The Sedimentary Record of Sea-Level Change

Darrel G.F. Long

Department of Earth Sciences, Laurentian University, Sudbury, Ontario P3E 2C6

dlong@laurentian.ca



Edited by Angela L. Coe (Open University, UK) Cambridge University Press, 40 West 20th Street, New York. NY 10011-4211 Publication date: 2003; 287 p. ISBN 0-521-83111-3 (Hardback - $110.00 US); 0-521-53824-4 (Paperback - $ 50.00 US).

1 This colourfully illustrated book, edited by Angela L. Coe (Open University), with contributions by Dan W.J. Bosence (Royal Holloway, London), Kevin D. Church (Open University), Stephen S. Flint (Liverpool), John A. Howell (Bergen) and R. Chris L. Wilson (Open University), is based in part on a third-year level course in sequence stratigraphy developed at the Open University. In this textbook the authors use a highly rhetorical approach, with numerous posed questions and answers to reinforce their lessons. This may be effective in distance education courses delivered on DVD and videotape, but does not work well in print. Arguments are presented using well drafted, but over-simplified case models, with too few citations of the pertinent literature. Although short bibliographies are provided at the end of each section, they lack context. In keeping with the distance education model of the Open University, the text is supported by a website with downloadable examples of selected illustrations, worked examples and links to other resources.

2 The book is divided into four parts, each with numbered subsections. In the first part Coe presents a brief introduction to sedimentary rocks as a record of Earth processes, using an imaginary meandering river in flood as a metaphor for sedimentary processes. The angular unconformity at Jedburgh, UK, first described by James Hutton, is then used to introduce concepts of time within the sedimentary record. This is followed by a brief discussion of the methods for division of the stratigraphic record and geological time, with reviews of litho- and biostratigraphy, radiometric dating, magneto- and chemo-stratigraphy. She also examines astronomic influences on stratigraphy through climate change, and implies that Milankovich processes can only be extended with confidence to 35 Ma. To illustrate how sea-level change can be detected in the rock record, Coe and Church use Ryan and Pitman's observations on the catastrophic flooding of the Black Sea, which may have been the historic event that formed the basis for later accounts of Noah's Flood. They show how, at least during glacial intervals, oxygen isotopes can be used as a proxy for eustatic sea-level change, and how the stratigraphic record of sea-level change is also influenced by tectonics and sediment supply.

3 In part 2, Coe and Church provide a clear explanation of their version of sequence stratigraphy, which incorporates the use of the Falling Stage System Tract (FSST) to record sedimentation between the onset and end of base level fall. In their model the sequence boundaries are placed between the peak of the High Stand System Tract (HST) and the FSST, consistent withthe nomenclature of Haq et al., rather than that of Hunt and Tucker, who established the FSST nomenclature and placed the sequence boundary between the FFST and Lowstand System Tract. The authors manage to avoid much of the inherent confusion in current scientific literature on sequence stratigraphy by not fully explaining the background and evolution of sequence stratigraphic nomenclature and models. This may make it easier to explain how the sedimentary record can be used as a proxy for sea-level change, but does not prepare students for the subtle differences in meaning of terms in the current spectrum of sequence stratigraphic models.

4 In part 3, Howell and Flint provide an extensive and well-illustrated discussion of the Cretaceous siliciclastic sequences at Book Cliff, Utah. This begins with a comprehensive description of the stratigraphy and sedimentary facies, using modern analogues, followed by a discussion of parasequences, sequences and systems tracts. This forms the basis for their final section on the sequence stratigraphic evolution of the Book Cliff succession.

5 In the final section Bosence and Wilson discuss the complexities of sequence stratigraphy in carbonate settings and introduce the use of numeric stratigraphic modeling for facies prediction. Bosence then illustrates the application of these sequence models using the Late Miocene of Mallorca as an example of a rimmed platform, and the Upper Jurassic of Spain as an example of a carbonate ramp.

6 Although this book is intended for undergraduate and graduate courses, as well as professional geoscientists, I would not recommend it as an upper year undergraduate or graduate text. Despite the exemplary use of simplified case studies, and excellent coloured photographs and diagrams, it lacks the scope of the GAC's Short Course Notes 16, which in my opinion provides a far more comprehensive coverage of the topic.