We were baking under the summer sun in a stream bed deep in a mountain valley in Eastern Greece. To the east of us, massive limestone cliffs, to the west, the mountain ranges were built from ophiolitic rocks, the stranded remnants of the oceanic crust that had once formed the great Tethys Ocean. We stood in the geological chaos in between, the tortured testament of the collision of continental fragments, the dismemberment of a continental margin, slope and deeper water sediments shovelled on top of the shelf (the limestone cliffs), the whole pile capped by the ripped up pieces of oceanic crust. The year was 1969, this was my thesis area, and it was my task to unravel the chaos.
This was my first season in the field. I’d succeeded in finding hospitable families in two tiny mountain villages who would put me up, and I had become a popular source of entertainment for the communities. I’d figured out my way around, but regretted that the way out from one village in the morning was invariably downhill, meaning that my return in the evening, tired and with a backpack full of rocks was inevitably uphill. But after an initial period of complete confusion, I felt that things were coming along, that I had a workable scheme of what rocks to map, a sense of where the major faults were (the area had suffered further tectonic contortions even after this bit of Tethys had closed), and generally what I needed to do to beat sense out of this geological mess – I had what I thought was a “working model” (it was only later that I discovered the power of “multiple working hypotheses”).
So there we were, perspiring, scrutinising what I would call a scruffy outcrop in this stream bank. It may have been scruffy – small, weathered, and covered in vegetation, but it was critically important. It was red chert, the siliceous sediment from the deep ocean floor; important because it was uniquely located close to the limestones of the continental shelf, and because the silica that makes up chert originates from radiolaria, tiny planktonic critters that build their skeletons out of silica: they offered a possible means of determining the age of these cherts. Lizards scampered across the rock, crickets chirped, and the sun beat down as I explained my hypothesis of how these sediments got to where they were now.
My companion, to whom I was offering my explanation, was my thesis advisor, Alan Smith, whose invitation to help him unravel the story of this part of Tethys had seduced me back from my post-graduate sojourn in the US, and landed me in the middle of this mess. I have written about Alan before, describing his role in the pioneering “fit” of the circum-Atlantic continents; he had arrived in my mapping area a few days before to see how I was getting on, and it was with a mix of enthusiasm and trepidation that I led him around my crucial locations, my key outcrops. We carefully examined these scruffy red cherts, and then I prepared to move on, believing my hypothesis accepted. But Alan paused, and said to me “Could these cherts be upside down?” “I don’t think so,” was my immediate response, although in truth the possibility had never occurred to me. “Well, can you show me?” was Alan’s simple response. It was, of course, an important question – if the tectonic shovelling had turned these sediments upside down, it would be a key element in the story. We resumed our scrutiny, looking for the small internal features in such sediments that indicate which way was up when they were first deposited – we found none. So off we went, scratching around for hours up and down the stream bed to find even scruffier outcrops that might yield some evidence. Eventually we found the clues – and we both agreed that that these rocks were not upside down. We climbed back to the village and the taverna for a cold beer.
Now this sequence of enquiry may seem quite trivial – but for me it certainly wasn’t. Alan’s apparently simple and innocent question had led me realise that I had made an assumption that fit with my hypothesis but which I had never thought to question. From this simple incident, I learned always to stand back, question my assumptions, ask whether I think I know more than I actually do, and examine all the possible questions that could be asked. The incident, the apparently simple question, has stayed with me ever since – for more than forty years I have tried to take nothing at face value, I have doubted and questioned, and I have – I hope – never run off down the path of an initial model, and an immediate working hypothesis, without stopping to think about what the alternatives could be, however unlikely they may seem. Whenever I’ve reminded Alan of this event, he seems surprised – but he has always been a master at asking those apparently simple questions that ultimately turn out to be the keys that unlock a problem, the ideas that turn conventional wisdom on its head and lead to “breakthrough thinking.” I owe him a huge personal debt of intellectual gratitude.