RASM 1934-D2(A) THE PALAEOZOIC OF THE DESCHAMBAULT REGION, PORTNEUF COUNTY dG , eLGIGGGU~GG~ „if-7' PROVINCE OF QUEBEC, CANADA
BUREAU OF MINES Honourable J. E. PERRAULT, Minister of Mines J. L. BOULANGER, Deputy-Minister A. O. DUFRESNE, Director
ANNUAL REPORT OF THE QUEBEC BUREAU OF MINES FOR THE CALENDAR YEAR 1934
JOHN A. DRESSER, Directing Geologist
PART D
Dartmouth River Map-Area, Gaspé Péninsula, by I. W. Jones 3 The Palaeozoic of the Deschambault Region, Portneuf County, by Abbé J. W. Laverdière. .. 45 Mount Megantic Area, Southeastern Quebec, and its Placer Gold Deposits, by H. W. McGerrigle . 63
QUEBEC PRINTED BY R. PARADIS PRINTER TO HIS MAJESTY THE KING 1935 PROVINCE OF QUEBEC, CANADA
BUREAU OF MINES Honourable J. E. PERRAULT, Minister of Mines J. L. BOULANGER, Deputy-Minister A. O. DUFRESNE, Director
ANNUAL REPORT OF THE QUEBEC BUREAU OF MINES FOR THE CALENDAR YEAR 1934
JOHN A. DRESSER, Directing Geologist
PART D
Dartmouth River Map-Area, Gaspé Péninsula, by I. W. Jones The Palaeozoic of the Deschambault Region, Portneuf County, by Abbé J. W. Laverdière... Mount Megantic Area, Southeastern Quebec, and its Placer Gold Deposits, by H. W. McGerrigle.
QUEBEC PRINTED BY R. PARADIS PRINTER TO HIS MAJESTY THE KING
1935
Part D Palaeozoic of Deschambault Region 45
THE PALEOZOIC OF THE DESCHAMBAULT REGION PORTNEUF COUNTY
by Abbé J. TV. Laverdière
TABLE OF CONTENTS Page INTRODUCTION 46 Location of area and transportation facilities 46 General features of region and map-area 46 Field work and acknowledgments 48 Previous work in the area 48 GEOLOGY 49 Table of formations.. 50 Precambrian 50 Palaeozoic. 51 Trenton limestone 51 1.—Deschambault area... 51 2.—Saint-Marc area. 55 Utica shale 58 STRUCTURE 61 Folding. 61 Faulting 62
MAP AND ILLUSTRATIONS
Figure 1.—Geological map of Deschambault region .. 52 Figure 2.—Sketch-map showing Belisle brook where it crosses the fault 58 Figure 3.—Plan and section of formations on lot 207, parish of Portneuf 60 46 Quebec Bureau of Mines 1934
THE PALÆOZOIC OF THE DESCHAMBAULT REGION
PORTNEUF COUNTY *
by Abbé J. W. Laverdière
INTRODUCTION
LOCATION OF AREA AND TRANSPORTATION FACILITIES
The area dealt with in the following pages is in Portneuf county, on the north shore of the St. Lawrence river, some forty miles west of the city of Quebec. Its northeast and southwest boundaries are two lines at right angles to the river and eight miles apart, the one passing through the railway station at Portneuf, the other a mile to the west of the village of La Chevrotière. The Sainte-Anne river, some eight miles inland from the St. Lawrence and here nearly paral- leling it, forms the northwestern boundary. Deschambault, forty-two miles west of the city of Quebec, is the principal village in the district, which is served by three railway lines: the Canadian National (formerly Great Northern), which follows the St. Lawrence from Quebec as far as Deschambault and there turns to the northwest; the Canadian Pacific, parallel to and north of the last, at about a mile and a half from the river; and the Canadian National (former Transcontinental), a little to the north of the other two lines. Four roads, branching at right angles from that which follows the river, lead inland and cross the usual "concession" roads.
