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The last deglaciation: Absolute and radiocarbon chronologies
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
594
Book Reviews
sought by examining the record of ~4C secular variations (Lal et al.), the independent evidence for cosmonuclide production variations provided by analysis of ~°Be content of ice cores (Raisbeck et al.; Beer et al.) and variations in geomagnetic field intensity (Salis and Bonhommet Mazaud et al.). This section positively underlines the view that a clearer understanding of the physics of the systems will go a long way to illuminating geological enigmas. Nevertheless there are some conundrums to unravel still, such as the lack of support from the preliminary ~0Be results for the theory that cosmogenic production rate changes account for the radiocarbon production variations in the atmosphere during the last glacial/interglacial transition. The third section of the book is not concerned with chronology per se, but with 'Climatic Changes During the Last Deglaciation'. In some respects, some of these chapters illustrate why progress in chronology is essential, if we are to recognise loss leaders. Thus, for example, Jouzel et al. suggest there may be a 'Younger Dryas' climatic event identifiable in the Antarctic ice cores, despite the fact that the suggested age significantly pre-dates the YD in the northern hemisphere. It is unfortunate that the term 'Younger Dryas' is used in this context before the equivalence in age can be properly tested, as it simply invites the construction of a 'house of cards'. However, Jouzei et al. do provide arguments as to why they believe the cooling event was synchronous in both hemispheres and include a number of fascinating observations on C H 4 and dust variations that are clearly germane to the overall understanding of events during the last deglaciation. Other contributions in this section also present useful summaries of ideas concerning the roles of the 'Nordic heat pump' (Broecker), meltwater anomalies and sea surface temperatures in the N. Atlantic (Sarnthein et al.; Duplessy et al.; Fisher), radiocarbon reservoir ages in the oceans (Southon et al.), climatic changes in NW Africa (Basse and Fontes) and effects of the Younger Dryas event in Europe and eastern North America (Peteet). Overall the ideas contained in this book far outweigh in importance any limitations perceived by this reviewer. It is just so valuable to have all of this material gathered into one volume. Yet there is one niggling criticism that did not subside, and that is the extent to which consideration was given to the intended market. Practitioners in one field will know that most of the material contained here has already been published and debated quite extensively and they, like me, will already hold files containing more up-to-date developments on much of what is covered. Thus the book will best serve as a store of information for those on the fringes of the subject or coming new to it. Here is where I felt the editors missed a golden opportunity to make it not just an interesting addition to the library shelves, but an essential, instructive standard. If only they had included a general introduction to the problems, an integration (inter-comparison) of the
results, an insight into work in progress, an assessment of future potential in the light of the proceedings, and an evaluation of the success (or otherwise) of the workshop. There is no effort on the part of the editors to put the material into this kind of context. This is a pity. In the end, one is left wondering whether the participants interacted at the meeting. The aim, according to a short Prologue to the book, was to 'discuss the timing of the last deglaciation in order to provide a common absolute chronological framework for the numerous researchers in the field'. How far did they succeed? Perhaps we must await a sequel.
References Johnsen, S.J., Ciausen, H.B. et al. (1992). Irregular glacial interstadials recorded in a new Greenland ice core. Nature, 359, 311-313. Wohlfarth, B., BjOrk, S. et al. (1993). AMS dating Swedish varved clays of the last glacial/interglacial transition and the potential difficulties of calibrating between Late Weichselian 'absolute' chronologies. Boreas, 22, 113-128. J. John Lowe
Department of Geography, Royal Holloway, University of London, Egham, Surrey, TW20 OEX, U.K.
Quaternary Landscapes, edited by C.K. Shane and E.J. Cushing, Bellhaven Press, 1991. ISBN 1-85293207-4, £29.50 hardback, 209 pp. This compact volume comprises six review papers that were originally presented at a symposium held in May 1988 to celebrate the work of the Limnological Research Center at the University of Minnesota and to honour Herbert E. Wright Jr its first permanent director, at the time of his retirement. The range of topics is a reflection of the breadth of Quaternary research undertaken by the centre under Wright's direction. Each paper is written by a leading specialist in the field in question and each manages to cite Wright's work at least once. Other than this, however, there seems little to connect the six disparate chapters. The editors presumably saw this as a problem, as they have contrived a connection via the drawing on the cover and frontispiece, an illustration of early hunters attacking a group of mammoths next to a lake and peat bog, with a coniferous forest in the middle background and an ice-sheet terminus in the distance. A panel showing detail from this drawing appears at the head of each chapter. The title of the volume also seems misleading; the topics are generally related to palaeoclimate, vegetation, physical processes and research methodology, with none of the chapters concentrating on geomorphology. Notwithstanding the lack of a coherent theme, the individual contributions are of a very high standard. The first is a thought-provoking review of the origins of food production in western Asia and eastern North America by Patty Jo Watson, written in typical festschrift style.
