9302932.891 Westbroek, Peter LIFE AS A GEOLOGICAL FORCE: The Gaia movement continues as Westbroek (Prof. Geology and Biochemistry, University of Leiden, Netherlands) makes a convincing case for integrating the biological and geological sciences, acknowledging life's historical and potential role in the evolution of Earth. A unique, complex and constantly changing interplay between biological and geological forces is taking place on this planet, claims Westbroek, in which living organisms affect the fate of the earth as profoundly as the earth's physical transformations affect life. Hardly front-page news in this era of ecosystems and increasingly 'unified' scientific vantage points, but a supposition largely ignored until recently in an atmosphere of extreme scientific specialization. The effects of living organisms on such geological phenomena as plate tectonics and climate are profound, as are the cultural extensions of our own biological existence-- bulldozers, pollution, conservation and so on. In tracing the development of such cause-effect relationships, Westbroek proves both informative and entertaining, particularly when describing how, through trial and error over the centuries, men altered the geological history of Holland's landscape; how marram grass participates in the 'rock cycle'; and how a sealed, impressively balanced biosphere in the author's study compares to the planet Earth spinning in its cocoon-like atmosphere. The authors' closing remarks on man's potential to turn the entire earth into a cultural domain, 'a kind of park, a giant laboratory, or a great work of art'--in other words, an enormous Holland--may give some readers pause, but in general this offers a cornucopia of fascinating details.