GENERAL FEATURES OF REGION AND MAP-AREA
From a short distance below the city of Quebec southward to Montreal and beyond, the north shore of the St. Lawrence is under- lain continuously by Palaeozoic strata, which form a band of varying width, bounded on the inland side by the Precambrian rocks of the * Translated from the French. Part D Palæozoic of Deschambault Region 47
Canadian Shield. Over much of its length this band has a width of ten to twelve miles, but in a general way it broadens towards the southwest and in the vicinity of Montreal the width is about thirty miles. At two points in Portneuf county, tongues extend south- ward from the Shield nearly to the St. Lawrence, thus greatly re- stricting the width of the Palæozoic band which, near the villages of Neuville and Deschambault, has a width of only one or two miles.
From the city of Quebec to Neuville, the sedimentary formations are chiefly shaly in character, but to the west of the latter village the underlying limestone appears at the surface, to form a narrow belt between the shale and the Precambrian granite. This continues to near the village of Deschambault, but immediately west of the tongue of Precambrian that here projects southward, there is a deep embay- ment in the Shield, and the belt of limestone suddenly widens. Also, near this locality, in the vicinity of Grondines, there is a break in the continuity of the overlying shale beds along the river shore, and, for a distance of about three miles, the whole width of the Palœozoie band, here about twelve miles, from the Shield to the St. Lawrence, consists of limestone.
The general surface of the map-area is almost level. Passing inland from the St. Lawrence, two escarpments are met with, the first, half a mile from the river, about fifty feet high, and the second, at a short distance, rising another hundred feet, beyond which the altitude is maintained at an average of 150 feet. This uniformity is broken only by three water-courses: the Sainte-Anne and La Che- vrotière rivers and Belisle brook, which have worn their beds more or less deeply into the Quaternary deposits, and have reached the Palm- ozoic rocks in a few places.
To the north of Deschambault village, the limestone has been quarried for many years. There are several operating quarries near Saint-Marc-des-Carrières which supply building stone of excellent quality, known as Deschambault stone or Saint-Marc stone. Else- where in the parish of Deschambault, also, there are a few small quarries, now abandoned. 48 Quebec Bureau of Mines 1934
FIELD WORK AND ACKNOWLEDGMENTS In many places near Saint-Marc, the limestone beds have been truncated and exposed to a great depth, both by the Sainte-Anne river, near the Saint-Olivier bridge, and in the quarries, from some of which stone has been extracted for a hundred years. As a result, there is fairly complete information on the stratigraphy in this section of the map-area. To the south of Saint-Marc, the limestone disappears beneath a mantle of superficial deposits and only reappears at the surface in the second range of Deschambault, where outcrops are almost continuous from the Canadian Pacific railway station at Deschambault to the church of Grondines. Our work during the 1934 field season was devoted especially to the study of the Palæozoic formations in the Deschambault section of the map-area, with the object of determining the extent and indus- trial possibilities of the limestone and its relationship to the under- lying granite and overlying shale, as well as the stratigraphical position of each of the sedimentary formations. In this work, I was assisted in the field by Walston A. Vachon, graduate of l'École Supérieure de Chimie de Québec, who rendered efficient service. I am especially indebted to Dr. R. Ruedemann, Palæontologist of New York State, who very kindly examined the fossils collected from the Utica shale; and to Dr. Alice E. Wilson, of the Geological Survey of Canada, who rendered similar assistance in the case of the Ordovician brachiopods. PRE VIOUS WORK IN THE AREA The limestones of the area, and particularly the occurrences in the vicinity of Saint-Marc-des-Carrières, have been studied from very early times. In the Geology of Canada, 1863 (pp. 152, 272), Logan made note of the presence of an anticlinal to the north of Deschambault church, and gave a summary description of the lime- stone which outcrops in the area. A. P. Low, who visited the region in 18890, mentions the exten- sive development of quarries in the fifth range of La Chevrotière, and notes the difference between the stone quarried at Saint-Marc- des-Carrières and that of the second range of Deschambault, where already at that time he. found abandoned quarries. 0 Low, A. P., Geol. Surv. Can., Ann. Rept., Vol. V, Part I, 1890-91, p. 69L. Part D Pakeozoic of Deschambault Region 49
In 1914, Wm. A. Parks® examined, from the commercial and industrial point of view, the stone furnished by the several companies operating quarries at Saint-Marc-des-Carrières. In his preliminary report on the limestones of the provinces of Quebec and Ontario, M. F. Goudge® outlines the distribution of the Trenton series in the Province of Quebec, and gives a chemical analysis of the Saint-Marc-des-Carrières limestone, with a brief description of the rock. In the summer of 1930, Parks studied the attitude of the strata underlying the lowlands of the St. Lawrence with the view of determ- ining the structural folds which might be favourable to the accumula- tion of natural gas. His report ® is accompanied by a geological map (No. 112) of the valley of the St. Lawrence from Montreal to Quebec. In 1933, Goudge published the results of a detailed study of Canadian limestones used as building stone ®. Among the occur- rences and quarries described are those of the Saint-Marc-des-Car- rières area. This report also contains much data on the quarrying and dressing of building stone.
