gabbro

Bodies of gabbro are relatively numerous in the eastern part of the area, but in the western part only a single outcrop was seen. This had already been mapped by Wilson, who reported it as being in lot 14+ of ranges "East and West of the Maniwaki road", in the Indian reservation. The outcrop is small and not well exposed, and was found by the writer only after much search'. As pointed out by Wilson, it appears to be a fragment of a greatly deformed dyke lying in the midst of the crystalline limestones. The rock is light coloured, pyritiferous, and low in pyroxene.

Gabbro, altered to pyroxene orthogneiss, outcrops a little south of, the outlet of Travers lake, in lot 16, range XII of Robertson township, in a complex zone where amphibolitic gneisses and porphyritic granite are the predominant rocks. The relationship of the gabbro to the adjacent rocks could not be determined. Under the microscope,. the rock is seen to be composed of augite, hypersthene, hornblende, biotite, and very basic plagioclase, the grains of which are severely crushed. There is, besides, a fair amount of quartz; this is astonishing in so basic a rock, but it is doubtless of secondary origin.

Gabbro differing from that just described, but very similar to that occurring in the Nominingue and Sicotte areas, forms several massifs in the eastern part of the map-area. The rock is massive and devoid of inclusions. The grain size is variable and in some outcrops so coarse that the rock is almost pegmatitic. Being resistant to erosion, these gabbro massifs generally form rugged hills and escarpments. Possibly stemming from a single mass at depth, most of them are found in the south-central part of Bouthil- lier township. They form an almost continuous belt extending along the right bank of Lièvre river almost to Perron lake, a distance of nearly four miles across ranges VI to IX of the township. A short distance away from these main bodies are others, as for example around Bouleaux lake (range VI) and south of Pearson lake (ranges X and XI).

Smaller bodies of gabbro are found in ranges X and XI of Robertson township and at several other places in the map-area.

Microscopic examination reveals that, in many of these bodies, the rock has been severely crushed. Most of the thin sections examined contain hypersthene, biotite, and hornblende in addition to the essential augite and plagioclase. A small amount of quartz is often present. The rocks may therefore be classified in a general way as quartzose micaceous hypersthene-bearing gabbros. - 23 - Near certain of the gabbro bodies, the Grenville rocks are cut by dykes of microgabbro. This is a fine grained, grey rock. The dykes are of various widths but are usually several feet wide. They are especially numerous in ranges VI and VII of Bouthillier township, particularly south of Paquet brook. Here, they strike in any and every direction. They are, without a doubt, related to the bodies of gabbro occurring in the vicinity.

Basic Dykes

Grouped under this category, and separately from the ones just described, are some dark, basic dykes which cannot be correlated with any of the intrusive rocks discussed above. They are of no practical significance and are of such small dimensions that but few of them can be shown on the accompanying map. The position arbitrari- ly assigned to them in the table of formations and in the legend of the map maygive the impression that they are relatively young and possibly contemporaneous with the diabases known farther south, in Papineau and Argenteuil counties. In fact, however, these dykes, or at leastsome of them, seem to be very old as judged by the intense deformation they have undergone. It is of interest to note that almost all of those observed occur in the limestones.

These small basic dykes are, for the most • part, tightly folded, stretched out, and broken, and ordinarily they occur only as segments measuring a few tens of feet, so that it is difficult to determine their strike. For some, the general trend is northeast- southwest, for others, northwest-southeast.

For the most part, these dykes are found in outcrops of limestone along the shores of lakes and streams. Several were seen around Kensington lake. Some examples are: a basaltic dyke in lot 37, range XI of Kensington township; a dyke of microgabbro in lot 10, range XIII of-Bouthillier; and, not far from this, in lot 16 of the same range, a dyke of microdiorite cutting a vein of pegmatitic granite. The limestone near the east shore of lake des Iles (lot 3, range III, Robertson township) is cut by -a microgabbro dyke that is only five inches thick. A much crumpled dyke of mica-amphibole microsyenite from one to three feet thick occurs in the limestones on the north shore of Achigan lake. -

There are also several small dykes of basalt between Noire and Davis bays at the north end of Thirty-one Mile lake; along the north shore of Michel lake; and in the limestone cliffs that slope sheer into the Gatineau opposite Boom island. - 24 - Finally, there is a mica-amphibole rock in the eastern part of lot 16, range III of Kensington township. The outcrop measures a few tens of feet.in diameter and seems to be part of a pipe- like mass rather than of a dyke.

