Guide books of excursions in Canada1-10 . eologicalcolumn and the equivalent of the Fundamental Gneissof Logan. This gneiss, as Lawson conclusively demon-strated, is intruded through the oldest sedimentary rocks(Keewatin group) of that region in the form of greatbatholiths. This work marked an epoch in the interpre-tation of Pre-Cambrian geology not only in Canadabut in all North America. Then followed, in 1893, Adams demonstration thatLogans Upper Laurentian did not exist as an inde-pendent geological series, the anorthosites, which wereconsidered as constituting its main features, being inre
Guide books of excursions in Canada1-10 . eologicalcolumn and the equivalent of the Fundamental Gneissof Logan. This gneiss, as Lawson conclusively demon-strated, is intruded through the oldest sedimentary rocks(Keewatin group) of that region in the form of greatbatholiths. This work marked an epoch in the interpre-tation of Pre-Cambrian geology not only in Canadabut in all North America. Then followed, in 1893, Adams demonstration thatLogans Upper Laurentian did not exist as an inde-pendent geological series, the anorthosites, which wereconsidered as constituting its main features, being inreality great intrusive masses. In a subsequent (1895)paper he showed that two distinct classes of rocks couldbe distinguished in the remaining portion of the Laurentian,the first being beyond all doubt igneous rocks and thesecond consisting of highly altered rocks of aqueous origin. From the results of these investigations, it becameevident that if a satisfactory knowledge of the origin,character, structure and relations of the Laurentian. IO succession in Eastern Canada was to be obtained, it wouldbe necessary to select some large area of these rocks andmap it in much greater detail than had hitherto beenattempted, the examinations in the field being supple-mented by thorough petrographical study of the variousrock types represented in the area. The area selectedfor such detailed study was that designated as SheetNo. 118 (Haliburton sheet) of the Ontario series ofgeological maps which are being issued by the GeologicalSurvey of Canada. As will be seen by the accompanyingsketch map, this district lies close to the margin of thegreat Northern Protaxis, north of Lake Ontario and tothe east of Georgian bay. Dr. Frank D. Adams, with whom Dr. Alfred E. Barlowwas subsequently associated, undertook for the GeologicalSurvey a detailed geological study of this region, con-cerning the geological structure of which nothing wasknown at that time but which, from its position, promisedto yiel
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectgeology, bookyear1913
