Wales: British regional geology by M.F. Howells. British geological survey, Nottingham, 2007. No. of pages: 230. ISBN 978-085272584-9 (Paperback)
WALES: BRITISH REGIONAL GEOLOGY by M.F.Howells. British Geological Survey, Nottingham, 2007. No. of pages: 230. Price: £ 18-00. ISBN 978-085272584-9 (Paperback).
Fiona E. Fearnhead*, * Department of Earth and Planetary Sciences, Birkbeck College, Malet Street, Bloomsbury, London, WC1E 7HX, UK
This detailed, new, regional geology guide is designed for geology students, enlightened amateurs and professionals who need insight and an overview of the complexities of the geology of Wales. The book is divided into 10 chapters: ‘Pre-cambrian’, ‘Cambrian’, ‘Ordovician’, ‘Silurian,’ ‘Devonian’, ‘Carboniferous’, ‘Mesozoic’, ‘Cainozoic’ and ‘Glacial and Post-glacial Deposits’; the tenth, final chapter is entitled as ‘Geology and Man’. It replaces earlier editions of this series in which North and South Wales were described in separate volumes. Three-quarters of the book is dedicated to the Lower Palaeozoic rocks, reflecting their dominance in Wales.
The book is fully and beautifully illustrated with relevant maps and diagrams, with a good choice of colours for illustrations. Diagrams are clearly annotated with pertinent information. A clear and beautifully produced map of Wales and adjacent area (adapted from the BGS 1:625000 Bedrock Geology, UK South 2007) rests in the plastic insert of the inside back cover, making it easily accessible for practical use when required.
The book is extremely well written. However, there are some inconsistencies such as the lack of inflections, for example, for Pridoli in early chapters (with the exception of Llŷn) and the sudden appearance of inflections for Přídolí on p. 90. One inaccuracy is that Tortworth is in Gloucestershire, not in Somerset.
The book gives a good ‘meaty’ overview of the geology and helpfully marks formations in bold, for example, Cerig Formation. However, in the chapter for the Silurian, the Llandovery formations are not clearly defined. For example, at Llandovery the type section is described as ‘divided into eight formations comprising mudstone and fine-grained sandstone with parallel and cross-laminations, accompanied by a few thin, fine-grained, micaceous shelly sandstones and calcareous sandstones that are deeply weathered to rottenstones’ (p. 76). Sadly, the eight formations are not clearly set out and units such as the Haverfordwest Mudstone, Haverfordwest Sandstone and Newlands Farm formations are ignored completely. Reflecting a personal bias, I think the Llandovery would have benefitted from the same treatment as other chapters. Vertical sections of the early Llandovery strata would have clarified present understanding, identified the problems and provided a useful tool for future research.
The photograph of the Three Chimneys at Marloes Sands perhaps should have been annotated for clarity. Fossils are rare at this locality ‘except as rottenstones’ (p. 86); however, it would have been more accurate to say that only well preserved fossils are rare. Abundant fossils are to be found preserved as external moulds and within the Gray Sandstone Group, and fine crinoid columnals preserved as calcite are to be found.
Finally, there are some additional and very interesting maps: the tectonic map (p. 94.) and a metamorphic map (p. 96.). A truly useful resource and a labour of love by the author, M.F. Howells, following his retirement.