GEOLOGY
The formations met with in the map-area comprise crystalline rocks of the Precambrian, and overlying sedimentary beds of Ordo- vician age (see accompanying map, Figure 1). Unconsolidated glacial and post-glacial deposits cover a large part of the area, to an extent that rock outcrops are rather restricted. The following table gives the succession of the several formations:
® Parks, Wm. A., Report on the Building and Ornamental Stones of Canada, Vol. III, Province of Quebec; Mines Branch, Dept. of Mines, Ottawa, 1914, pp. 87-93. ® Goudge, M. F., Preliminary Report on the Limestones of Quebec and Ontario; Mines Branch, Dept. of Mines, Ottawa, Pub. No. 682, 1927, pp. 13-17. ® Parks, Wm. A., Natural Gas in the St. Lawrence Valley, Quebec; Que. Bur. Mines, Ann. Rept., Part D, 1930, pp. 3-98. ® Goudge, M. F., Canadian Limestones for Building Purposes, Mines Branch, Dept. of Mines, Ottawa, Pub. No. 733, 1933, pp. 38-54.
4
50 Quebec Bureau of Mines 1934
TABLE OF FORMATIONS
Recent swamp and alluvial deposits QUATERNARY Stratified sands and clays Glacial débris, boulder clay
Long period of erosion
Utica Clay shales PALÆOZOIC Trenton Limestones and thin beds of shale
Long period of erosion
PRE CAMBRIAN Granite and gneiss
PRECAMBRIAN
The object of the field work being primarily the study of the sedimentary formations, only secondary attention was given to the Precambrian rocks. These, in the district examined, form a spur which, in its southern extension, reaches to within a mile and a half of the St. Lawrence. A. P. Low® describes these Precambrian rocks as follows:
"The rocks of this spur, and its eastern extension, are seen in numerous exposures along the roads running back from the St. Law- rence. These show generally fine-grained grey and pink orthoclase- biotite gneiss arranged in alternate thin bands, the grey being the most common, and often containing black hornblende in association with mica, while the red is formed chiefly of red orthoclase and quartz. Both varieties often hold small dark red garnets. Associated with these fine-grained bands are others of coarser texture".
® Loc. cit., p. 15L. Part D Palaeozoic of Deschambault Region 51
PALIEOZOI C
A.—TRENTON LIMESTONE
1.—DESCHAMBAULT AREA: A general survey of the position of the outcrops of limestone in the parish of Deschambault (see Figure 1) shows that the Trenton forms a band extending from La Chevrotière river to the railway station at Deschambault.
In the area mapped, the most westerly outcrop appears in the bed of La Chevrotière river, at about a quarter of a mile north of the bridge on the provincial highway. Between La Chevrotière river and Belisle brook, a dome of limestone rises slightly above the level of the plain. The outcrop, which is a quarter of a mile in width, extends over lots 117 to 122. On lot 119, now owned by Anthime Sauva- geau, this limestone was formerly quarried and utilized, it is said, for the building of bridges on the line of the Canadian Pacific railway. The quarry measures scarcely 50 feet in diameter and is only 4 to 5 feet deep. Individual beds of the limestone are barely eight inches thick, and are separated by thin, black clay seams. Fossils are very numer- ous, those observed being referred to the following species:
Prasopora si7nulatrix Ulrich Platystrophia amoena MeEwan Calymene senaria Conrad Schizocrania sp. Dalmanella rogata (Sardeson) Rafinesquina alternata (Emmons)
East of this outcrop, the limestone is seen again in the bed of Belisle brook, and from here outcrops continue for a distance of two miles. They are well seen along the two roads transverse to the river, one to the east and the other to the west of the village of Des- chambault, as well as on each side of the second range road.
