160 BOOK REVIEWS

Geology of the country around Worcester (sheet memoir199 (England and Wales)), W. J. Barclay, K. Ambrose, R. A.Chadwick and T. C. Pharaoh, 1997, HMSO, London, xii +156 pp. ISBN a II 884512 8 (PB), £55.00.

This memoir describes the geology of the northern MalvernHills and part of the Worcester Basin, with solid rocksvarying in age from late Precambrian to Jurassic. Inside thefront cover, these formations which make up the geologicalsuccession are listed in a useful summary table. The districtcan be divided into three main outcrops: the Palaeozoicrocks of the Welsh Borderland to the west; the smallPrecambrian inlier of the Malvern Hills; and to the east ofthis the Permo-Triassic fill of the Worcester Basin. Theintroduction is clear and well presented with a briefsummary of the geological history of the area covered bythe memoir.

The chapter on the Precambrian is very detailed and thematerial is covered too briefly with often highly technicaljargon left unexplained in the text. However, the openingpart of the chapter is clear with a useful map of the inlierand a list of quarries in the area. The details of the rocks'geochemistry is poorly explained and unnecessarily com­plex, though the diagrams are clear and well drawn. Thereis a brief chapter on the Cambrian and Ordovician with aclear and useful map of the complex geology of theCowleigh Park area.

The Silurian rocks of the Malvern inlier are covered ingreat detail with a good introduction and two good plates ofthe fossils found in these sediments, which show a greatdeal of variation. The much more widespread Devoniansediments are covered in a short chapter as these rocks yieldfar less material.

The Permian and Triassic mudstones and sandstones ofthe Worcester Basin are covered at length with detailsmainly obtained from deep boreholes and geophysical logs.There are extensive lists of the fossils found in theseborings, along with clear, well presented photographs ofsome mudstone layers. Considering the small outcrop ofLiassic rocks in the east of the area and the very limitedoutcrop of the Inferior Oolite in the southeast on the top ofBredon Hill they are covered at some length, with details ofthe depositional history, the geophysical log characteristics,and stratigraphy.

The mainly fluvial deposits of the Quaternary are dealt

with at some length along with glacigenic and lacustrinedeposits. A clear table shows how all these deposits relate tothe stages of the British Quaternary and their tentativecorrelation with the Oxygen isotope stages.

The chapter which details the area's structure divides itinto three: the Malvern axis, which is the result of Variscanmovements; the rocks to the west of this axis; and those tothe east of it. In the description of the Lower Palaeozoicrocks the structures are grouped according to theirpredominant trend and not necessarily their age offormation or reactivation. The structure of the Worcesterbasin is illustrated by very good seismic sections, contourplots and a true-scale 3D view of the pre-Permian basement.The final section of the chapter is on the results of studyingthe gravity and magnetic data for the area. The shaded reliefplot of gravity illuminated from the west is unclear due tothe large drop in the anomaly just to the east of the Malvernaxis, while the modelled profile of the observedaeromagnetic and Bouguer gravity is very clearly presentedin such a way that anyone with the right software couldreproduce the model.

The economic geology chapter starts with a section onthe water resources of the area and has a table of chemicalanalyses of the different groundwaters in the district.However, Malvern Water only has a brief mention despitebeing worth over £II million a year, and no chemicalanalysis is given. This is followed by a brief description ofthe area's mineral resources and geological risk factors thatshould be considered in planning future development of thedistrict.

Overall the figure and photographic plates are clear andwell presented. Apart from the chapter on the Precambrianbeing too brief and technical, there is about the right amountof text for the material covered. The need for technicaljargon could have been partly resolved by including aglossary of these terms and an explanation of some of thekey ideas that need to be grasped in order to understand thecomplex history of the Precambrian rocks. After all, theMalvern hills are the most studied and visited geologicalfeature within the area. However, this memoir will be thekey reference for anyone wishing to study the geology ofthe Malverns and the Worcester Basin.

DAVID NOWELL2 Tudor Road, New Barnet, Herts