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potential for further neotectonic studies virtually unlimited.

The Lesser Antilles is a belt of active volcanoes punctuating a chain of islands above a subduction complex. Geoffrey Wadge concentrates first on the overall structure of the arc, discussing in detail the geophysical data from the chain. The 50 Ma history of the arc is assembled and the petrochemistry of the volcanic rocks discussed. In conclusion, the volcanic activity of 14 recently active centres and their hazards are outlined; high risk areas can be defined and protected. Robert Speed investigates the development of Barbados and the Lesser Antilles Forearc. Whereas Barbados is part of an accretionary prism. the Lesser Antilles form a curving arc platform with a forearc basin to the west, the Tobego Trough, and the Grenada Basin to the east. Barbados itself consists of a varied package of rocks including a basal complex, prism cover, allochthonous oceanic material together with diapiric melanges, covered by a Pleistocene limestone cap of reef material.

Trevor Jackson and Stephen Donovan, the two editors, together tackle Tobago. This small but signifi- cant part of the south-east Caribbean may have developed ;is ;in allochthonous tcrrane forming the easternmost chunk of the Caribbean Mountain System. There is much of interest here: Mesozoic igneous and metamorphic rocks associated with two phases of arc development are capped by the Plio-Pleistocene Rockly Bay Formation, locally packed with fossils. Trinidad. by virtue of its site a t the interface between the south-east corner of the Cnribbean plate and the northeast margin of South America. although relatively small, is o f considerable geological significance. Stephen Ihnovan describes in detail the stratigraphy of the Northern Range and the Trinidiid Province. comprising the Northern Basin, Central Range, Southern Basin and Southern Range. Four main stages are tracked, from a mid Jurassic to late Creraceous rift and passive margin phase, through latest Cretaceous to mid-Early Miocene episodic transpression and mid-Early Miocene to late mid-Miocene extension and finally late mid-Miocene to present transpression.

IMAGE IN1’ERPRETATION IN GEOLOGY, 2nd edn, by S. A. Dmry. Chapman & Hall, London, 1993. No. of pages: 283. Price: f24.95 (paperback). ISBN 0 412 48880 9.

‘Before plate tectonics there was continental drift: before remote sensing there was aerial photography’.

And although the impact of remote sensing may not be so dramatic, the way we can now view and interpret images of the earth is revolutionary and perhaps invites a wider consideration than it has had to date. Drury’s book bolsters the importance of remote sensing and image interpretation in geology and builds upon the success of the 1987 first edition.

There are numerous definitions of remote sensing in general textbooks, all trying to relate the same thing.

Stephen Donovan provides an extensive review of the geology of northern South America, essentially docu- menting the southern Caribbean plate boundary zone in this region. The history of the region is charted from its Archean and Proterozoic basement associated with the Guyanan and Brazilian shields through patches of Palaeozoic to the more coherent Mesozoic and Cenozoic successions of the regon. This is a useful synthesis of a less well-known region, including a series of Dewey- grams illustrating the complex Cenozoic tectonic history of northern South America. The Netherlands and Venezuelan Antilles are described by Trevor Jackson and Ted Robinson. These archipelagos are part of the southern Caribbean island chain with a geographical history ranging from the early Cretaceous to the Holocene. Upper Cretaceous lower Tertiary volcanic and sedimentary sequences were intruded by a variety of dykes, sills and plutons; these complexes are uncom- forrnably overlain by Tertiary-Holocene sedimentary sequences commonly with rich coral-dominated faunas.

Burke Burkart wraps up the book with the geology of North Central America, where the Cocos, Caribbean and North American plates interface. The main geolog- ical provinces are discussed and illustrated. Proterozoic and mid-Palaeozoic basement complexes. Carboniferous and Permian basins. Cretaceous arcs, carbonates and ophiolites together with Tertiary volcanics combine to illustrate the long complex history of this region on the western margin of the Caribbean. Finally, the index is restricted to mainly geographical and matigraphic tcrms but is, nevertheless, both comprehensive and useful.

There is massive diversity of information in this book, essential for any researcher interested in the Greater Caribbean region; moreover, there are many possible modern analogues for palaeotectonic models and a diversity of well-documented case histories for lecture material. The hook has been cheaply produced for ;t

wide market at almost A4 format. Nevertheless the typeface and illustrations, hidden behind a striking cover, are crisp and clear. The text is thoroughly recommended for both content and presentation.

DAVID A. 1‘. HARPER

Drury describes remote sensing as ‘the capture of infor- mation about the earth’s properties in the nearly continu- ous two dimensional fashion that is characteristic of images’. The provision of useful, short and meaningful definitions seems to be a (realistic?) priority of all remote sensing texts. They rarely succeed to encapsulate its mean- ing in one sentence and Drury’s attempt is no exception. However, it is in the ensuing delivery of competent and widely acccssible text, punctuated with a gallery of stimu- lating imagery, that he succeeds.