The thickness of the limestone in this area is not known. All the quarries are relatively shallow, the deepest being that on lot 239, present property of J. E. Massicotte. This quarry was worked about
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nte Deschambault J/ Scale of Miles _ o Yz I z S T £chelle de Milles
i!1\,..I Granite, gneiss Limestone (Trenton) Schists (Utica) -iI\< (Precambrian) • QF Fossil locality Quarry Outcrop Figure 1.—Geological map of Deschambault region. Part D Palœozoic of Deschambault Region 53 six years ago; it was connected with the line of the Canadian Pacific railway by a spur 700 to 800 feet in length. Starting at the top, the lithological succession is as follows: Dark grey limestone, fine-grained 212 feet Grey limestone, coarser 3K feet Bluish-grey limestone, in places black 10 feet The lower part of the quarry is inaccessible, being filled with water to a depth of 10 to 12 feet. To the south and southeast of this quarry are two other excava- tions, from which stone was taken formerly for local needs. The first is on the property of Herménégilde Saint-Amant, lot 222 of the second range of the parish of Deschambault, and the second on lot 85, property of Jules Perreault. The thickness of limestone exposed by these quarries does not exceed fifteen feet. Individual beds range from three inches to a maximum of twelve inches in thickness, each bed marked from the succeeding one by a thin argillaceous parting. The limestone is generally bituminous and emits a fetid odour under the blow of the hammer. Frequently, small vugs filled with black petroleum may be seen in the rock. In places, also, there are nodules or bands of chert. In some outcrops, the limestone is dissected by pronounced joints, the walls of which are as much as twelve inches apart for a depth of seven to eight feet. It appears that these fissures, which are due to a partial solution of the limestone, may be of rather recent age, for they have not been filled by glacial débris, nor by deposits of the Champlain sea. The limestone is everywhere highly fossiliferous and an abundant fauna can be collected, particularly at those places where the rock has been quarried. However, as the beds are almost horizontal, and as all the quarries are shallow, the observed fauna is practically uniform wherever the limestones have been examined. The following is a preliminary list of the species collected in this area:
CRINOIDS Abundant stems BRYOZOA Prasopora simvlatrix Ulrich Escharopora sp. Pachydictya sp Quebec Bureau of Mines 1934
BRACHIOPODS Lingula sp. Lingula cf. obtusa Hall Lingula quebecensis Billings Cf. Crania Pholidops trentonensis Hall Dalmanella rogata (Sardeson) Dinorthis pectinella (Emmons) Sowerbyella sericea (Sowerby) Rafinesquina alternata (Emmons) Rafinesquina rugosa acuta Wilson Parastrophia hemiplicata Hall Rhynchotrema increbescens (Hall) Zygospira recurvirostris (Hall)
GASTROPODS Phragmolites cornpressus Conrad
TRILOBITES Calymene senaria Conrad Ceraurus dentatus Raymond and Barton Pterygometopus callicephalras (Hall)
OSTRACODS Leperditia sp.
