Ig Nobel Prize-winning geologist on why rocks speak in tongues

Receiving an Ig Nobel Prize is a rare distinction amongst academics, though one you might not display proudly on your mantelpiece. A display cabinet might be a better place for it. Towards the back, perhaps.

But the University of Leicester’s first Ig Nobel Prize winner, Professor Jan Zalasiewicz, who is Emeritus Professor in the School of Geography, Geology and the Environment, is taking it with good humour – especially so, as he thinks that the common perception that science doesn’t have a humorous side can put people off the subject.  

The infamous prize recognises achievements that first make people laugh, then make them think – in Professor Zalasiewicz’s case, for explaining why many scientists like to lick rocks. It begs the question: do they, really?

“Among field geologists of the old school, I’d guess it’s pretty common.” Says Professor Zalasiewicz. “It’s a trick I picked up from my colleagues and mentors back when I was beginning, and it’s one I’ve shown to students on field excursions too - some were a bit surprised, mind! One or two colleagues have since emailed to say that they do it too. It’s a quick and useful technique which we don’t think about much – after a while it becomes almost a reflex.”

Wetting the surface of the rock allows fossil and mineral textures to stand out in sharp relief, allowing the geologist to more easily inspect the specimen in hand. Professor Zalasiewicz is usually better known for his work on the proposal of the Anthropocene – a new geological epoch in which human activities dominate the surface geology of Earth. But six years ago, Professor Zalaesiewicz found himself pondering the origins of this habit, taking to the pages of the Palaeontological Association newsletter to elucidate his thoughts. 

It is that essay that has been recognised with the Ig Nobel Prize for Chemistry and Geology, and true to the spirit of the award, its humorous topic tells us much about where geology has come from. 

Nummulites were an inspiration for Professor Zalasiewicz's essay. Credit: Parent Géry

Today, geologists have a host of techniques available to them to study the composition of rocks, fossils and minerals. In the past, their toolbox was considerably more limited – but their palates, seemingly, more sensitive. Professor Zalasiewicz takes the reader back to the 18th century Italian Giovanni Arduino, an early pioneer in the study of geology, whose letters are filled with descriptions of a multitude of flavours experienced by tasting the burnt, boiled or dissolved remains of his specimens. 

“The account as a whole is redolent with a literary flavour that is part alchemy, part sensual experience of rock, part scientific analysis.” Professor Zalasiewicz explained in his essay.

He adds: “Back then there was very little of this technology, or even systematic knowledge, so the early geologists had to improvise and develop techniques as best as they could – sometimes on commercially important questions, such as to whether to open up a new mine or quarry – so they needed all the help they could get!

“It was in many ways, very different, not just as regards technology, but also the very conceptual basis of geology – with ideas like evolution, plate tectonics and so on not yet developed. Indeed it was Giovanni Arduino who had the insight to recognize a succession of older, more altered and deformed rocks with younger strata above them, in a pattern that eventually formed the basis for the Geological Time Scale. 

“But a few things have stayed constant, like the need to improvise models of the rocks underground based on very incomplete information, and also the fascination with this kind of science. Arduino was clearly an enthusiast – it would have been nice to have met him and talked about rocks!”

While we certainly don’t encourage putting rocks near your mouth in any form, the risks of licking a rock are relatively small amongst the potential hazards of fieldwork as a geologist. And it is not the only habit that still endures.

Professor Zalasiewicz says: “Geological fieldwork can still be very much low-tech and improvisatory, and based on local skills picked up by lots of practical experience, for every terrain is different, and has different problems, and needs different approaches. But there are quite a few techniques that I used as a student – say, recognising the presence of different elements in rocks and minerals by the way that they colour a flame – which are no longer used, because there are now new methods of such geochemical analysis. 

“So the science moves on, but, at heart, it’s plus ça change, plus c’est la même chose…”