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Quaternary sediments
592
Book Reviews
is little mention of the vast, later literature bearing on the geophysical connotations of isostasy, the account is in accord with the inherently historical nature of neotectonics, and with its focus on changing patterns of stress and crustal response. Yet seismicity, stress and heat flow, though not sufficient for an understanding of the neotectonics of North America, are evidently an essential preliminary to it. Slemmons had explained that the overwhelmingly large accumulation of palaeoseismic data could not be analysed in time for inclusion in the book. The view that palaeoseismology is an integral part of neotectonics is regrettably not widely held in Europe, where it is still possible to write learnedly about young movements and fossil landforms without any hard data about their seismic context. This fine book clearly demonstrates what the Old World sorely needs. C. Vita Finzi
Department of Geological Sciences, University College, University of London, Gower St., London, WCIE 6BT, U.K. Quaternary Sediments, S.J. Gale and P.J. Hoare, Belhaven Press, London, 1991. ISBN 1-85293-017-9, £42 hardback, 323 pp. Here, proclaims the dustjacket, we have a book that 'brings together many of the physical and chemical laboratory methods' for analysing 'sediments, soils and weathering products . . . . the most powerful means available of reconstructing the environmental history of the Quaternary Period'. Most readers will hold this to be a 'self-evident truth'; thus, it is necessary to adopt the mantle of a sceptic in order to properly appraise
Quaternary Sediments. The book consists of chapters on the laboratory analysis of Quaternary materials (1% of total page length), sample documentation, preparation and storage (4%), basic laboratory techniques and procedures (12%), physical composition and analysis of regolith materials (54%), chemical composition and analysis of regolith materials (19%), and appendices (8%). together with a skeletal index (2%). References terminate each chapter; both the references and the occasional line drawings are useful but somewhat idiosyncratically chosen. The authors justify a lengthy introduction to basic laboratory skills on the grounds that undergraduates no longer receive sufficient formal training in laboratory techniques (a view that will find much sympathy among those teaching 'experimentally challenged' classes). Indeed, the book is most effective as a basic practical manual. For example, explanations of sampling theory, and of accuracy and error in measurement, will be especially useful to the inexperienced. However, more experienced undergraduate and postgraduate
students of physical geography or geology will recognise weaknesses in the detailed accounts of procedures for selected analyses such as fabric, particle size, clast petrography, heavy mineralogy and several of the simpler bulk geochemical techniques. The authors have selected techniques for inclusion under stringent, self-imposed constraints of relative cost and hazard. As a result, procedures given for core analyses such as particle size and heavy mineralogy are in effect censored; technically less demanding, cheaper or less hazardous substances or equipment are substituted for more widely accepted materials. Although this decision is defensible, unfortunately the authors have not indicated where they have made such modifications, nor do they point out that the resulting data are likely to be inferior. One striking example is the recommended use of a hand-held pipette for assessing particle size under a particularly challenging sampling schedule. Perhaps the most serious casualty, rejected primarily on the grounds of unacceptable complexity, is the micromorphoiogical study of petrographic thin-sections. As the only means of investigating inter-particle relationships, this is essential for reconstructing postdepositional histories. Also eliminated, presumably on the same grounds, are ICP spectrometry and all dating techniques, including those specifically developed for the Quaternary such as radiocarbon and thermoluminescence. Surely it is necessary for undergraduates to understand high-tech analyses, even if they are not permitted to use them? However, discussions of some of the techniques that are covered are unusually perceptive, suggesting that the authors are experienced in their use. Colour data are raised to a genuinely scientific level. Also, unlike most of its competitors, this volume explicitly recognises that particle size distributions are often polymodal and that fabrics are often weak: both characteristics challenge accepted statistical parameters. Unfortunately, the multivariate statistical techniques that are so valuable for summarising large bodies of disparate data are mentioned only in passing and absent from the index. The most serious challenge to Gale and Hoare is posed by uniformitarianism; what criteria, other than age, distinguish Quaternary sediments from those of equivalent time periods earlier in the geological record (say the Westphalian B)? Gale and Hoare offer only two criteria in their introduction; Quaternary sediments usually are not lithified, and the ratio of terrestrial to marine deposits is unusually high. To these can be added the high proportions of surface or near-surface deposits of poor long-term preservation potential, and of ice-related deposits. But these are mere qualitative trends. The only qualitative distinguishing criterion is ignored, namely Man's influence on the environment during the late Quaternary in general and the Hoiocene in particular. No room is found for the analysis of anthropogenic (or indeed biogenic) materials. To summarise, this book contains much of interest but largely fails to achieve its laudable dual aims
Book Reviews of elucidating appropriate analytical methods and explaining their applications. In the former role it is greatly outpriced by Avery and Bascomb (1974) and Briggs' (1977), outdetailed by Carver (1971), and outgunned by other more specialist volumes published by the Soil Survey of England and Wales and the Quaternary Research Association. As most of these works are ageing rapidly, there remains a vacant niche for a user-friendly students manual, but it should be published as a cheap paperback. Applications and interpretations are well covered by Lowe and Walker (1984) for the Quaternary and Leeder (1982) for the broader geological context. Here again, there may be room for a future volume that uses detailed case-studies to bridge the wide gap between field collection and synthetic interpretation. In either case, a broader range of analytical mathematical techniques will be needed if the integrated geoanalytical approach advocated by Hoare and Gale is to be fully exploited and the excitement of cutting-edge Quaternary Science conveyed to the novice.
