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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.

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