The Camera and the Interrogator

Speak to exploration geologists and you will find two views about what a geologist should do when observing outcrop or drill core in the field.  Some seek to be unbiased objective recorders of what they see.  Others constantly theorise about what they might expect, construct many possible scenarios, and ask questions of the rocks to help choose between them. The competing metaphors are of the geologist-as-camera, and geologist-as-interrogator.

Geologist as camera – 1

I arrive at the exploration site to find a team of three young geologists engaged in making a geological map of their property. Using GPS, they walk predetermined traverses spaced 400m apart. They each aim to average 8km in a day and, between them, by taking alternate lines, they will cover a huge swathe of country before their next field break[1] . Observations on each geological feature identified along the line of march are logged into a Tuff book Laptop computer by going through a series of pull-down menus and clicking the boxes on pre-determined questions. The geologists have only the most imprecise ideas about the geology of the property they are mapping. Two of them have never thought much about this: the brightest of the three specifically rejects the notion of understanding her observations: she is the unprejudiced, objective observer  – confirmation bias is not for her. Eventually this data will be computer-plotted on a map as a linear sequence of point observations.  Another more senior geologist[2] will eventually produce a geological map by joining up the dots. 

Is this the future of Geological mapping in the 21st Century?GEOLOGISTS WORKED OUTDOORS

Geologist as Camera – 2

I travel to an exploration site on the other side of the country. Here, a much larger company is drilling out a substantial metal deposit. Four diamond drill rigs are going 24/7 and have reached hole number 247. There is a backlog of several kilometers of core stacked on pallets waiting to be logged. Four geologists are hard at work logging core laid out on racks in a big shed. As geologists come and go on field break, or come and go through resignations and new hires, it seldom happens that any one hole is logged in its entirety by the same person. They log on to spread sheets in laptop computers using pre-determined menu options. They have never seen a geological Section (there are none), there are no maps or level plans. The  geological model, such as it is, was produced a year before by an outside consultant who spent ten days on site. Attached by umbilical to a computer in the office is a specialist Ore Reserve Geologist who mostly ignores the gargantuan data base of geological observations (it’s too hard) and calculates a resource on assay data, virtual reality 3D string models and geostatistical techniques. The geologists slaving in the core yard mostly do not care – their job as 100-meter-a-day core-logging operatives is intensely boring — they work as automata and count the days till their next field break, or until they have earned enough money to find some other more intellectually-stimulating employment.

Driving a taxi, perhaps?

Is this the future of core logging in the 21st Century?

These are fictitious projects based on observations of many actual projects, with many companies in different countries and continents over many years. The geologists I describe are not to blame. In many cases it is their first job, they are on short-term contracts, and they are doing what their employer asks and expects of them.

The problem with the approaches I have described above is that the geologists believe the essence of their job is the conversion of light signals from their eyes into digital feed for the computer. A kind of biological digital camera.  Without a pre-existing context in their brain, each observation they make is of equal importance, each pixel of equal weight.  

I don’t know the answers to my rhetorical questions, but fear they might be affirmatives. The geologist-as-camera view is becoming increasingly common and in my experience has generally been disastrous for geological understanding.  Without a good geological map drill holes will be put in the wrong place. Without a good geological model of a deposit the certainty required to convert an Ore Resource into a Proven Reserve can seldom be achieved. 

There is a better way.

The geologist as interrogator

All observation is made in a particular context. The context which should guide the exploration geologist is a matrix of different competing theories about the true nature of the geology being observed.  This context provides the questions that must be asked of each outcrop or piece of drill core.  It defines the search strategy to be followed. It is the search for critical observations that will allow selections between multiple working hypotheses to be made. Important observations are thus prioritised and not lost in a sea of trivial observation. Observation is not about the quality of eyesight, but about the quality of brain and preparedness to use it. Observation is always biased, but the bias is up-front, acknowledged and constantly revised in the face of evidence. Without bias, there is no way of separating signal from noise. But note: this is a quite different kind of bias from the one that seeks only evidence that will confirm a single pre-existing theory – that is what is meant by Confirmation Bias and is rightly condemned.  Anyone who claims to be unbiased merely lacks self-awareness.  Biases may be unconscious or lie in the unstated biases of whoever drew up the detailed procedure manual.

We know how to make you talk

Interrogating your drill core

The correct metaphor for this approach is the geologist as an interrogator of each rock exposure, asking a series of relevant questions that come from his/her views as to what might be happening.

The idea that I have described in the last paragraph of the true nature of scientific investigation as focussed observation guided by emergent theory is a long established and respectable one, as the following quotes from various scientific fields shows:

In Biology:

How odd it is that anyone should not see that all observations must be for or against some view if it is to be of any service. Charles Darwin, 1870

In Fundamental Physics:

We never draw inferences from observations alone, but observations can become significant when they reveal deficiencies in some of the contending explanations. David Deutsch, The Fabric of Reality, 1998.

In the Philosophy of Science:

The facts that we measure or perceive never just speak for themselves but must be interpreted through the coloured lens of ideas…. We can no more separate our theories and concepts from our data than we can find a true Archimedean viewpoint  – a God’s eye view – of ourselves and the world. Michael Schermer, Scientific American, 2007

In Medical Research: cannot find your hypothesis in your results. Before you go to your have to have a specific hypothesis to check. If your hypothesis comes from analysing your data, then there is no sense in analysing the same data again to confirm it. Ben Goldacre, Bad Medicine, 2008.

In Psychology

I am more and more convinced that the only way to obtain clear answers from Nature is to ask her clear questions. Eric Jan Wanamakers, 2014


[1] Every 8 days: it’s in their Contract.

[2] Senior enough, at least, to avoid having to do any field work.

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