Geology of Site Investigation Boreholes from Hong Kong, published in May 2004, is a book by Chris Fletcher, which draws on his broad geological experiences in Hong Kong, first as Head of the Hong Kong Geological Survey of GEO, CED and latterly, prior to his recent departure from Hong Kong, as both a consultant (Arrow Geoscience Limited) and Director of the Applied Geoscience Centre (AGC), in the Department of Earth Sciences of The University of Hong Kong (DES, HKU). The book is cosponsored by the AGC, the Hong Kong Construction Association (Site Investigation Contractors Committee), and the Association of Geotechnical and Geoenvironmental Specialists (Hong Kong).
Described by the author as ‘A Practical Guide for Geologists and Engineers’, the book is the first of its kind, in concentrating on illustrations, and geological interpretations, of samples of rock and soil obtained from boreholes from throughout Hong Kong. A generally consistent format is used throughout with all of the main groups of rocks and many of the individual rock types present in Hong Kong being covered in terms of composition, distribution, geological setting, and site examples. Hydrothermal alteration, deformation, and weathering are also addressed, and there are sections on superficial deposits and karst. ‘
The book is clearly intended to be user-friendly and achieves a considerable success in this regard, being lavishly illustrated, and setting a very high standard in layout and visual impact. The text is comparatively brief, and partly in bullet point form where referring to Diagnostic Features, Key Points, Geological Importance and Engineering Significance. Although many of the illustrations are of common features, the book includes several features that have either not been illustrated previously, or have not been illustrated well, such as some of the structures. As many of the illustrations are of uncut rock core, a practical limitation, as emphasized by the author, is the distortion of the features illustrated. There are also problems on a few of the core photographs with uneven focus and illumination, but most are of good quality and they comprise a very useful resource overall. The illustrations of soil samples are generally of split samples, with little distortion other than that caused during sampling and some, for example those of laminated silt and clay (Section 16.6.3), are particularly fine.
While broadly consistent with current practice in soil and rock description, as contained in the industry standard of good practice - Geoguide 3, the book also reflects the author’s personal views on certain topics, which practitioners using the book should appreciate. Most notable, for example, are the descriptions and examples of weathered sedimentary and metamorphic rocks, and the items listed as being of ‘Engineering Significance’. The issue of weathering of sedimentary and metamorphic rocks is particularly problematic from the logging point of view, as recognized in Geoguide 3, and has to be dealt with on a case-by-case basis. The items of engineering significance are not definitive, but they were presumably not intended to be so, given that the author has described many in general terms, such as ‘may be’ or ‘can be’.
In conclusion, the range of lithologies and materials addressed is extensive, and the illustrations in particular comprise a very valuable resource for geologists and engineers working in Hong Kong. Although practitioners using the book should bear in mind that it presents the author’s personal view of interpretation of samples obtained in site investigation boreholes, the book is recommended to anyone interested in the geology of Hong Kong.
Book Review by Diamad Campbell
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The Geology of Site Investigation Boreholes from Hong Kong
Prof. Chris J N Fletcher