Of the species listed, Rafinesquina rugosa acuta is restricted, according to Dr. Alice E. Wilson, to the Lower Trenton; all the others have a greater vertical extension. It would appear, then, that in the second range of the parish of Deschambault, the Middle Trenton and Upper Trenton beds have been eroded away. Eastward from the Canadian Pacific railway station at Descham- bault, there are no exposures of limestone for a distance of two miles, where, near the road which leads inland between Portneuf and Des- chambault, limestone outcrops as a lens on the edge of the granite. I1 is well exposed along the Canadian National (formerly Transconti- nental) railway. Beyond this, the exposures are of the overlying Utica shale, but limestone again appears at the surface not far from Portneuf station. On cadastral lot No. 207 of Portneuf, there is a small working, now abandoned, where the limestone was formerly quarried for use in making lime. Its location is shown in Figure 3. It is thus apparent that, between Deschambault and Portneuf, the limestone does not form a continuous band in contact with the granite, as indicated in previous geological maps. Part D Palaeozoic of Deschambault Region 55
Ten samples of limestone from the Dcschambault area were analyzed in the laboratory of the Bureau of Mines, under the direction of Maurice Archambault, with the following results:
ANALYSES OF LIMESTONES FROM DESCHAMPAULT AREA
Si02 Fe203 ,11203 Ca3 CaCO3 MgCO3 Total Ca0 MgO Ca0/ Sample (PO4)2 MgO % % % % % % % % % No 1 .5.19 0.20 0.08 0.14 90.93 1.67 98.21 51.02 0.80 64/1 No.2 1.00 0.12 0.05 0 13 96.99 1.42 99.41 54.41 0.68 80/1 No. 3 0.56 0.09 0.10 0.09 97.35 1.55 99.74 54.60 0.44 74/1 No. 4 0.26 0.14 0.00 0,09 98,35 1.00 99-84 55.15 0.48 115/1 No. 5 0.77 l).12 0.07 0,13 95.89 1.51 98.49 53.80 0.72 75-1 No. 6 2.80 (1,21 0.06 0.20 93.96 1.40 98 63 52.76 0.67 79/1 No.7 1.44 0.08 0.00 0.14 95.44 1.32 98.42 53.55 0.63 85/1 No.8 3.25 0.11 0.14 0.13 93.46 1.44 98.53 52.44 0.69 76/1
No.9 3.21 0.30 0.00 0.11 93.07 1.51 98.20 52.21 0.72 73/1 No. 10 1.36 0.14 0.00 0.15 96.89 0.90 99.44 54.37 0.43 127/1
No. 1.-Surface specimen, from lot 296. No. 8.-Giroux quarry, lot 239, twelve feet below No. 2.-Sauvageau quarry, lot 119, upper beds surface No. 3.-Saint-Arrant quarry, lot. 222. upper beds No. 9.-Surface specimen, from lot 245, near the No. 4.-Perreault quarry, lot 85, upper beds granite No. 5.-Perreault quarry, lot 85, twelve feet lower No. 10.-Richard quarry, lot 207, parish of Port- No. 6.-Giroux quarry, lot 239, upper beds neuf No. 7.-Giroux quarry, lot 239, four feet below surface
2.-SAINT-MARC AREA: The most northerly outcrop of limestone in what is here referred to as the Deschambault area is on Belisle brook, at the point where the brook crosses the road leading inland, to the west of Deschambault village. North of this point, for a distance of two miles, no outcrop breaks through the mantle of surface deposits. After this interval, limestone is again exposed on each side of the road leading to Saint- Marc-des-Carrières, at about half a mile to the southeast of the village, and, northeast from this point, a whole row of quarries extends along the road, particularly to the west of Saint-Marc village. The general character of the rock in all these quarries is very much the same. Goudge 0 gives the following description of the stone: "The St. Marc limestone is composed largely of fossil frag- ments-crinoid stems and fragments of bryozoa being particularly prominent. This fossiliferous character is well shown on polished
~r Op cit.. 1933, p. 42. 56 Quebec Bureau vf Mines 1934
surfaces. The stone varies slightly in grain, some being moder- ately fine-grained and some moderately coarse, but the average is medium-grained. The colour of the freshly broken stone varies with the grain, the finer grained being darker than the coarser stone, but in general it is a light brownish-grey. The percentage of pore space is very low and the stone is very compact. Occasional vugs filled with black petroleum are present in some of the beds in the western quarries. If an oil-filled vug is en- countered during the dressing of a block, a poultice of lime paste is useful in removing the stain. In common with other Quebec limestones, Deschambault stone contains very thin films of black, bituminous shale, approximately parallel to the bedding, at inter- vals of from 2 to 8 inches. In some beds they are scarcely notice- able. The stone is not cross-bedded but the strata vary some- what in thickness from place to place, and the bedding planes are quite uneven; these features together with the fact that the joints intersect at oblique angles makes it very difficult to secure rectangular blocks. "On account of its chemical purity, much of the waste stone can be marketed, large quantities of it being sold to pulp mills and for agricultural purposes. St. Marc is also an important lime-producing centre and for a number of years much of the waste stone was utilized by lime plants, but the lime companies are now operating quarries of their own". The following analysis, made by C. L. O'Brian of the Mines Branch, Ottawa, and reproduced from Goudge's report (p. 41), shows the composition of a representative sample of the limestone from this area. As will be seen, it is very high in calcium carbonate, and con- tains less magnesia than any of the Deschambault samples whose analyses are given in the table on page 55.
