Logging the Chalk by Rory N. Mortimore. Whittles Publishing, Caithness, Scotland, 2014. No. of pages: x + 357. Price: UK£135.00. ISBN 978‐184995‐098‐5 (hardback)

Abstract

When this hefty book fell on my doormat, my first thought was that it could not have been written by a better man. Rory Mortimore succeeds in presenting a splendid overview of decades of his research into the Chalk (mid- and Late Cretaceous), with the focus on the British Chalk (mostly onshore, but also offshore). However, there are comparisons with Upper Cretaceous strata across mainland Europe (mostly France, plus northern Germany and the Maastricht area in the Netherlands). During 30 years, Mortimore has described and interpreted over 3000 chalk cores and visited hundreds of temporary outcrops – ample experience, I would say! This is a comprehensive guide to the Chalk, describing this rock type in detail for the benefit of geologists, (geotechnical) engineers and, also, collectors of fossils. Chalk in the field is of prime importance – things can be seen out there and information gained will help in interpreting cores (best done in bright light, preferably sunlight!). Core loss (around flint levels), nodular chalks and fractures are all discussed. In fact, because of the sheer wealth of detail, some chapters may become very dense and difficult to read. Recent data, obtained in close co-operation with engineers, hydrogeologists and reservoir geologists, have resulted in a much better picture of Chalk. Throughout the book the standard lithostratigraphy (it took over 25 years to reach consensus over this) is used and, where appropriate, CIRIA (Construction Industry Research and Information Association) classification is supplied as well. There are seven chapters and two appendices (three more can be downloaded from the publisher's website). The first describes, classifies and interprets the Chalk, mainly for engineering purposes. Special attention is paid to sheet flints (often missed in cores) and trace fossils, in particular Zoophycos, as well as other features essential in core interpretation. Several examples of macrofossils (cephalopods, inoceramid bivalves, echinoderms) that can aid in logging are provided. Numerous full-colour pictures, with clear labelling (sedimentary features, lithostratigraphic interpretations) are supplied in all chapters. All logs are neat, with colour coding to assist in correlative schemes. Chapters 2–4 discuss the stratigraphic framework for the southern, transitional and northern Chalk ‘provinces’, respectively. In Chapter 5 we get our feet wet, entering the Central Graben and North Sea chalks. Correlative schemes with German, Danish and Dutch chalk sections are included. Chapter 6 focuses on weathering styles in cores and in the field (CIRIA grades; see also Appendix 1), with examples of groundwater staining, karst phenomena, dissolution pipes and relic pipes. The final chapter looks to the future, discussing the impact of optical and acoustic televiewers, and gamma and resistivity logs on Chalk studies – it concludes with several recommendations. Appendix 2 will be very useful in describing flints during logging. Strangely enough there is no reference here to work carried out by the late Felder brothers between 1970 and 2005 near Maastricht, nor to Hans Zijlstra's studies of the Upper Cretaceous–lowermost Paleocene of mainland Europe. Editorial control appears to have been tight, but some taxon names are spelt wrongly, both in the text and in figures; other misspellings refer to non-English names. In summary, this book deserves a wide readership. In fact, every Chalk worker should have a copy. I would certainly have benefitted from it when interpreting the >25 cores of the A2 motorway tunnel at Maastricht several years ago.