PLEISTOCENE AND RECENT

The unconsolidated superficial deposits of glacial, fluviatile, and lacustrine origin cover a large area in the low-lying terrain in the eastern and western parts of the map-area.

In most parts of the map-area there is evidence of one kind or another of the passage of the Pleistocene glaciers. Striae were seen on rock surfaces in numerous places and with few exceptions they indicate that the direction of ice movement was S.10°E. The deviations from this were all between S.5°W. and S.10°E: Among the striking features of the topography that owe their origin to glaciation are the asymmetric profiles of many of the hills, as for example Lac des Iles mountain (range V, Bouthillier township) and Tower mountain (range II, Dudley), whose southern slopes are noticeably more abrupt than those to the north.

Morainic accumulations of rounded boulders are widespread in those parts of the area where there are gentle slopes, but such accumulations are buried beneath younger deposits in the lower ground. Moraines are particularly well developed on the hills on either side of the Gatineau valley, and on each side of lake des Iles. There is an extensive, well-preserved lateral moraine just east of the village of Lac des Iles.

Several groups of eskers whose general trend is N.N.E. were observed. One group extends through the low-lying area south of the big bend of Joseph river (ranges II and III, Kensington). Another, even more clearly defined, group trends across the sandy plain north of Travers lake (range XII, Robertson). Still farther to the east, other eskers may be seen in range X of Robertson township and range IX of Bouthillier.

The distribution of the morainal deposits is so irregular that they have not been shown on the accompanying map. However, the post-glacial fluviatile and lacustrine deposits have been distinguish- ed. These consist of grey clays, commonly varved; yellow (ferrugin- ous) quartzose sands; gravels; and boulder deposits. Sandy deposits with some admixture of gravel are the most widespread. They are found over a large area in the flat or gently rolling country southeast of lake des Iles, and are especially extensive in the central part of Bouthillier township. Similar sand deposits cover large - 25 - stretches in and around the town of Maniwaki and in the southwest corner of the map-area.

Several of the alluvial plains of the area - and particularly those in the western section - lie at altitudes between 550 feet and 650 feet, that is to say at an elevation below, or about the same as, that of the highest level believed to have been reached by the Champlain sea. Keele and Wilson are of the opinion that, during this great transgression, the waters of this sea advanced almost to Maniwaki by way of the channel formed by the valley of the Gatineau. Such may have been the case, but, up to the time of writing, no marine fossil has been found in the alluvial deposits of the map-area and their marine origin therefore remains to be proved. It seems more logical to postulate that these beds accumulated at the bottom of an estuary which was occupied by the fresh waters that must have flowed into it from all the adjacent valleys where, no doubt, tongues of the glacier yet remained. The very large volume of such melt waters must, assuredly, have pushed back the marine waters which were tending to flow into the Laurentian terrain by narrow channels such as the Gati- neau and Lièvre River valleys.

STRUCTURE

The main topographic trend lines of the area have a general north-northeast direction. This is true of the most prominent ranges of hills, and especially of those in the central portion of the area, which form the height-of-land between the drainage basins of Gatineau and Lièvre rivers. The valley of the latter also has this general trend and that of the Gatineau departs from it but little. It appears again in the arrangement, and in the long dimension, of several of the main lake basins (Quinn lake, Thirty-one Mile lake, La Vieille-Lochiel lake, the chain of lakes along Pearson creek, Little Cerf lake, etc.).

In the western part of the area, where the Grenville beds are least disturbed and show their original stratification, their strike is somewhere between north-northeast and east-northeast and the most common dips are eastward. This is especially the case in belts of garnet gneiss and banded migmatite. It should be noted, too, that the strike of the gneiss and the topographic trend are, locally, perfectly concordant. Thus, in places along the western .shore of Thirty-one Mile lake, there is strict parallelism between the direction of the shoreline, the long axis of the neighbouring islands, and the strike of layering of the gneiss. Similar parallelism was observed at numerous places and in particular around lake des Iles, where the trend of much of the shoreline and of many of the islands is the same as the strike of schistosity in the gneisses. 26 The same is true of many smaller relief features whose orientation is a consequence of the structural trend of their component rocks.

The regular attitude of the gneisses, with a predominant east-northeast strike, does not obtain everywhere however, and regularity in the'strike of the beds of thé Grenville series is often every localized feature. In the eastern part of the area, the lack of regularity in strike and dip of the formations is particularly notice- able.

