Download Book Review of "The Earth`s Mantle – Composition, Structure and

Book Review of "The Earth’s Mantle – Composition, Structure and Evolution" edited by
Ian Jackson (Cambridge University Press, 1998)
by Thorne Lay
Professor A. E. (“Ted”) Ringwood (1930-1993) made numerous seminal
contributions to our understanding of the chemical composition, origin and evolution of
the Earth and Moon, and the ideal tribute would capture some flavor of his rare skills for
experimentation, synthesis and inference. This volume comes admirably close to the
ideal, bringing together synoptic review papers from Ringwood’s colleagues in the
Research School of Earth Sciences of Australia National University (ANU) as well as
their collaborators, in a highly accessible overview of the Earth’s mantle. The most
remarkable achievement of the volume is the sustained pedagogic tone of the separate
sections, clearly the result of a masterful editorial input by Ian Jackson and his editorial
advisory board. The result is a modern, expansive and authoritative presentation of great
value for beginning or advanced researchers interested in the deep Earth. The book also
provides a fascinating window into a “world view” rather forcefully advocated by one of
the world’s leading Earth science research institutions.
The book is organized in three parts, with a total of 11 papers. The first part
addresses Accretion and Differentiation of the Earth in three chapters that emphasize
geochemical evidence for bulk chemistry of the Earth, the time scale of accretion and
core formation, evolution of the crust, and origin of the atmosphere. The primary
arguments underlying prevailing paradigms for notions of Earth composition and early
history are thoroughly elaborated, with a presentation that is quite balanced and
penetrating, but which proves easy to follow even for the non-expert. Indeed, all
geophysicists would enjoy and benefit from reading this part of the book, as it makes the
geochemical observations and arguments more accessible than most of the associated
literature. It is particularly fascinating to harken back to Ringwood’s two famous books
Composition and Petrology of the Earth’s Mantle (1975) and Origin of the Earth and
Moon (1979) to attain a perspective of what advances in understanding and new lines of
evidence have emerged over the past quarter century. This exercise also imparts a keen
appreciation for Ringwood’s early contributions and how many of his ideas have
endured.
The second part of the book is Dynamics and Evolution of the Earth’s Mantle,
with chapters addressing laboratory experiments on boundary layer flows, a general
discussion of mantle convection and evolution, chemistry of the mantle inferred from
plumes and associated melting processes, and a review of the pyrolite model and the
genesis of basalts (perhaps Ringwood’s area of greatest contribution). This section lays
out many of the key ANU contributions to ideas about mantle dynamics, with particularly
thorough discussion of the dynamics and chemistry of mantle plumes from a variety of
perspectives. Attention is also paid to downwellings, and the relative roles of internal
heating versus boundary layer instabilities. A persistent theme of the entire volume
emerges most clearly here; the notion of a unified model of whole mantle convection,
albeit one with entrained chemical heterogeneities. It is likely that these chapters will
also stimulate the most argument, and the referencing is rather ANU-centric for such
sweeping topics, but this has the merit of defining the institutional perspectives with great
clarity. Some of the controversial nature of the topics is lost, but instructors can readily
complement this volume with other reviews to provide students with the full range of
ideas about mantle dynamics and evolution.
The third part of the book emphasizes the Structure and Mechanical Behaviour of
the Modern Mantle. One chapter summarizes seismological models of the mantle, albeit
from a rather narrow perspective of studies in some way connected to ANU. This
suffices to touch upon many aspects of seismological contributions to our knowledge of
the mantle’s structure, but falls short of the pedagogic thrust of earlier chapters. The next
chapter provides a satisfying overview of interpretation of seismic models in terms of
experimental and petrological constraints on composition and temperature. The
treatment of deep mantle chemistry is particularly interesting, as most available surveys
emphasize upper mantle conditions. Glacial rebound is exploited to place constraints on
mantle viscosity in the next paper, with both theory and observation being addressed.
The final chapter explores the topics of mantle rheology and phase transitions by
summarizing results of laboratory studies.
The composite portrayal of the mantle provided by The Earth’s Mantle is rich and
diverse, and of broad interest to all students of the deep interior. While not all
perspectives are represented, the complexity and non-uniqueness of the inferential
process is well presented, and there is no danger of completing the book and feeling that
all questions about the mantle have been resolved. Yet there is clearly a sense of
tremendous progress in deep Earth research. The interdisciplinary nature of the effort to
understand the Earth is aptly conveyed, and the great advances that have been made are
established as the results of a broadly based effort spanning many disciplines and analytic
procedures. There is also the underlying attribute of creativity and intellectual integration
that makes the achievements of the Earth science community and its luminaries such as
Ted Ringwood so impressive. While new discoveries and ideas about the deep mantle
continue to emerge at a feverish pace, this tribute to Ringwood will have lasting value as
a synoptic overview of mantle processes for long to come.
Thorne Lay is Professor of Earth Sciences at the University of California, Santa
Cruz