His 20 years of experience in developing and using multimedia teaching techniques at the Open University has not been lost in the design and construction of this book. Its clear explanatory text, accompanied by numer- ous illuminating panchromatic and colour images, dia- grams and graphs, together with a further reading list to

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each chapter and a glossary, makes for comfortable read- ing. Any reader of remote sensing texts will know of the value of the latter two features. Firstly, many authors quote copious references that can only be obtained by costly inter-library loan. Here, many of the references will be found in a typical university library. Secondly, as with any discipline which has had its origin in the development of space science, the reader must possess a prodigious knowledge of acronymic jargon and so a glossary is a vital appendage.

The two most important points about this book are that it is up to date in a field which is undergoing rapid development and that it is one of just four textbooks that concentrate on geological remote sensing. Thus in this field of sparse literature the reader will be well served by this book.

The mechanics of remote sensing and image processing are dealt with in Chapters 3 and 5. The former outlines how data are collected and ranges from the earliest means of remote sensing, aerial photography, to high tech- nology imaging spectrometers and the numerous satellite platforms that carry these electronic boxes. The latter introduces the process of digital image processing, which is used to enhance the raw data. Here, the full value of the raster structure (the grid of pixels which represents the varying energy levels reflected from the earth’s surface) is revealed. Computer processing is enabled by the simple regular nature of the raster structure, although it must be remembered that it does not accurately represent the real world of complex shapes. Numerous photographs of images reveal how processing can enhance imagery, im- proving geological discrimination. (Note here the tech- nical distinction between the terms image and photograph. A photograph is a chemical emulsion on paper; an image is a computer screen with an underlying pixelated database that can be computer manipulated.)

The remainder of the text reveals how imagery can be used in geological studies. Chapter 4 concentrates largely on panchromatic photography referenced by numerous stereopairs. Photogrammetric aspects are not covered, except for stereometry, which is detailed in an appendix. The justification for this is the lack of space, and an unusual but laudable statement, in the preface, which explains that as there has not been significant advance- ment in this field since the 1960s readers should refer to the older texts. It is rare to see an admission such as this, especially in a high-tech work. Longer wavelength sens- ing, in the thermal and microwave segments of the spec- trum, are covered in Chapters 6 and 7. This imagery can be very useful to geological studies, but the dearth of geologists well versed in its application restricts its full development. Again, good use is made of graphs and imagery to explain these more esoteric forms. Chapters 8 and 9 are new to the second edition. Chapter 8 introduces the role of non-image raster data and GIS in geology. There is an increasing store of such data which spans fields such as geophysics, geochemistry and mineral ex- ploration. The possible manipulation of these data by spatial databases and their transformation into visually digestible imagery is certainly appealing, yet costly in time and money. This probably accounts for the rather slow take-up of this methodology. Drury makes two valid

suggestions here that are worth relating. Firstly, he calls for ingenuity, particularly in the development of appli- cations using non-image raster data, adding that recasting such data can reveal important and hitherto unseen infor- mation. Secondly, he suggests that by establishing a global ethos for employing spatial databases across the spectrum of users, the development of techniques and applications will be lubricated.

The book is essentially about the value and application of satellite imagery in geology, although Chapter 8 launches into the growing field of non-image raster data. The nine chapters describe and develop three broad areas of interest. Chapters 1 and 2 elaborate the principles of remote sensing; Chapters 3 and 5 cover the mechanics; and the remainder deal with the principles and geological applications of specific types of imagery. Drury admits to just one chapter being devoted to the applications of geological remote sensing (Chapter 9), but this undersells the book because at least five of the chapters fall into this category and underline the significance of this book to geologists. The chapter on photogeology (Chapter 4) sits curiously and uncomfortably between chapters that deal with the mechanics of remote sensing and image in- terpretation (collection and manipulation of data). It would have been better placed later in the book and included as an application, as that is what it is.

The first chapter describes how energy mainly from the sun (except for thermal and microwave remote sensing) finds its way through the atmosphere to the surface only to be reflected or absorbed to varying degrees by a range of earth materials (rocks, soil, vegetation, etc.). A variety of airborne (aeroplanes) or orbiting platforms (satellites) record the levels of reflected energy in specific wavelength bands with a host of sensors (cameras to radiometers). Thus the term remote sensing is explained. Chapter 2 on human vision is not the short of chapter that one would instinctively expect to find in a geological text. Geologists rarely use senses other than sight and thus a foray into the field of psychophysiology is justified because of the need t o create images that are attuned to the characteristics of human vision. This chapter introduces important points in the field of remote sensing and image interpretation. Successful image analysis depends on two things the ability to relate the level of spectral response, or processed colour, to a particular material and, secondly, the ca- pacity to extract meaningful information from a collec- tion of coloured pixels. The latter requires some understanding of how the virtual cortex discriminates between colours, lines and shapes. The significance is underlined by the fact that human visual perception is limited to the determination of just 2G30 grey tones, while the limit on colour discrimination is apparently some seven million hues. Thus it seems that colour imag- ery is not a simple luxury. For the geologist, this may not be the most appealing chapter to read, but it is probably the most important!