The Grenville series has experienced several`orôgenies of such magnitude, and its metamorphism is so intense, that it is scarcely to be hoped that its complex structure can be completely deciphered. Many of the very numerous determinations of strike and dip made by the writer give no really positive indications of the general structuré. The most that can be inferred is that the area here dealt with possibly lies on the eastern limb of a very large anticlinal -fold whose axis trends approximately east-northeast.

As has been mentioned, the boundaries of most of the granitic and other intrusive bodies are vague and indefinite. The Kensing- ton syenite and the gabbro bodies are about the only ones that have fairly sharply defined boundaries. Their shape and orientation, however, scarcely accord with the general structure outlined above. Only the large belts of migmatites seem to be in harmony with it.

ECONOMIC GEOLOGY

There has been no systematic prospecting in the map-area, but in a number of places more or less chance discoveries have been made of -interesting occurrences of a variety of 'industrial' minerals, notably phlogopite (mica), and also of metallic mineralization. Some of these have been investigated by a limited amount of surface work and test pitting.

The widespread Pleistocene sand and gravel deposits afford material for use locally in road construction and as concrete aggregate, and in past years limestone was quarried in several places for production of lime.

Zinc

•A considerable amount of development work was carried out some twenty-five years ago on a zone of zinc mineralization in lots 41 and 42 of range II and lot 42 of range III, Souchette township. This occurrence was first mentioned in a report by Hoffman published - 27 - by the Geological Survey of Canada in 1899, and on several occasions in subsequent years it.attracted the attention of prospectors. The last effort to develop the deposit was made, it appears, in 1927, when a total of 1,900 feet of trenching and 1,426 feet of diamond drilling was carried out, the deepest drill hole going to 429 feet'. The trenches are now for the most part fallen in, water filled, or partially masked by vegetation. They show a number of sulphide-bearing lenses, all of small size, that are rather widely scattered over a distance of about a mile in an east-west direction. These lenses occur in bodies of pyroxenite that are cut, here and there, by pegmatite dykes and associated with which there are metamorphosed limestones and gneisses of the Grenville series. Apart from the pegmatite dykes mentioned, no granitic or other intrusion is to be seen in the immediate vicinity. The sulphide minerals present in the lenses are sphalerite, pyrrhotite, and, more rarely, pyrite.

Because of the age of the workings and the obscured condi- tion of the mineralized parts of the exposures, it is difficult to assess the actual worth of the occurrence. All the evidence indicates that sphalerite was found at only a few places and not in all the sulphide"lenses that occur in the workings. The writer_ observed significant amounts of sphalerite in only three places. Everywhere else, the accessible exposures and the débris from the trenches show only pyrrhotite and pyrite.: These minerals are commonly massive and in some of the excavations they are present in relatively":large -.amount.

Galena is said to have been found in some places with the y sphalerite, but the writer was unable to find any trace of this mineral.

Selected samples of mineralized material taken from three places in the mineralized zone where sphalerite is present were analyz- ed in the laboratories of the Quebec Department of Mines with the re- sults tabulated below.

Gold . Silver Pb Zn Cu Fe Insol. oz./ton oz./ton.. % % % . % : % Lot 41, range'II Trace 0.170 Nil 14.31 0.03 9.82 59.82 Lot 42, range II Trace 0.060 Nil 19.70 0.03 17.78 32.44 Lot 42, range II 0.006 0.234 Nil 10.13 0.11 37.03 9.48

'Burton, Fred R., Notes on the Souchette Township Map in "Geological Traverses in Maskinonge, St. Maurice, PortneUf, Quebec, and Montmo- rency counties; Que. Bur. Mines, Ann. Rept., 1928, pp.10 and 11. - 28 - Magnetite

Some poor showings of magnetite, evidently of no economic interest, were found in certain layers of quartzite interstratified with migmatites and paragneisses, notably in lot 43, range XI of Bou- thillier township, and lot 26, range II North of Wabassee.

Molvbdenite

Molybdenite has been reported at two places. Wilson mentioned its occurrence in lot 4, range I of Egan township, where four trenches were opened in 1919. One of the trenches exposed a lens. of pyroxenite,ten feet wide, through which small flakes of molybdenite are sparsely disseminated.

