Abstract
THE publication of Prof. Johannsen's four-volume “Petrography” was completed by the appearance of the last volume in 1938. Notices of the work have appeared in NATURE, 129, 636 (1932); 132, 691 (1933); and 142, 495 (1938). The first volume, dealing mainly with the textures and classification of the igneous rocks, now appears in a second edition. In his preface to this new edition, Johannsen quotes a statement made by Tom Barth in connexion with certain proposed modifications of rock classifications: “One should always be careful not to spoil a good idea by undue improvements”. Apparently adopting this advice, Johannsen has made very few alterations in his revision. Apart from a few minor improvements of the text and additions to the biographies of prominent petrographers, he has been content to make only the following changes. Tha summary of Hodge's quantitative system of rock classification has been replaced by short accounts of Lacroix's (1933) and Troger's (1935) systems. A few pages are added dealing with Niggli's (1931) modification of Johannsen's classification and with Andreatta's (1937) modification of Niggli's modification; these few pages are headed with a figure of what appears to be a monkey-wrench-a pleasant gibe which most readers will appreciate. A new appendix, giving the definitions of some 750 rocks described in the other three volumes of the work, has been added, but the other appendixes and tables remain exactly as in the 1931 edition. Teuscher's (193?) method of describing granularity is summarized, and Fersmann's (1928) views on the origin of graphic texture are briefly mentioned. With the exceptions noted, no reference to new work appearing since 1931 is made.
A Descriptive Petrography of the Igneous Rocks
Vol. I: Introduction, Textures, Classifications and Glossary. By Prof. Albert Johannsen. Second edition. Pp. xxiv + 318. (Chicago: University of Chicago Press; London: Cambridge University Press, 1939.) 27s. net.
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Geology. Nature 145, 1007 (1940). https://doi.org/10.1038/1451007a0
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DOI: https://doi.org/10.1038/1451007a0