The final chapter reviews the range of geological appli- cations of image data adding another definition of remote sensing ‘as a kit of tools that a geologist can deploy as and where necessary’. Seventy-one references are cited as fur- ther reading and cover a range of fields from geological mapping to exploration and geochemical hazards.

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As a specialist text one might imagine the readership of this book to be somewhat limited. But this should not be the case. Potential readers should include all research and exploration geologists whatever their locational per- suasion (field or laboratory). There will be something in this book they could use. Undergraduates following specialist courses in remote sensing or specialist field courses will also find much of value. It should be on the general reading list for all third year honours students in geology, who at the very least should understand some of the potential, and pitfalls, of imagery used in geological studies. And, finally. for the amateur, this work is likely to appear somewhat daunting, although there is a lot of stimulating information that could be gleaned, not least ofwhich from the many photographs of images. However they, and perhaps, years 1 and 2 geology undergraduates, should not be deterred. and would be well advised to refer to Drury's ' A Guide 1 0 Remote Sensing', published in 1990, for a stimulating introduction.

Many texts are by nature historical in their accent, outlining what has been achieved to date and by whom,

this edition does this and more its a window, or perhaps a computer screen, to the future -if we choose to use it .

GERALD R. LWAS

REFERENCES

Drury, S. A. 1990. A Guide to Rernore Sensing. Interpreting Imuges q/ the Eurrh. Oxford Science Publications, Oxford.

Lawrance, C. J., Byard, R. J. and haven, P. J. (1993). 7erruin Evaluation Manual. State of the Art Review No. 7. HMSO, London.

Legg, C. A. 1992. Remote Sensing and Geogruphic Informulion Systenis. Geological Mapping. Mineral Exploration and Mining. Ellis Horwood.

Sabins, F. F. 1986. Remote Sensing: Principles undlnterpretation, 2nd edn. Freeman, San Francisco.

Siegal, R. S. and Gillespie (4s) 1980. Remote Sensing in Geology. Wilcy, Chichester.

HEY'S MINERAL INIIEX, MINERAL SPECIES, VARIETIES AND SYNONYMS, 3rd edn, by A. M. Clark. Chapman & Hall, London, 1993. No. of pages: 852. Price: f50.00. ISBN 0 412 399 504.

This is a new edition of Hey's The Cheniical Index of Minerals which has become a standard reference work throughout the world. This, the third edition, has been completely revised by Dr Andrew Clark of the Natural fIistory Museum, London. It consists of an alphabetical list of mineral names including species, varieties, syn- onyms and. in some cases. different spellings and in- correct spellings of the names. The species are distinguished in the list by being printed in bold type.

The chemical classification occupies only 65 pages of the total book and I shall comment on it first. Only the species are listed and there are nearly 3500 names. They are classified in the same way as in previous editions, but have had to be re-numbered to accommodate the hun- dreds of new species which have been reported since the publication of the 1974 edition. The species are divided into 32 groups, the smallest being the thiocyanates, of which there are only two. The largest group consists of the silicates not containing aluminium, of which there are 374. Most petrologists and mineralogists would probably have guessed that silicates containing aluminium would have been more numerous.

The major part of this large book is the alphabetical listing of the mineral names. Reference is made to the original use of the name and whether it is a species, a variety name or a synonym. In the case of a species, each mineral name is followed by its chemical formula and a number which refers to its chemical classification. A refer- ence to the original description and the type locality are included, as is the origin of the mineral name. The crystal system, unit cell dimensions and formula unit contents are

given and a file number for those minerals whose unit cell dimensions were obtained from the powder diffraction file. The entry for a species may finish with the names of varieties and synonyms.

Of necessity, a lot of space is occupied by variety names, different spellings, etc.. and there must be between 20000 and 30 000 entries. In a work of this magnitude and complexity there are bound to be some errors or omis- sions, and Dr. Clark asks readers to notify him of these and updated information prior to the data being provided in disk form.

There may be some disagreement as to what constitutes a species. but I have assumed that only end-members of a solid-solution series are species; thus hypersthene is not a species, however augite is and it has 12 synonyms and 15 variety names. Of the plagioclase series only bytownite is a species, in addition to albite and anorthite. In the entry for bytownite it is stated that the analysis by Tennant (1838) was probably on a mixture. Could it not equally well be the result of a poor analytical technique judged by modern standards?

This is not a suitable volume for fireside reading, mainly because it is too heavy, but many of the entries are extremely interesting for anyone interested in natural his- tory. One name I just happened to notice was mussolinite as 'A variety of talc from Sardinia, Italy. Presumably named after Benito Mussolini'. Fortunately, no-one named a mineral after Adolf Hitler.

Dr. Clark is to becongratulated on thismost impressive piece of work and the publishers should also be congratu- lated in having sufficient faith in this book to price it a t a level which permits the individual to buy it and not have to rely on the library copy. It should be available in all geology departments throughout the world.

W. S. MACKENZE