The other occurrence was found by Pierre Morin about twenty years ago. It is in lots 45 and 46 of range IV, Kensington township, on the northwest side of a hill a few hundred feet east of the road leading from Maniwaki to Ferme Joseph. Development work, consisting of a fairly wide and deep excavation, was undertaken at this locality in 1939. In the autumn of 1943 further work was done under the direction of the Moldor Exploration Syndicate, of Toronto. When work was suspended in November of that year, some stripping and a few shallow trenches along a length of 250 feet had been completed. The mineralization is related to a branching pegmatite dyke that strikes N.35°E. The main dyke has a maximum width of 35 feet. It is composed chiefly of pink feldspar and has cavities lined with well formed crystals of microcline. Quartz is absent but there is a fair amount of biotite in places. The dyke cuts the Kensington syenite and contains inclusions of bands of grey, highly feldspathic gneiss and of an unusual metamorphic rock composed of magnetite and biotite with minor calcite and sphene. For the most part, the molybdenite is confined to the pegmatite, in which it occurs either as small, isolated lamellae or as clots and flaky aggregates composed entirely of Molybdenite. In the course of the prospecting operations, flaky crystals of molybdenite as much as ten inches in diameter were recovered. The gneissic and micaceous inclusions in the dyke are also weakly and irregularly •mineralized with molybdenite. The syenite wall-rock is usually barren.

Graphite

Graphite is common as minute flakes disseminated in the crystalline limestones and occasionally also in the 'quartzites and gneisses. Richer showings are known at some localities, but it seems unlikely, despite the good quality of some samples, that they might be of economic importance. In 1942, some work was done on a small show-

ing of this type in the gneisses in lot 51, range VI of Bouthillier township, between the right bank of Lièvre river and the Buckingham- Mont Laurier highway. A pit, 10 ft. by 7 ft. by 4 ft. deep, was opened which revealed a few veins of pure scaly graphite. However, the veins are all less than two inches thick, and apparently they have a length of not more than ten feet.

High quality flake graphite has been reported as occurring opposite Pontmain, in range III of Dudley township, not far from the left bank of Lièvre river. The writer was not able to visit this occurrence and has no precise information concerning it.

In the eastern part of lot 48, range IV of Cameron township, a lens of grey pyroxenite - an inclusion in the limestone - contains numerous veins of graphite. The outcrop is elliptical in form and measures about 70 feet by 50 feet, with the long axis trending N.50°W. The graphite occurs in flaky aggregates, either of graphite alone or of graphite mixed with diopside, which form very irregular veins an inch or a little more in thickness. The veins are highly deformed and criss-cross one another to form a network in the pyroxenite, which, in the intervals, is almost barren.

Muscovite

Muscovite is a main constituent of a large, tourmaline- bearing pegmatite dyke exposed near the north shore of lake des Iles, in lot 25, range IV of Robertson township. The occurrence has been known for more than thirty-five years and was once mined for mica in a small way. The muscovite is in sheets two to four inches in diameter but is commonly much cracked. In or about 1940, interest in this dyke was revived because of its reputed content of beryl. Frag- ments, weighing a pound or more, of large crystals of stony beryl of a greenish-white colour were shown the writer in Mont Laurier and were. said to have been taken from this pegmatite dyke. However, close examination by the writer failed to reveal the presence of beryl either in place in the dyke or in the débris from the workings.

In l943,•very clear and flawless muscovite, in plates up to five inches in diameter, was found by A. Guilbaud in a quartz peg- matité dyke in lot 53, range II of Kensington township,a quarter of a mile west of the Maniwaki-Mont Laurier road. The dyke, which is lenticular in form with strike N.60°E., intrudes garnet gneiss. Strip- ping operations carried out in the autumn of 1943 uncovered the dyke over an area 10 feet by 6 feet and showed that it pinched out each way along the strike. The occurrence is thus of very minor importance, particularly, as no other similar dykes were found in the vicinity.

Ministère des Richesses naturelles du Québec

SERVICE DOCUMENTATION TECt r. IQUE - - Phlogopite

Phlogopite, closely associated with lenses of pyroxenite that are included in the limestone, gneiss, and quartzite of the Gren- ville series, is abundant in the western part of the area, but much rarer in the eastern part. In former years there was a small production of phlogopite from some of these deposits, which are said to have furnished good sized sheets of excellent quality. In all of them, however, there was a considerable proportion of unmarketable, waste mica. In most of the occurrences examined by the writer, the phlogopite forms lenses and irregular veins in the pyroxenite bodies and often occurs as complex crystal aggregates from which it is difficult to split large sheets that are free of imperfections. The largest crystals seen were from four to eight inches in diameter. Zany of them, however, were bent, twisted, crumpled, full of inclusions, rusty, and cracked along planes perpendicular to the cleavage. These imperfections limit considerably the size of the usable portions of the crystals.