References Avery, B.W. and Bascomb, C.J. (1974). Soil Survey Laboratory Methods. Soil Survey of England and Wales Technical Monograph 6, Harpenden, 83 pp. Briggs, D. (1977). Sources and Methods in Geography: Sediments. Butterworths, London, 192 pp. Carver, R.E., ed. (1971). Procedures in Sedimentary Petrology. Wiley, New York, 653 pp. Leeder, M.R. (1982). Sedimentology: Process and Product. Allen and Unwin, London. 344 pp. Lowe, J.J. and Walker, M.J.C. (1984). Reconstructing Quaternary Environments. Longman, London, 389 pp. Orpah S. Farrington Department of Geology, Birkbeck College, University of London, Malet Street, London, W C I E 7HX, U.K.
The Last Deglaciation: Absolute and Radiocarbon Chronologies, edited by Edouard Bard and Wallace S. Broecker, Springer, Berlin and New York, 1992. ISBN 3-540-53123-8 and 0-387-53123-8, DM 228,344 pp. This is the proceedings of a NATO Advanced Research Workshop held in Erice, Sicily, in 1990, and the volume is published within NATO's ASI Series I 'Global Environmental Change'. The workshop was organised in order to examine the problems of establishing a precise chronological framework for the last deglaciation. The meeting was both timely and essential, since it is commonly accepted that limitations in current dating methods, and especially the lack of a common calendrical standard, present the most serious obstacles to resolving the complex and very abrupt environmental changes of the last glacial/interglacial transition. The topic is, of course, a fascinating one. The last deglaciation can be studied in immense detail, and theories abound as to the relative importance
593
of the various dynamic links and mechanisms that appear to have orchestrated events. In truth, however, the theories are very difficult to test without precise chronometers of appropriate resolution. Intricate they may be, but recent models of global changes during the last deglaciation still present rather scrambled images, mainly due to the unsatisfactory performance of the radiocarbon method. Current wisdom preaches that the development of an alternative chronometer and/or calibration of the radiocarbon timescale will solve the problems. So, what are the prospects, and when might we expect unscrambled pictures to emerge? This book will tantalise those seeking answers to these questions. It is edited by two scientists hugely respected for their contributions to the study of the period, and it contains material covering the range of methods considered to be the most likely to deliver us from the current chronological jam. It is, therefore, an essential acquisition for those with an interest in the last deglaciation or dating methods in general. But there are some disappointments, common to most of these publications produced rapidly to disseminate the results of an international workshop. These include the usual irritants of varying print fonts, detail of explanation and level of illustration between the individual contributions. Others, however, are a little more fundamental than that. The first point to note is that only the first (approximately) half of the book, consisting of two sections, is strictly focused on the book's title. The first section, entitled 'Radiocarbon and Absolute Chronologies', presents recent results from those attempting to calibrate or up-stage the radiocarbon method, using tree-rings (Kromer and Becker), ice cores (Johnsen and Dansgaard), varve sequences (Bj6rk et al.; Lotter et al.; Rozanski et al.; Zolitschka et al.) and mass spectrometry measures of 23trFh/23"*U ages of coral (Bard et al.). Each of these methods, it is claimed, will ultimately provide a more reliable basis than that of the radiocarbon method for estimating time and timing during the last deglaciation. One thing most of them have in common - - they all indicate that radiocarbon dating under-estimates, quite significantly, the age of the period. Thus, for example, the Younger Dryas/Holocene boundary, radiocarbon dated to about 10,000 BP, is estimated to around 10,970 BP by dendrochronology, to ca. 11,550 BP by ice cores and to ca. 10,900 years by varve chronology from Sweden. Note, however, that these last two estimates do not come from the material presented in this book, which is less well defined in this respect, but from subsequent publications (Johnsen et al., 1992; Wohlfarth et al., in press). This illustrates one of the inevitable draw-backs of writing a book on such a fast-moving topic: it was almost out-of-date at publication release! The second section examines 'Cosmonuclide Production Changes During the Past'. If radiocarbon activity has varied in the past, what caused this, and can the variations be modelled and corrected for? Answers to these and other related questions are being
Book Reviews
is little mention of the vast, later literature bearing on the geophysical connotations of isostasy, the account is in accord with the inherently historical nature of neotectonics, and with its focus on changing patterns of stress and crustal response. Yet seismicity, stress and heat flow, though not sufficient for an understanding of the neotectonics of North America, are evidently an essential preliminary to it. Slemmons had explained that the overwhelmingly large accumulation of palaeoseismic data could not be analysed in time for inclusion in the book. The view that palaeoseismology is an integral part of neotectonics is regrettably not widely held in Europe, where it is still possible to write learnedly about young movements and fossil landforms without any hard data about their seismic context. This fine book clearly demonstrates what the Old World sorely needs. C. Vita Finzi
