The great Canadian scientist Norman L. Bowen is seen today as the foremost founder of experimental petrology in the twentieth century. His work was revolutionary in method, brilliant in design, and fluent in the telling. Controversy raged about him, stimulating the rhetorical juices that produced memorable ripostes.
Bowen stands apart from all others in his impact on the study of igneous rocks. For example, his 1915 determination of plagioclase partitioning in diopside-saturated liquids has not been improved by any analytical method since, and is not likely to be. His 1928 book, The Evolution of Igneous Rocks, which was reviewed even in The Times Literary Supplement, served as the fundamental text in igneous petrology for half a century; it is still indispensable. His 1932 work with Schairer on the melting of fayalite showed the coexistence in a silicate melt of Fe0, Fe2+ and Fe3+, and laid the groundwork for a seminal analysis by Lindsley of olivine and pyroxene melting. All these and many more virtues are described in this welcome monograph by Davis Young.
This book is a stunning exercise in scientific biography. Although it is focused on Bowen's theme of crystallization-differentiation, what most of us would today call fractional crystallization, it spans the man's life work except for the metamorphic studies. Although biographical, it also carefully and skillfully reveals the science in the context of the great debates of the day. And although scientifically rewarding, it also contains biographical sketches and anecdotes about all the major players who were affected by Bowen's theories and writings.
Especially to an igneous zealot, this book is an engaging detective story. The violent disputes with Fenner over the interpretation of Harker diagrams, and with Read and Reynolds over the origin of granite, are brought vigorously to life. The elegance of the experiments and the writings, contrasted with the fury of rebuttal by the paradigm guards of the day, cannot fail to be gripping. And of course, this account is to a large degree a history of the Geophysical Laboratory in the first half of the century, along with major visits to the geological halls of Chicago, Princeton and Yale, and with Harker to the outcrops of Mull.
The wars between Bowen and C. N. Fenner stand out among the uproars of early twentieth century science. The first battle was Fenner's rejection of Bowen's use of phase diagrams to interpret rocks. Fenner used variation diagrams to show that their linear arrays were inconsistent with expectations from fractional crystallization; instead, he voted for gaseous transfer. The second battle was over whether the residua of basaltic crystallization were enriched in iron or silica, the trends that are now sometimes called the Fenner and Bowen trends. The conflicts were acrimonious and they involved formal letters, at times sent through the Director of the Geophysical Laboratory within the same building. In his 1928 book, Bowen demolished the argument from variation diagrams by showing that Fenner had mixed crystalline rocks with glasses; by using only the glassy or aphanitic compositions, he could show trends that were indeed what one expected from fractional crystallization. Young devotes two lively and refreshing chapters to these arguments.
The other major war of Bowen's career was, of course, the granite controversy, and this too is given a thorough, clear and enlightened treatment. In this, the triumph came late in life with his and Tuttle's low-temperature melting of granite with water, but the polemics on the way are well remembered and given good treatment here.
It is perhaps surprising to the modern reader that there should have been such resistance to Bowen's scientific findings and their application. But resistance stimulates new approaches to old problems, and without the fanciful ideas of the diffusionists, we might not have had the brilliantly pace-setting 1921 paper on diffusion in silicate melts. This work is one of my favourites, not least for its helpful language about the error function (erfc), to wit: do not be alarmed by that erfc, it is just the probability integral and you look it up in tables.
Professor Davis A. Young teaches geology at Calvin College in Michigan. To our great good fortune, he took A. F. Buddington's petrology course at Princeton, and was bitten by the bug. He was then infected further with an M.S. at Penn State and a Ph.D. at Brown. As a result, he writes felicitously not just about Bowen, but also about Daly, Goldsmith, Grout, Harker, Iddings, Morey, Hess, Wager and Yoder, and he also mentions such of our contemporaries as Gittins, Ghiorso, Oxburgh, Presnall and Sparks.
The author updates all of Bowen's enterprises related to crystallization-differentiation in a concluding chapter with copious references to recent work. His use of the word evolution in the subtitle is a felicitous reference to Bowen's own title of 1928, and he concludes this book with a section on the evolution metaphor in relation to Charles Darwin. He justly concludes that Bowen had no intention of comparing himself to Darwin, but followed a path that goes back at least to Harker. But I especially liked his closing sentence: ‘Just as modern biology would be unthinkable without the overarching genius of Darwin, modern igneous petrology would be unthinkable without the overarching genius of Norman Levi Bowen.’
Every student of petrology will want to read this book; it will teach them scholarship. Many geology students may find it intriguing enough to encourage a study of petrology. If they do, the book will be a fine narrative introduction to the subject. It should hook plenty of readers into our science. I am proud that MSA has published it, and for a price of only a few beers. Save today and buy tomorrow. Give it to a kid to read.