Subir K. Banerjee

2006 John Adam Fleming Medal Winner

University of Minnesota

Subir Kumar Banerjee was awarded the John Adam Fleming Medal at the AGU Fall Meeting honors ceremony, which was held on 13 December 2006, in San Francisco, Calif. The medal recognizes original research and technical leadership in geomagnetism, atmospheric electricity, aeronomy, space physics, and related sciences.


Since his arrival in the early 1960s—holding degrees in physics and exploration geophysics from Indian universities, and a Cambridge University (U.K.) Ph.D. in geophysics—Subir Banerjee has maintained an eminent position in the world community of rock magnetists and paleomagnetists. His unique role began with seminal works on the physics of magnetism in natural and synthetic materials, revealing an uncanny insight into the nature of magnetic materials. These early works were instrumental in creating a greater understanding and appreciation of the importance of rock magnetism to problems in paleomagnetism. Over subsequent decades Subir has instilled in all of us who research the records gleaned from rocks of Earth’s past magnetic field a fundamental awareness, namely, the need for any solid paleomagnetic conclusion to be anchored in a thorough understanding of the relevant rock magnetic conditions both at the time of and subsequent to the acquisition of remanence.

Subir’s prolific contributions on the fundamentals of magnetic remanence and its carriers in both sediments and igneous rocks—along with those many insights into the potential of rock magnetic investigation applied to a wide array of geophysical problems—are seen consistently throughout his career. With his students, Subir has researched a multitude of rock magnetic matters applicable to important problems in the Earth sciences: magnetic properties of seafloor basalts; paleofield strength on the lunar surface; fine-scale paleosecular variation and paleointensity from lake sediments; and grain-size magnetic thresholds in magnetite, to name a few. The focus he has brought to using variations in magnetic properties in both sediments and soils as proxies for paleoclimate and paleoenvironmental change is an enterprise now seen as a primary reward of rock magnetic study. Whereas many fundamental theoretical concepts of fine-particle magnetism originate in physics, it is the cutting-edge creativity and imagination of Subir and his students which has secured the bridge between rock magnetic study and Earth science as a whole.

What also makes Subir Banerjee such an exceptional researcher is not only his selfless dedication to the field, but also his steadfast belief in nurturing new ideas from younger members of the community; that is, his generous humanity. More than any other rock magnetist or paleomagnetist in the world, Subir Banerjee has fostered close interactions on an international scale. He has been a guiding light, the principal catalyst and spokesperson for a global community of cooperative research. It was Subir’s vision for a center fostering close ties and cross-fertilization of ideas that evolved into the U.S. National Science Foundation-supported Institute for Rock Magnetism (IRM) at the University of Minnesota, Minneapolis, where he has been director since its inception in 1990. This unique and highly successful facility houses some of the most sophisticated equipment yet developed for understanding the fine structure and properties of carriers of magnetic remanence. Several hundred scientists, emerging and senior, have seen residence at the IRM—truly the epicenter for state-of-the-art rock magnetic research.

At national and international meetings alike—including this very meeting of the American Geophysical Union—there are virtually no sessions involving magnetism and rocks that are not deeply influenced by the insights and the distinguished work of Subir K. Banerjee, this year’s recipient of the John Adam Fleming Medal.

—KENNETH A. HOFFMAN, California Polytechnic State University, San Luis Obispo


I am most grateful to AGU and the John A. Fleming Medal selection committee for choosing me as the medalist this year. It is not false politeness when I say that I am delighted, but also a bit surprised, at being selected to receive this medal, which honors a famous geomagnetist and is given for research in the magnetism of the whole gamut of solid Earth and its surrounding atmosphere.

Rock magnetism, my research area, concentrates its focus on the submicrometer scale, and my current research on magnetic biomineralization and environmental change is even at the scale of nanometers. What may not be self-evident is the essential role that rock and mineral magnetism plays in interpreting or reinterpreting paleogeomagnetic and paleoenvironmental records. However, as John A. Fleming himself pointed out in 1938, in addition to “ionospheric research to the solution of problems of the ephemeral variations of geomagnetism… [r]esearches on the magnetization of crustal rocks and anomalies of the Earth’s field produced by geological formations are potential sources of information but lightly drawn upon as yet.” (Thank you, Greg Good, for this quote.) By honoring me, therefore, the Union is recognizing the contributions not only of a single scientist but also all of us who work in fine particle magnetism of natural materials for both its fundamental aspects as well as its global applications.

As a research student at Cambridge University (U.K.), I was fortunate to be left alone to ‘sink or swim’ (an old Cambridge tradition) by my genuinely supportive supervisors, J. C. Belshé and the late Sir Edward Bullard. Frank Stacey and fellow graduate students Mike Fuller and Chris Harrison were, however, the day-in and day-out ‘research advisors’ who taught me my rock magnetism. During my postdoctoral years, first at Mullard Research Laboratories (Redhill, Surrey) and then at the University of Newcastle upon Tyne (U.K.), I discovered the allure and worth of low-temperature magnetic studies from Kurt Hoselitz and Ken Creer, my postdoctoral advisors, and Bill O’Reilly, with whom I formed a very productive partnership.

After my move to the United States, the late Allan Cox, my first true mentor, firmly redirected my vision of rock magnetism as an end, to a tool to solve larger-scale questions in geomagnetism, marine magnetism, and environmental charge records. The generosity of the U.S. National Science Foundation, the W. M. Keck Foundation, and the University of Minnesota, Twin Cities, have allowed me to realize my dream of founding the Institute for Rock Magnetism as a new international entity, ‘a college of scholars’ in rock magnetism. I have been helped in this by senior and junior colleagues, too many to be thanked individually. But I would single out for thanks a few, such as David Dunlop, Mike Fuller, Ron Merrill, and the late John Verhoogen from among my senior colleagues; postdoctoral colleagues Bob Butler, Ken Hoffman, Yohan Guyodo, and Thelma Berquó; and students Bruce Moskowitz, Steve Lund, John King, Christoph Geiss, Stefanie Brachfeld, and France Lagroix. The crucial support of my late parents, neither of whom could go to college, and the abiding love and patience exhibited by Karin (my ex-wife), Manju (my wife), and my three daughters, Sujata, Claire, and Rekha, have sustained me throughout, and I thank them from my heart.

—SUBIR K. BANERJEE, Institute for Rock Magnetism, and Department of Geology and Geophysics, University of Minnesota