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
594
Book Reviews
sought by examining the record of ~4C secular variations (Lal et al.), the independent evidence for cosmonuclide production variations provided by analysis of ~°Be content of ice cores (Raisbeck et al.; Beer et al.) and variations in geomagnetic field intensity (Salis and Bonhommet Mazaud et al.). This section positively underlines the view that a clearer understanding of the physics of the systems will go a long way to illuminating geological enigmas. Nevertheless there are some conundrums to unravel still, such as the lack of support from the preliminary ~0Be results for the theory that cosmogenic production rate changes account for the radiocarbon production variations in the atmosphere during the last glacial/interglacial transition. The third section of the book is not concerned with chronology per se, but with 'Climatic Changes During the Last Deglaciation'. In some respects, some of these chapters illustrate why progress in chronology is essential, if we are to recognise loss leaders. Thus, for example, Jouzel et al. suggest there may be a 'Younger Dryas' climatic event identifiable in the Antarctic ice cores, despite the fact that the suggested age significantly pre-dates the YD in the northern hemisphere. It is unfortunate that the term 'Younger Dryas' is used in this context before the equivalence in age can be properly tested, as it simply invites the construction of a 'house of cards'. However, Jouzei et al. do provide arguments as to why they believe the cooling event was synchronous in both hemispheres and include a number of fascinating observations on C H 4 and dust variations that are clearly germane to the overall understanding of events during the last deglaciation. Other contributions in this section also present useful summaries of ideas concerning the roles of the 'Nordic heat pump' (Broecker), meltwater anomalies and sea surface temperatures in the N. Atlantic (Sarnthein et al.; Duplessy et al.; Fisher), radiocarbon reservoir ages in the oceans (Southon et al.), climatic changes in NW Africa (Basse and Fontes) and effects of the Younger Dryas event in Europe and eastern North America (Peteet). Overall the ideas contained in this book far outweigh in importance any limitations perceived by this reviewer. It is just so valuable to have all of this material gathered into one volume. Yet there is one niggling criticism that did not subside, and that is the extent to which consideration was given to the intended market. Practitioners in one field will know that most of the material contained here has already been published and debated quite extensively and they, like me, will already hold files containing more up-to-date developments on much of what is covered. Thus the book will best serve as a store of information for those on the fringes of the subject or coming new to it. Here is where I felt the editors missed a golden opportunity to make it not just an interesting addition to the library shelves, but an essential, instructive standard. If only they had included a general introduction to the problems, an integration (inter-comparison) of the
results, an insight into work in progress, an assessment of future potential in the light of the proceedings, and an evaluation of the success (or otherwise) of the workshop. There is no effort on the part of the editors to put the material into this kind of context. This is a pity. In the end, one is left wondering whether the participants interacted at the meeting. The aim, according to a short Prologue to the book, was to 'discuss the timing of the last deglaciation in order to provide a common absolute chronological framework for the numerous researchers in the field'. How far did they succeed? Perhaps we must await a sequel.
References Johnsen, S.J., Ciausen, H.B. et al. (1992). Irregular glacial interstadials recorded in a new Greenland ice core. Nature, 359, 311-313. Wohlfarth, B., BjOrk, S. et al. (1993). AMS dating Swedish varved clays of the last glacial/interglacial transition and the potential difficulties of calibrating between Late Weichselian 'absolute' chronologies. Boreas, 22, 113-128. J. John Lowe
Department of Geography, Royal Holloway, University of London, Egham, Surrey, TW20 OEX, U.K.
Quaternary Landscapes, edited by C.K. Shane and E.J. Cushing, Bellhaven Press, 1991. ISBN 1-85293207-4, £29.50 hardback, 209 pp. This compact volume comprises six review papers that were originally presented at a symposium held in May 1988 to celebrate the work of the Limnological Research Center at the University of Minnesota and to honour Herbert E. Wright Jr its first permanent director, at the time of his retirement. The range of topics is a reflection of the breadth of Quaternary research undertaken by the centre under Wright's direction. Each paper is written by a leading specialist in the field in question and each manages to cite Wright's work at least once. Other than this, however, there seems little to connect the six disparate chapters. The editors presumably saw this as a problem, as they have contrived a connection via the drawing on the cover and frontispiece, an illustration of early hunters attacking a group of mammoths next to a lake and peat bog, with a coniferous forest in the middle background and an ice-sheet terminus in the distance. A panel showing detail from this drawing appears at the head of each chapter. The title of the volume also seems misleading; the topics are generally related to palaeoclimate, vegetation, physical processes and research methodology, with none of the chapters concentrating on geomorphology. Notwithstanding the lack of a coherent theme, the individual contributions are of a very high standard. The first is a thought-provoking review of the origins of food production in western Asia and eastern North America by Patty Jo Watson, written in typical festschrift style.