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Applied Geochronology
Tectonophysics - Elsevier Printed in The Netherlands
Publishing
Company, Amsterdam
BOOK REVIEW Applied Geochronology. 267 pp., 53 illus.,
E.I. Hamilton. Academic 52 tables, 59 s.
Press,
London,
1965,
Scientific books with a practical background serve a useful purpose at least when they have been written clearly and understandably. When they discuss methods currently used by a small group of specialists, they should be written as explicitly as possible, especially when directed at a wide circle of readers who have to apply these methods, but are only partly or not at all familiar with them. The book under discussion is one of this kind. As stated by the author in the preface, it has been written specifically for geologists, and it tries to fill the gap which exists between “those who obtain the results and the geologists who wish to apply these to conventional geological problems”. Seen in this light, it is indeed a very useful book, because the methods described not only give the general procedures and historical background, but also deal with the applications for dating geological material. The main result of the introduction of radiometric age determination has been the discovery of the enormous length of geological time. The accuracy of this conclusion is scientifically hardly debated any longer. The problems have become more specific: is the base of the Cambrian at 500, 570, or 600 million years, is the Cambrian a long period, the Silurian a comparatively short one, are isotopic ages good guides in Pleistocene geochronology? It is important to realize that isotopic age determination, and intelligent interpretation of the combined results. In this way, the “error” of some percent, which is generally given with a radiometric age determination, is no handicap. The isotopic data may prevent errors in correlation of a much higher percentage (seen against a scale of real time). Such errors are not uncommon if only traditional geochronological methods are used. Nevertheless, it is a good thing that the book shows plainly what the sources are of the “error” percentage. Gaining understanding is basic in scientific cooperation. The methods currently in use are discussed in detail, such as the potassiumargon method, the rubidium-strontium method and the uraniumthorium-lead method, but more deviating ones are not given. The samariumneodynium method, for example, has not been described, although according to the author, it would appear possible to use this method to date rare-earth rich minerals, particularly those found in alkaline rocks. This, however, cannot be considered as a serious flaw in the book, but more important is the fact that it is doubtful if the work really appeals to the geologists. There is a very short and comprehensive introduction by L.H. Ahrens on the comparative geochemistry of potassium, rubidium, calcium, argon, strontium, uranium, thorium and lead, and also a historical introduction by the author. In chapter 2, dealing with general methods, mathematics suddenly crop up and unfortunately this is something not generally welcomed by the average geologist. In the same chapter, the mass spectrometer has been described in a way which does not enable the reader to get a very clear understanding Tectonophysics,
2 (5) (1965) 453454
BOOK REVLEW
454
of it. In a book of this kind, illustrations can play a most essential part in explaining what is discussed in the text. The author is correct in having presented wonderful photographs of two mass spectrometers, but the reference in the text to details of these illustrations is missing. Instead, the reader is overwhelmed with technical terms, which undoubtedly serve their purpose, but which will be incomprehensible to the geologist who is trying to get an insight into the aim and function of the instrument in question. There are some minor shortcomings, such as the use of the names Maestrichtian and Palaeocene, in the geological time scale on p.224, instead of Maastrichtian and Paleocene, but the major fault is that in a book, directed at people who are not familiar with the ~pl~cations of the methods, the reader is referred to a reference list contpining only author’s names, years of publication and the sources given. Titles of books would have been of primary importance in this case to enable outsiders to make a selection for further reading. On the whole, although the book serves a good purpose in describing the application of geochronology for dating rocks and minerals, one gets the impression that the author has done his job, by placing himself too much at one end of the subject, and by starting from assumptions that are too general when describing methods and instruments. An odd accidental circumstance is the fact that the work was published in the same year in which A. Holmes, “the father of the modern geological time scale” died. A.L.J.
Tectonophysics,
2 (5) (1965) 453-454
STOFFELS
Publishing
Company, Amsterdam
BOOK REVIEW Applied Geochronology. 267 pp., 53 illus.,
E.I. Hamilton. Academic 52 tables, 59 s.
Press,
London,
1965,
Scientific books with a practical background serve a useful purpose at least when they have been written clearly and understandably. When they discuss methods currently used by a small group of specialists, they should be written as explicitly as possible, especially when directed at a wide circle of readers who have to apply these methods, but are only partly or not at all familiar with them. The book under discussion is one of this kind. As stated by the author in the preface, it has been written specifically for geologists, and it tries to fill the gap which exists between “those who obtain the results and the geologists who wish to apply these to conventional geological problems”. Seen in this light, it is indeed a very useful book, because the methods described not only give the general procedures and historical background, but also deal with the applications for dating geological material. The main result of the introduction of radiometric age determination has been the discovery of the enormous length of geological time. The accuracy of this conclusion is scientifically hardly debated any longer. The problems have become more specific: is the base of the Cambrian at 500, 570, or 600 million years, is the Cambrian a long period, the Silurian a comparatively short one, are isotopic ages good guides in Pleistocene geochronology? It is important to realize that isotopic age determination, and intelligent interpretation of the combined results. In this way, the “error” of some percent, which is generally given with a radiometric age determination, is no handicap. The isotopic data may prevent errors in correlation of a much higher percentage (seen against a scale of real time). Such errors are not uncommon if only traditional geochronological methods are used. Nevertheless, it is a good thing that the book shows plainly what the sources are of the “error” percentage. Gaining understanding is basic in scientific cooperation. The methods currently in use are discussed in detail, such as the potassiumargon method, the rubidium-strontium method and the uraniumthorium-lead method, but more deviating ones are not given. The samariumneodynium method, for example, has not been described, although according to the author, it would appear possible to use this method to date rare-earth rich minerals, particularly those found in alkaline rocks. This, however, cannot be considered as a serious flaw in the book, but more important is the fact that it is doubtful if the work really appeals to the geologists. There is a very short and comprehensive introduction by L.H. Ahrens on the comparative geochemistry of potassium, rubidium, calcium, argon, strontium, uranium, thorium and lead, and also a historical introduction by the author. In chapter 2, dealing with general methods, mathematics suddenly crop up and unfortunately this is something not generally welcomed by the average geologist. In the same chapter, the mass spectrometer has been described in a way which does not enable the reader to get a very clear understanding Tectonophysics,
2 (5) (1965) 453454
BOOK REVLEW
454
of it. In a book of this kind, illustrations can play a most essential part in explaining what is discussed in the text. The author is correct in having presented wonderful photographs of two mass spectrometers, but the reference in the text to details of these illustrations is missing. Instead, the reader is overwhelmed with technical terms, which undoubtedly serve their purpose, but which will be incomprehensible to the geologist who is trying to get an insight into the aim and function of the instrument in question. There are some minor shortcomings, such as the use of the names Maestrichtian and Palaeocene, in the geological time scale on p.224, instead of Maastrichtian and Paleocene, but the major fault is that in a book, directed at people who are not familiar with the ~pl~cations of the methods, the reader is referred to a reference list contpining only author’s names, years of publication and the sources given. Titles of books would have been of primary importance in this case to enable outsiders to make a selection for further reading. On the whole, although the book serves a good purpose in describing the application of geochronology for dating rocks and minerals, one gets the impression that the author has done his job, by placing himself too much at one end of the subject, and by starting from assumptions that are too general when describing methods and instruments. An odd accidental circumstance is the fact that the work was published in the same year in which A. Holmes, “the father of the modern geological time scale” died. A.L.J.
Tectonophysics,
2 (5) (1965) 453-454
STOFFELS