Locations of the principal known deposits of phlogopite are given in the following tabulation.

Township Range Lot Aumond B 7, 13, 14, 20 " I 15 " III 5,6 Bouchette I 38,39 Bouthillier VII 55 Cameron III 50,51 VII 47 Egan B 46 " I . 15 If II 28 Kensington I . 44,45 !' V 7 Maniwaki E. Maniwaki 20,21 Road " W. Maniwaki Road 15,21 " IV 21. Robertson XIII 9

At various times dating from fifty or more years ago, a certain amount of development work or open-pit mining has been carried on at many of the localities listed above, the last of these operations having been in Cameron township, in 1924. Most of the - 31 - old pits are now flooded. There is no doubt that phlogopite deposits could be found in many other places in the map-area, particularly in the unsettled or little travelled sections.

Chrysotile Asbestos

Chrysotile asbestos, in very thin veins in crystalline limestone, was found in lot 40, range III of Cameron township, near the north shore of Roddick (Round) lake, and in'lot 52, range IV of Ken- sington, a short distance northwest of Joseph (Miller) lake.

Quartz,

In a small area in the middle of lot 7, range B of Aumond township, a short distance north of Ecarté lake, small, perfectly clear quartz crystals have been found lying loose in the surface soil. Mr. Britt, owner of the land in question, has dug several pits in this locality which have shown the presence of p band of massive milky quartz, striking N.45°W. This quartz appears to be of secondary origin and not vein material. The band is several tens of feet wide and of undetermined length. Fissures and cavities in the milky quartz are lined with small crystals of clear quartz (rock crystal), the largest observed being barely one inch in diameter. These are enveloped in a soft, whitish mass of very short fibred tremolite.

Similar bands of massive white quartz, cavities in which are lined with small clear crystals, are found also in the limestones in lot 8, range VII of Bouthillier township, along the road known as "the Valley Range road". The quartz bands parallel the banding of the limestone, which strikes N.15°E.

Garnet

In certain belts of paragneiss, garnet forms up to 50 per cent of the rock. A particularly good example of such a rock may be seen in range VI of Robertson township, in the hills overlooking Tru- del lake from the southeast. However, here as elsewhere, the garnet appears to be too intimately mixed with the other constituent minerals of the gneisses to be easily exploitable. Building Materials

So.far as the writer is aware, there have been no quarries opened in the area for the production of granitic or other rocks for use as building stone. Nevertheless, several of the granites, many of the migmatites, the syenite of Kensington township, and the gabbro intrusions in the vicinity of Wabassee, could all probably furnish some stone of excellent quality for building and other uses.

Pleistocene deposits, chiefly sand and gravel beds, are present almost everywhere in the lower parts of the area, There are, - 32 - as a consequence, numerous sand and gravel pits in or near almost all the settled sections. These have been the source of material for construction and maintenance of roads and for use as concrete aggregate. As the deepest of these pits show, these superficial deposits are at least 50 feet thick in some places.

Deposits pf relatively pure limestone are common and, in past years, the stone has been quarried in several places for production of lime for local needs. None has been made since 1940 at least, but it is stated that the lime produced in the past was, in general, of good quality. For purposes of record, following is a list of places where lime-kilns were in operation:

Townshio Range Lot Aumond III 6 " IV 4 " V 20-27 Bouchette II 27 Cameron II 40 Iv 42-48 It V 56 Dudley VIII 46 Egan C 46 Kensington I 14-17 " III 3-21 IV 14-51

V 48

CONCLUSIONS

From the foregoing summary of occurrences of economic minerals, it will be evident that, of the several Precambrian formations of the map-area, the Grenville series is the one which may eventually be of greatest interest to the prospector. It is possible that certain of the limestones contain brucite, an important deposit of which occurs in Grenville limestone at Wakefield, south of the district described in this report. Brucite, which is the hydroxide of magnesium, Mg(OH)2, is particularly in demand at the time of writing for the production of magnesia, used in the manufacture of certain refractories and also, in some processes, for production of magnesium metal.

Not only the Grenville limestones, but the gneisses also, should be examined with a view to discovering within them zones of metamorphic pyroxenite. This rock is of special interest because most of the metallic and industrial minerals now known to occur - 33 - in the region are associated with it. This is true, as has been shown, of sphalerite, molybdenite, graphite, and - most important because of its abundance - phlogopite.

Pegmatite dykes should also be sought out and carefully examined.

