JOURNAL OF PETROLOGY
VOLUME 40
NUMBER 10
PAGES 1577–1578
1999
Book Review
N. L. Bowen and Crystallization–
Differentiation: The Evolution of a Theory by
Davis A. Young. Mineralogical Society of
America, Washington, DC, 1998.
Mineralogical Society of America
Monograph No. 4. 276 pp. ISBN 0939950472.
US$16 (US$12 to MSA members).
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 diopsidesaturated 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
 Oxford University Press 1999
JOURNAL OF PETROLOGY
VOLUME 40
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.’
NUMBER 10
OCTOBER 1999
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.
S. A. Morse
University of Massachusetts
1578