Department of Geological Sciences, University College, University of London, Gower St., London, WCIE 6BT, U.K. Quaternary Sediments, S.J. Gale and P.J. Hoare, Belhaven Press, London, 1991. ISBN 1-85293-017-9, £42 hardback, 323 pp. Here, proclaims the dustjacket, we have a book that 'brings together many of the physical and chemical laboratory methods' for analysing 'sediments, soils and weathering products . . . . the most powerful means available of reconstructing the environmental history of the Quaternary Period'. Most readers will hold this to be a 'self-evident truth'; thus, it is necessary to adopt the mantle of a sceptic in order to properly appraise
Quaternary Sediments. The book consists of chapters on the laboratory analysis of Quaternary materials (1% of total page length), sample documentation, preparation and storage (4%), basic laboratory techniques and procedures (12%), physical composition and analysis of regolith materials (54%), chemical composition and analysis of regolith materials (19%), and appendices (8%). together with a skeletal index (2%). References terminate each chapter; both the references and the occasional line drawings are useful but somewhat idiosyncratically chosen. The authors justify a lengthy introduction to basic laboratory skills on the grounds that undergraduates no longer receive sufficient formal training in laboratory techniques (a view that will find much sympathy among those teaching 'experimentally challenged' classes). Indeed, the book is most effective as a basic practical manual. For example, explanations of sampling theory, and of accuracy and error in measurement, will be especially useful to the inexperienced. However, more experienced undergraduate and postgraduate
students of physical geography or geology will recognise weaknesses in the detailed accounts of procedures for selected analyses such as fabric, particle size, clast petrography, heavy mineralogy and several of the simpler bulk geochemical techniques. The authors have selected techniques for inclusion under stringent, self-imposed constraints of relative cost and hazard. As a result, procedures given for core analyses such as particle size and heavy mineralogy are in effect censored; technically less demanding, cheaper or less hazardous substances or equipment are substituted for more widely accepted materials. Although this decision is defensible, unfortunately the authors have not indicated where they have made such modifications, nor do they point out that the resulting data are likely to be inferior. One striking example is the recommended use of a hand-held pipette for assessing particle size under a particularly challenging sampling schedule. Perhaps the most serious casualty, rejected primarily on the grounds of unacceptable complexity, is the micromorphoiogical study of petrographic thin-sections. As the only means of investigating inter-particle relationships, this is essential for reconstructing postdepositional histories. Also eliminated, presumably on the same grounds, are ICP spectrometry and all dating techniques, including those specifically developed for the Quaternary such as radiocarbon and thermoluminescence. Surely it is necessary for undergraduates to understand high-tech analyses, even if they are not permitted to use them? However, discussions of some of the techniques that are covered are unusually perceptive, suggesting that the authors are experienced in their use. Colour data are raised to a genuinely scientific level. Also, unlike most of its competitors, this volume explicitly recognises that particle size distributions are often polymodal and that fabrics are often weak: both characteristics challenge accepted statistical parameters. Unfortunately, the multivariate statistical techniques that are so valuable for summarising large bodies of disparate data are mentioned only in passing and absent from the index. The most serious challenge to Gale and Hoare is posed by uniformitarianism; what criteria, other than age, distinguish Quaternary sediments from those of equivalent time periods earlier in the geological record (say the Westphalian B)? Gale and Hoare offer only two criteria in their introduction; Quaternary sediments usually are not lithified, and the ratio of terrestrial to marine deposits is unusually high. To these can be added the high proportions of surface or near-surface deposits of poor long-term preservation potential, and of ice-related deposits. But these are mere qualitative trends. The only qualitative distinguishing criterion is ignored, namely Man's influence on the environment during the late Quaternary in general and the Hoiocene in particular. No room is found for the analysis of anthropogenic (or indeed biogenic) materials. To summarise, this book contains much of interest but largely fails to achieve its laudable dual aims
Book Reviews of elucidating appropriate analytical methods and explaining their applications. In the former role it is greatly outpriced by Avery and Bascomb (1974) and Briggs' (1977), outdetailed by Carver (1971), and outgunned by other more specialist volumes published by the Soil Survey of England and Wales and the Quaternary Research Association. As most of these works are ageing rapidly, there remains a vacant niche for a user-friendly students manual, but it should be published as a cheap paperback. Applications and interpretations are well covered by Lowe and Walker (1984) for the Quaternary and Leeder (1982) for the broader geological context. Here again, there may be room for a future volume that uses detailed case-studies to bridge the wide gap between field collection and synthetic interpretation. In either case, a broader range of analytical mathematical techniques will be needed if the integrated geoanalytical approach advocated by Hoare and Gale is to be fully exploited and the excitement of cutting-edge Quaternary Science conveyed to the novice.