ALPHABETICAL INDEX

Pa e Page Agriculture in area 7 Desert river 4 Albite 20 Dion, Armand Alie, R., sawmill 7 Acknoyvledgment to 2 Amphibole 19,21 Diopside 10 Amphibolite 12,20 Diorite 21 Apatite 12,14 Dubé's sawmill 7 Aplites 15 Dudley reservoir 2 Asbestos 31 Dykes - Aubert de Le Rue, E.- Basalt 23 Ref. to report by 5,8 Basic 23 Augite 22 Microgabbro 23 Microsyenite 23 Bell, R.- Pegmatite 19,20,27,29,33 Ref. to work by 8 Bennett, Foster - Epidote 12,18 Acknowledgment to 2 Eskers 24 Big Burn 7 Biotite .... 12,14,15,20,21,22,28 Feldspar 10,11,15,18,19 Granites 17 Ferme Joseph 6 Bois •Franc 6 Filion's sawmill 7 Souchette 6 Britt, Mr. Gabbro 10,22,26,31 Ref. to work by 31° Galena 27 Brucite 32 Garnet 11,14,15,31 Building materials 31 Gatineau Power Co. 7 Gatineau river .4 Calcite 28 Glaciation 24 Can. International Paper Co. .. 6 Gneisses 9,10,13,18 Cerf creek 4 Grand Brulé 7 Cheval Blanc rapids 7 Grande Marsh 3 Chlorite 18 Granite 10,16,17,18,19,31 Chondrodite 10 Graphite 10,11,28,29 Chrysotile asbestos 31 Gravel 24,26,31 Corbeau Rapids 7 Grenville -34- aga Pa e Limestone 10,32 Moraines 24 Series 9,26,32 Marin,_Pierre -. Guérette, R., sawmill 7 Ref. to work by 28 Morin, Romeo - Hills of area 3 Acknowledgment to 2 Hoffman, G.C. - Moulin de la Grande Pointe 7 Ref. to work by 8,26 Monzonite 21 Hornblende 14,15,18,20,22 Muscovite 29 Kersantite 21 Hurtubise, Jules - Notre-Dame-de-Pontmain 6,7 Acknowledgment to 2 Hydroelectric power 7 Orthoclase 14,18,19,20 Hypersthene 15,22 Paquet creek 4 Inhabitants of area 5 Paragneisses 10,13 Injection gneisses. 13 Pearson creek, 4 Iron Mountain 12 Pegmatite dykes,.. 19,20,27,29,33 Phlogopite, 10,13,26,30 James MacLaren Co. 7 Plagioclase 12,22 Joseph river 4 Plains of area 2 Pleistocene - Keele, J.- Deposits 31 Ref. to work by 8,25 Rocks 9,24 Kersantite 21 Sand 26 Pont de Pierre. 5 Lac-des-Iles 6 Post creek 4 Lac-des-Iles river. 4 Porphyritic granites 19 Lac-du-Cerf 6 Prospecting in area 26 Lachance, Jerome - Pyrite 27 Acknowledgment to 2 Pyritic quartzite 12 Lakes of ,area 4,5 Pyroxene, 19 Lièvre river 4 Orthogneiss. 22 Lime-kilns 32 Pyroxenite .13,28 Limestones 9,10,23,32 Pyrrhotite 27

Magnetite 14,28 Quartz. 10,11,14,19,22 Maniwaki, 6 Quartzite 9,11,12 Mica 17,26,30 Mica-amphibole rock 24 Recent rocks. ' 24 Microcline 17,18,19,20 Rivers .of area 3 Micropegmatite, 19 Rock ,Bridge 5 Migmatites .9,13,14,17,31 Mineralization 28 Ste-Famille-d'Aumond 6 Moldor Exploration Syndicate 28 Ste-Thérèse-de-Gatineau 6 Molybdenite 28 Sand. 24,26,31 Montagne de la Tour 3 Schmid, Hugh S.- - 35- Page Page Ref. to work by 8 Taché, Rev. P.L.- Sink holes 11 Ref. to work by 8 Sphalerite 27 Timber of area 6 Sphene 12,18,20,21,28 Tower mountain 3 Spinel 10 Tourmaline . 1+,20,29 Springs of area 5 Valley Range 3 Strong's mill 6 White Horse rapids 7 Subterranean streams 5 Wilson, M.E.- Sulphide minerals 27 Ref. to work by . 8,21,22,25,28 Syenite 19,20,21,26,31 Zinc 26 J