Tuatara: Volume 24, Issue 2, August 1980
Book Review — New Zealand Adrift
Book Review
New Zealand Adrift
This latest book from Dr Graeme Stevens describes the past events which have shaped our country and influenced the survival of the plants and animals that we have today. There is, however, far more to the book than its title implies, for it does not restrict itself to New Zealand's geological history in terms of continental plate movements (like the ‘jostling of ice floes’). Rather it deftly unravels the history of the concept of plate tectonics and assembles the whole spectrum of evidence for drift on a world scale. Thus the breadth of topics covered include fossil magnetism, the structure of the oceanic ridges and trenches, earthquake distributions, the significance of sea mounts, ‘hotspots’ and ophiolites, as well as the theories of the origin of the solar system and the structure of the earth's core. In short, it is the layman's complete guide to geological processes with New Zealand as its central theme.
Continental drift has done wonders for the earth sciences. Like some other major scientific concepts that deal with ‘inconceivable’ events, a long time elapsed before the first coherent theory of continental movement was proposed by Alfred Wegener and a further 60 years was needed for it to reach a level of widespread acceptance. Now we find that it provides a great unifying theme on which the many diverse aspects of geology can be brought together. This exciting reorientation of thought has taken place during Dr Sevens' life and he has succeeded in conveying ‘something of this excitement’ in his book.
The book is aimed at ‘the needs of the general reader who is interested in how our earth has evolved’. Unnecessary jargon is avoided and essential technical terms are carefully defined. Literature references are not cited in the text, but there is a chapter by chapter list of ‘suggestions for further reading’ (a total of 359 including 105 concerned with the development of fauna and flora of New Zealand and the SW Pacific). Dr Stevens has, at the expense of repetition (even to reprinting an illustration twice), catered for the selective reader who wants to dip into the text at any point. Moreover, this policy extends also to the captions which are expanded explanations, allowing a great deal of the story to be gleaned from browsing through the pictures. Incidentally, the author's wife contributed the multitude of maps and diagrams, all redrawn from a variety of sources to provide a uniformity to the illustrations.
A large portion of the book is devoted to the development of New Zealand's biota, a discussion of its fossil record and the biogeography of the present-day fauna and flora. Although the page 92 conceptual framework is similar to that of Fleming (1979) reviewed elsewhere in this issue, the emphasis is different. As a biologist, I must say that I am not happy with the frequent and misleading use of the term ‘migration’ when palaeontologists discuss the subject of animal distributions. In this case we find ‘archaeic forms all needing continuous land for migration’, and ‘… ancestors of the wetas may well have migrated to New Zealand …’ and so on. The idea of wetas migrating is quite alien to what we know of these sedentary forest insects. Dr Stevens is, in fact, not referring to the specific, regular movement from breeding ground to feeding areas which occur in certain species of animals, but rather to the ecologically very different expansion and contraction of areas of distribution which occur in response to climate and other changes. The book also propagates another popular misconception which I cannot ignore, and that is the statement that ‘The reptiles … were the first animals to cut their ties to water and freely live and reproduce on land …’ when insects and other arthropods had taken this crucial step at least 100 million years previously.
I found the book both entertaining and informative on first reading and I am sure it will be used for reference for a long time to come. Graeme and Diane Stevens should be congratulated for the care with which they have presented this complex material so that it becomes available to the general reader.
G. W. Gibbs