b'Don Emersons best of Exploration GeophysicsFeatureDon Emersons best of Exploration GeophysicsOn the other hand, the methodological /computational side of magnetics is in a very healthy state. Indeed, magnetics seems to be suffering from computobabble; it is in danger of becoming a mausoleum of irrelevant methodologies. Instead of being concerned with eliciting meaningful geological information from field and laboratory magnetic measurements, many publishing geophysicists appear to devote themselves to methods and variations on computational themes rather than interpretation improvements. I wish to make it quite clear that I am not advocating censorship or discouragement of this type of study. Scientists, quite rightly, follow their own inclinations in their work and researches. Furthermore, without some of the brilliant recent Don Emersonmethodological/computational advances, magnetics would Editor Exploration Geophysics 1984-93be a very backward and limited discipline. What I do advocate systemsnsw@gmail.com is that geophysicists with a data interpretation bent be actively encouraged to publish and discuss their work. After all, that is what applied geophysics is all about - the solution of geological Memories. While admiring the detail of pixelated perfection inproblems in understandable and meaningful terms. There is a some recent magnetic images, I recalled some comments I madegreat need to remedy the imbalance between interpretation at the Applied Magnetic Interpretation Symposium held 42 yearsand computation. The imbalance can be demonstrated by ago at the University of Sydney. I convened this meeting, whichconsidering 136 hard rock magnetic papers published in was well attended by over 100 geophysicists and geoscientists. Geophysics (a journal of very high standard) between 1962-1977.The Proceedings were published in 1979 in the ASEG Bulletin 10Twenty seven per cent of the papers were of the fundamental (1) p 3-139. This is the first part of my introductory comments: theoretical type - they were without exception, excellent and worthwhile. Also, twenty seven per cent comprised trivial, The subject of applied magnetics in hard rock environments"me-too, elegant, mathematical variations on computational has interested me for many years. Magnetic data are cheapor methodological themes. Next, twenty six per cent consisted and are employed by geophysicists and geologists in a varietyof good interpretation and case history papers tied into the of investigations including ore search, regional studies andgeology. Then thirteen per cent comprised miscellaneous lithological/structural elucidation. Most earth scientists, even(instrumental etc.) papers. Finally, the very important academics, are familiar with magnetics. On reviewing thepetrophysical topics (susceptibility and remanence) accounted literature and perusing open file exploration company reports,for only seven per cent. So it can be seen clearly that only one one cannot help being struck by the imbalance betweenthird of the papers were concerned directly with the true task methodology and interpretation. of magnetics - solving or clarifying geological problems. I say Let us look at interpretation; it is indeed a sad situation, acategorically that such a proportion is far too low, and this is the barren field. Often data are simply eyeballed into a qualitativereason for the Applied Magnetics Interpretation Symposium.interpretation. Quantitative interpretations where attempted,How things have changed with the substantial progress since often owe more to geometry than geology. They have an airthen! Australian geophysicists feature prominently in the of geological unreality about them as there is commonly littlevanguard of excellent professionals who have advanced the in the way of auxiliary control, corroboration and checking.practice of magnetics in data acquisition, presentation, and It is unfortunate for geophysics in general and magneticsinterpretation. Outstanding work has been carried out over the in particular that hypotheses are rarely tested. This leads toyears by magnetic laboratories and groups in CSIRO, universities, some very brave predictions or to inferences so qualified asgovernment agencies, AMIRA projects, and companies.to be useless or tautological. My comments, of course, do notThe insightful work carried out by the CSIRO rock magnetisation apply to all interpretations. Examples of worthwhile publishedgroup is especially significant. From their series of publications and unpublished interpretations are numerous, but overallone, to me, is particularly noteworthy, namely: Dave Clarks they are in the minority. Let us consider what two eminentcontribution to meaningful interpretation of the magnetic mathematical geophysicists have said about interpretation: petrology of igneous intrusions. A masterly overview (David "Although aeromagnetic data have been collectedA. Clark, 1999, Magnetic petrology of igneous intrusions: all over the world for the past 30 years at a totalimplications for exploration and magnetic interpretation, astronomical cost, it is safe to say that practicallyExploration Geophysics, 30:1-2, 5-26, DOI: 10.1071/EG999005). nothing is known of the physical characteristics ofThis is my BEST PAPER choice; it is a CLASSIC PAPER.the rocks that produce the magnetic anomaly. TheI commend it as refreshing re-reading to all interested in unpredictability of observed magnetic field over rocksmagnetic anomaly interpretation.where geology is known reinforces this observation. In our opinion, one of the most significant studies that ought to be made in the immediate future is theReferencesrelationship between mineralogy and petrology, rock magnetism and aeromagnetic anomalies. (I. Zietz &David A. Clark 1999. Magnetic petrology of igneous intrusions: B.K. Bhattacharyya, Rev. Geophys. Space Phys., 13 (3),implications for exploration and magnetic interpretation, p178-9, 1975). Exploration Geophysics, 30:1-2, 5-26, DOI: 10.1071/EG99900543 PREVIEW APRIL 2020'