ANALYSLS OF REPRESENTATIVE SAMPLE OF SAINT-MARC LIMESTONE Silica (Si02) 0 36 Ferric oxide (Fe203) 0 15 Alumina (A1203) 0 01 Calcium phosphate (Ca3(PO4)2) 0 35 Calcium carbonate (CaCO3) 97.59 Magnesium carbonate (MgCO3) 0 69 99.15 Sulphur (S) 0.02 Part D Palaeozoic of Deschambault Region 57
From the palœontological point of view, the limestones of the Saint-Marc area do not present any notable differences from those of the Deschambault area to the south. Following is a list of the fossils collected:
BRYOZOA Pachydictygisp. BRACHIOPODS Orbiculoidea sp. Dinorthis sp. Dinorthis pectinella (Emmons) Dalmanella rogata (Sardeson) Rafinesquina sp. Rafinesquina alternata (Emmons) Sowerbyella sericea (Sowerby) Triplecia sp. Parastrophia hemiplicata Hall C amarella sp. FE LE C YPO DS A mbonychia cf. amygdalina Hall GASTROPODS Bucania. sp. Phragmolites sp. Conularia trenlonensis Hall TRILOBITES Bumastus sp. Bumastus cf. billingsi Raymond and Narraway Remopleu.rides sp. Bathyrus sp. Calymene senaria Conrad Ceraua-us sp Pterygometopus sp. Pterygometopus callicephalus (Hall) OSTRA COD S Leperditia sp.
None of these species are characteristic of a determined horizon of the Trenton, and hence they do not permit the establishment of a difference between the Saint-Marc limestone and that of the Des- chambault area. From the lithological point of view, however, and from their general aspect, it would seem that the Saint-Marc beds may be higher in the series than those exposed in the Deschambault area. The succession given by Goudge T for the quarry of Martineau et Fils, Ltée. (Morrison Quarry Co.) is as follows:
CO Op. cit., 1933, p. 45.
58 Quebec Bureau of Mines 1934
Figure 2.—Sketch-map showing Belisle brook where it crosses the fault.
3 to 6 feet Soil 0 to 10 feet ..Inferior stone 2 to 4 inches Sandy clay seam 13 to 16 inches Building-stone bed 17 to 20 inches 16 29 to 30 inches 34 to 35 inches
12 to 16 inches " Thin sandy clay seam Hard fine-grained limestone
Thus, the limestone beds quarried in the Saint-Marc area are thicker than those of Deschambault. On the whole, the clay seams are farther apart and the rock is more suitable for the purposes of chemical industry. B: UTICA SHALE
In the area studied, the Utica shale does not form any very extended outcrops. At no point was it seen directly in contact with the Trenton limestone. Part D Palaeozoic of Deschambault Region 59
About a mile and a quarter north of Deschambault church, the black shale appears below an escarpment that trends from southwest to northeast. Following that direction, the shale, containing grap- tolites, outcrops on lots 88 to 84 of the first range of Deschambault, and also on lot 246. It is seen again along the road leading to the west of the village, fairly near to the granite spur, and at several points more to the east (sec accompanying map, Figure 1).
The best outcrop of shale occurs about a mile west of the rail- way station of Portneuf. Keele, in his report on the clay and shale deposits of the Province®, gives the following description:
"There is a cutting about 12 to 15 feet deep in Utica shales, near Portneuf station on the National Transcontinental railway !now Canadian National!. The shale occurs in very thin layers. It is nearly black in colour when fresh, but bleaches to grey on exposure to weathering, so that it probably contains some carbon- aceous matter. This shale is not plastic when finely ground and mixed with water, therefore it cannot be worked by the wet- moulded process for brick manufacture. When made up dry- pressed and burned to cone 03, a strong, steel-hard body is pro- duced, with an absorption of 9 per cent. The colour is dark buff, with light buff specks, giving a rather pleasing effect for face brick".
The section in Figure 3 shows the attitude of the formations at this locality, and it will be seen that the thickness of the shale is more than two hundred feet.