References Avery, B.W. and Bascomb, C.J. (1974). Soil Survey Laboratory Methods. Soil Survey of England and Wales Technical Monograph 6, Harpenden, 83 pp. Briggs, D. (1977). Sources and Methods in Geography: Sediments. Butterworths, London, 192 pp. Carver, R.E., ed. (1971). Procedures in Sedimentary Petrology. Wiley, New York, 653 pp. Leeder, M.R. (1982). Sedimentology: Process and Product. Allen and Unwin, London. 344 pp. Lowe, J.J. and Walker, M.J.C. (1984). Reconstructing Quaternary Environments. Longman, London, 389 pp. Orpah S. Farrington Department of Geology, Birkbeck College, University of London, Malet Street, London, W C I E 7HX, U.K.
The Last Deglaciation: Absolute and Radiocarbon Chronologies, edited by Edouard Bard and Wallace S. Broecker, Springer, Berlin and New York, 1992. ISBN 3-540-53123-8 and 0-387-53123-8, DM 228,344 pp. This is the proceedings of a NATO Advanced Research Workshop held in Erice, Sicily, in 1990, and the volume is published within NATO's ASI Series I 'Global Environmental Change'. The workshop was organised in order to examine the problems of establishing a precise chronological framework for the last deglaciation. The meeting was both timely and essential, since it is commonly accepted that limitations in current dating methods, and especially the lack of a common calendrical standard, present the most serious obstacles to resolving the complex and very abrupt environmental changes of the last glacial/interglacial transition. The topic is, of course, a fascinating one. The last deglaciation can be studied in immense detail, and theories abound as to the relative importance
593
of the various dynamic links and mechanisms that appear to have orchestrated events. In truth, however, the theories are very difficult to test without precise chronometers of appropriate resolution. Intricate they may be, but recent models of global changes during the last deglaciation still present rather scrambled images, mainly due to the unsatisfactory performance of the radiocarbon method. Current wisdom preaches that the development of an alternative chronometer and/or calibration of the radiocarbon timescale will solve the problems. So, what are the prospects, and when might we expect unscrambled pictures to emerge? This book will tantalise those seeking answers to these questions. It is edited by two scientists hugely respected for their contributions to the study of the period, and it contains material covering the range of methods considered to be the most likely to deliver us from the current chronological jam. It is, therefore, an essential acquisition for those with an interest in the last deglaciation or dating methods in general. But there are some disappointments, common to most of these publications produced rapidly to disseminate the results of an international workshop. These include the usual irritants of varying print fonts, detail of explanation and level of illustration between the individual contributions. Others, however, are a little more fundamental than that. The first point to note is that only the first (approximately) half of the book, consisting of two sections, is strictly focused on the book's title. The first section, entitled 'Radiocarbon and Absolute Chronologies', presents recent results from those attempting to calibrate or up-stage the radiocarbon method, using tree-rings (Kromer and Becker), ice cores (Johnsen and Dansgaard), varve sequences (Bj6rk et al.; Lotter et al.; Rozanski et al.; Zolitschka et al.) and mass spectrometry measures of 23trFh/23"*U ages of coral (Bard et al.). Each of these methods, it is claimed, will ultimately provide a more reliable basis than that of the radiocarbon method for estimating time and timing during the last deglaciation. One thing most of them have in common - - they all indicate that radiocarbon dating under-estimates, quite significantly, the age of the period. Thus, for example, the Younger Dryas/Holocene boundary, radiocarbon dated to about 10,000 BP, is estimated to around 10,970 BP by dendrochronology, to ca. 11,550 BP by ice cores and to ca. 10,900 years by varve chronology from Sweden. Note, however, that these last two estimates do not come from the material presented in this book, which is less well defined in this respect, but from subsequent publications (Johnsen et al., 1992; Wohlfarth et al., in press). This illustrates one of the inevitable draw-backs of writing a book on such a fast-moving topic: it was almost out-of-date at publication release! The second section examines 'Cosmonuclide Production Changes During the Past'. If radiocarbon activity has varied in the past, what caused this, and can the variations be modelled and corrected for? Answers to these and other related questions are being