Microscopie examination and comparison of chemical analyses have indicated the possibility of the common origin of the rocks of the thesis area and that of Mount Royal. However, final proof was obtained using the Barth system of petrographic calculations. These show the tinguaite to be a differentiate of the nepheline-syenite, while the dike rocks have been derived from the original essexite magma.

Mapping and petrographic studies within the Shield area have been extended to a point where integration of the mass of data included in published reports and maps should provide a much more accurate view of conditions prevailing during the Precambrian time than was heretofore possible. This thesis is a contribution toward that end. The particular task undertaken was a regional study of the character and distribution of acid volcanics within that part of the Southern Shield referred to by Gill (1949) as the “Superior Province”. The method followed was to assemble all published information relating to acid volcanics; to plot on maps such data as can be shown graphically and to summarize the rest. Five maps have been prepared of various districts in the Province where these rocks occur. Descriptions of occurrences, including Tables of Formations and references have been assembled in an Appendix.

The area covered by this thesis is in the province of Ontario between longitudes 76° 00’ to 76° 30’ west and latitudes 44° 45’ to 45° 00’ north. It includes most of Lanark and part of Leeds counties. Within the county of Lanark there are parts of the townships of Dalhousie, Drummond, Montague, Bathurst, North Elmsley, South Sherbrooke and the entire township of North Burgess. The county of Leeds includes parts of the townships of North Crosby, South Burgess, South Elmsley, Bastard and Kitley. The largest towns in the map-area are: Perth, the county town of Lanark, which is in the central part of the area and has a population of 4,500, and Smiths Falls which is on the eastern edge of the map-area and has a population of 8,500. Perth was founded in 1816 by Scottish soldiers disbanded after the war of 1812 and was for a long time a military town. Highway No. 15 from Ottawa and Highway No. 7 from Toronto join at Perth, which is at 50 miles from Ottawa. Highway No. 29 from Brockville and Highway No. 15 from Kingston cross the southeastern part of the map-area. A network of secondary roads provides easy access to all parts of the map-area and allowed detailed mapping to be made in a few months. Lot fences also form a good grid for surveying. The map-area can also be reached by railroad, the Canadian Pacific line from Montreal to Toronto going through Perth and Smiths Falls. Other railroads connect Smiths Falls with Brockville, Kingston, Carleton Place and Ottawa. [...]

The Burnt Creek - Goodwood area, represents a part of the main ore zone on the contiguous exploration concessions of the Hollinger North Shore Exploration Company, in New Quebec, and of the Labrador Mining and Exploration Company, in Labrador, Newfoundland. The concessions cover the southern part of the “Labrador Trough”, a geological unit made up of folded and faulted sedimentary and volcanic series of late Precambrian Age. (Figure 1 ) This paper deals with a detailed study of the Kaniapiskau system with special reference to the Sokaman iron formation, the most important economic member of that system, in an area where large concentrations of iron ore ( as hematite and goethite ) occur within the iron formation. Field work conducted by the writer at various localities in the area during the summers of 1947, 1948 and 1949, particularly between Wishart Lake and Irony Mountain and to the north in the vicinity of Goodwood deposit ( Figure 2 ), together with field data of other members of the staff, form the basis of this study. The field work was followed by laboratory investigations at McGill University and at the University of Minnesota. A map of the vicinity of Burnt Creek accompanies this report to illustrate the major features of the geology of the area.

The map-area straddles the crest of a major anticline within the Purcell Mountains of British Columbia. It is underlain by a conformable series of precambrian quartzite, limestone, and slate members. One limb of the major anticline is disturbed locally by a zone of minor folding. This minor folding has caused considerable plastic flowage in a thick limestone member of the series. As a result of the flowage, the limestone beds are intricately folded and have developed a distinctive layered structure. The origin of this layering by metamorphic differentiation is discussed. A series of quartz veins, containing small amounts of gold, occurs along the crest of the major anticline principally within the uppermost quartzite member. These appear to have been deposited from solutions which invaded fissures formed as a result of the folding.

The Sawyer Lake area is in central Labrador, between Sawyer lake and Comeback lake. It forms a northeast trending parallelogram about twenty miles long and three to five miles wide, covering in all about eighty-five square miles. It lies between latitudes 54° 26’ and 54°43’ north and longitudes 65°50’ and 66°0’ west.

The Ymir area (long. 117° - 117°15’, lat. 49°15'- 49°30') lies just southeast of Nelson in the southern part of British Columbia. It includes 300 square miles of the area lying between Kootenay Lake and the Columbia River (Figure I). The western part of the area is easily accessible from the Ymir-Salmo road which runs nearly north-south along the western border of the map area. A branch line of the Great Northern Railroad follows along this road.

During the summer of 1949 the writer carried out exploration work on a group of eight mining claims, known as the McCuaig group. These claims are located in Pardee Township, Thunder Bay District, Ontario. The property may be reached by means of a gravel road two miles long that branches off to the north from the Scott Highway at a point forty miles west of Fort William. The Scott Highway is a paved highway between Duluth, Minnesota, and Fort William, Ontario.

The Suffield mine is in the Eastern Townships of the Province of Quebec and is situated five miles southwest of the city of Sherbrooke. The mine is the property of the Suffield Metals Corporation Limited, a wholy owned subsidiary of Ascot Metals Corporation Limited, and is a producer of zinc, copper, lead, silver and gold. A range of hills known as the Stoke Mountain range and locally called the Ascot ridge extends southwest from the mine to lake Memphremagog, and northeast, through the city of Sherbrooke, to Lake St. Francis.

This paper is an attempt to discuss Chazy reefs and reef builders of the Montreal district, and their relationships to other reefs, and reef builders of the Pre-Cambrian, and Palaeozoic rocks. Before the subject can be discussed, the problem as to what is a reef should be settled. Definitions have varied depending on the approach to the subject, whether from the point of view of a geologist, or zoologist, whether reefs past, or present were being considered, or what the reef was composed of.