Wherever it outcrops in this area, the shale is highly fossiliferous, but the fauim does not appear very varied. Well preserved grapto- lites are particularly abundant. The several beds exposed in the various outcrops examined have yielded identical species, the list. of which follows:
®i Keele J., Preliminary Report on the Clay and Shale Deposits of the Province of Quebec. Geol. Surv. Can., Memoir 64, 1915, p. 24.
60 Quebec Bureau of Mines 1934
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Figure 3.—Plan and section of formations on lot 207, parish of Portneuf. Part D Palmozoic of Deschambault Region 61
GRAPTOLITES Climacograptus sp. Climacograptus typicalis Hall Clirnacograplus t ypicalis Hall var. Climacograptus caudatus Lapworth Dicranograptus nichol.soni Hopkinson Glossograptus quadrimucronatus (Hall) var. appraximatus Ruedemann. Lasiograptus eucharis (Hall) CHAETO POI)5 Serpulites angustifolius Hall BRACHIOPODS Leptobolus insignis Hall Schizocrania tilosa Hall TRILOBITES Triarthrus eatoni Hall
Dr. R. Ruedemann, who kindly examined the fossils collected, reports that they are typical of the Utica, with the exception of Cli- macograptus caudatus, which has not hitherto been recorded in this formation (letter of March, 1935). This particular specimen of Cli- macograptus caudatus was found in a bed situated stratigraphically about 200 feet above others which are recognized as of Utica age by their fauna. It must be concluded, therefore, that Climacograptus caudatus disappeared in the valley of the St. Lawrence a little later than in the New York area.
STRUCTURE FOLDING: Trenton Limestone. In most outcrops, the beds of Trenton lime- stone are almost horizontal. Locally, however, there has been gentle folding. Near the railway station at Deschambault there is an anti- cline which has been long known ®, whose axis trends southeast- northwest. It is an unsymmetrical fold, with the beds on the west limb dipping gently at from 3 to 5 degrees, and those on the east inclined much more steeply, with dip even exceeding 25 degrees. Where the limestone is next exposed farther east— if the small lens of limestone bordering the granite, previously referred to, is dis- regarded the beds are still more steeply inclined. Thus, in the small quarry situated on lot 207 of the parish of Portneuf (see Figure 3), the angle of dip is 60 degrees to the south-southwest.
®i Geology of Canada, 1863, pp. 152, 272. 62 Quebec Bureau of Mines 1934
Utica Shale.—In all the exposures seen, the Utica shale dips south or south-southwest at angles ranging between 25 and 60 degrees.
FAULTING: On the accompanying map (Figure 1), a fault has been indicated, starting from the mouth of La Chevrotière river and striking north- east to and beyond the railway station at Portneuf. Evidence for this fault is as follows: 1.—Starting at the point where the assumed fault crosses Belisle brook, and extending right across the map-area to its eastern boundary, there is an escarpment with a height from 10 to 30 feet. From Belisle brook to the vicinity of Deschambault station, on the Canadian Pacific railway, this escarpment is formed of limestone, and beyond that of granite. The limestone beds are almost horizontal and, as stated on an earlier page, they are of Lower Trenton age, the Upper Trenton and Utica shale formerly overlying them having been re- moved by erosion. At the foot of this escarpment, Utica shale is exposed, with a dip of 25 to 30 degrees towards the south-southwest. Its presence here, and with dip so different from that of the limestone, may be interpreted as due to a break similar to that at the Mont- morency falls, near Quebec city. 2.—At the point where the line of the Canadian National (former Great Northern) railway crosses Belisle brook, near the road west of Deschambault church, outcrops of horizontally bedded limestone may be seen in the bed of the brook (see Figure 2). About 400 feet from this locality, Clovis Naud, proprietor of a flour mill, had a hole drilled to a depth of 145 feet. It passed through 60 feet of surface deposits and 85 feet of shale, without, however, reaching the limestone. Such a difference in the level of the limestone between two points so near to one another can be explained only by the presence of a fault. 3.—Figure 3 shows, in section and in plan, the formations occur- ring on lot 207, parish of Portneuf, at about one mile west of Portneuf station. As may be seen by this sketch, the limestone and shale here abut against the granite. This locality is in the line of strike, westward, of the escarpment previously mentioned. It may be noted that this fault has a direction parallel to two faults in the area farther south, which are shown on map No. 112, accom- panying the report by Parks in Part D of the Annual Report of the Bureau for 1930.