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7: GEOPHYSICAL METHODS 153

Survey parameters such as line separation to have anything approaching the knowledge of
and line orientation, and all specifications re- a specific area and its geological problems that
lating to final reports and data displays, should is possessed by the members of an exploration
be decided between the project geologists team. Moreover, mining companies are often
and their geophysical adviser. More technical reluctant to provide contractors, who may next
questions, such as tolerances (navigational week be working for a competitor, with re-
and instrumental), instrument settings, flying cently acquired data. Since such information
heights in airborne surveys, and data control can be vital for good interpretation, contrac-
and reduction procedures, should be left to the tors’ reports are often, through no fault of their
geophysicist. Geologists who set specifications own, bland and superficial. They may only be
without this sort of help, perhaps relying on the worth having if the method being used is so
contractor’s advice and goodwill, are taking new or arcane that only the operating geophysi-
grave risks. Goodwill is usually abundant dur- cists actually understand it.
ing initial negotiations, and contractors will,
after all, only stay in business if they keep their
clients reasonably happy, but as deadlines draw 7.19 FURTHER READING
closer, and profit margins come to look tighter,
it becomes more and more tempting to rely on A number of textbooks cover the geophysical
the letter of the contract. techniques used in mineral exploration in some
Once a contract has been signed, the work detail. Of these, the most comprehensive is
has to be done. The day-to-day supervision can Applied Geophysics (Telford et al. 1990). A
usually be left to the geologists on the spot, briefer but still excellent coverage is provided
who will find a comprehensive and tightly by An Introduction to Geophysical Explora-
written contract invaluable. The greater the tion (Kearey et al. 2002), while Principles of
detail in which procedures are specified, the Applied Geophysics (Parasnis 1996) has a
easier it is to see if they are being followed strong mineral exploration bias, derived from
and to monitor actual progress. Safety and the the author’s own background in Scandinavia.
environment are becoming more important Interpretation Theory in Applied Geophysics
every year, and although the contract may (Grant & West 1965) is now hard to find but
(and should) specify that care for these are the also hard to beat as a summary of the theoret-
responsibility of the contractor, the company ical backgrounds to most geophysical methods.
commissioning the work will shoulder much Practical Geophysics II (van Blaricom 1993)
of the blame if things go wrong. Random and and Geophysics and Geochemistry at the
unannounced visits to a field crew, especially Millenium (Gubins 1997) provide a wealth
early in the morning (are they getting up at of largely North American case histories and
a reasonable hour, without hangovers, and do practical discussions but both tend to dis-
they have precise and sensible plans for the integrate if taken into the field. A third edition
day’s work?) or at the end of the day (have they of Practical Geophysics was produced in 1998,
worked a full day and are their field notes for on CD-ROM only. Practical aspects of small
that day clear and intelligible?), are likely to scale ground-based geophysical surveys and
be more useful than any number of formal some elementary interpretational rules are
meetings with the party chief. Evening visits discussed in Field Geophysics (Milsom 2002).
are particularly useful, revealing whether data Valuable case histories are to be found in
reductions and paperwork are keeping pace many journals, but especially in Geophysics
with the field operations and whether the and Exploration Geophysics, published by
evenings are being passed in an alcoholic haze. the Society of Exploration Geophysicists and
A geophysical contractor can reasonably be the Australian Society of Exploration Geo-
expected to acquire data competently, with due physicists respectively. The same two organ-
regard to safety and environmental protection, izations publish newsletter journals (The
reduce it correctly, and present results clearly. Leading Edge and Preview) that provide up-to-
Many also offer interpretations, but these may the-minute reviews and case histories. Three
be of limited value. Few contractors are likely Australian compilations, on orebodies at Elura