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Seeing through Lyell's eyes


Sarah Day reports from two events at the British Science Festival this year, organised in association with the Geological Society, which demonstrated the broad range of areas in which geoscientists can have an impact.

Geoscientist Online, 17 September 2009

‘If you can’t paint it, you don’t understand it’.

As a motto for a scientist, this isn’t quite what you’d expect. But it was with this nineteenth century idiom that the first Geological Society sponsored session at this year’s British Science Festival kicked off. Giving the keynote talk at ‘The Great Mars Field Trip’, Dr William Hartmann of the Planetary Science Institute spoke about his love of painting and of planetary science – two areas with more in common than might at first appear.

‘We bring different talents to bear on our science’, he told me later. ‘We shouldn’t assume that the only valid talent is a numerical one’.

This is particularly relevant for planetary scientists, five of whom spoke at the event about their work on understanding Mars based on using Earth as an analogue model. Based on the concept of ‘comparative planetology’, the session was chaired and organised by Dr Matt Balme, a research scientist at the Planetary Science Institute.

‘In terms of geology’, he explained, ‘it’s very hard to start from the ground up and imagine all sorts of new geological processes. Really we’ve only got the Earth to go by, as an analogue for Mars’.

In this context, Hartmann’s emphasis on the importance of creative thinking in science stands out as a vital tool. Painting, like science, is grounded in careful observation. Being able to link seemingly disparate things and draw analogies between them is an invaluable skill shared by scientists and artists alike, and was a methodology demonstrated by all five speakers. In particular, Dr Peter Grindrod of University College London gave an excellent talk about his work on searching for water sources on Mars. Using Epsom salt as an example, he explained how minerals with water bound into their crystal structures might be a potential source of water on Mars – another example of how important analogies with Earth are.

What the session demonstrated was that there are many surprising similarities between Earth and Mars, which can be used to find out more about both planets. It also demonstrated the importance of integrative thinking to the work of scientists. As Hartmann pointed out;

‘There’s a tendency to be encouraged to be a scientist if your brain works in one way. I suspect it’s real that there are brains with multiple talents, and that some of these other talents are now being recognised as being useful in science’.

'The Earth is the key to Mars'

Although this approach is uncovering a huge amount of new information about Mars, such a methodology is one which will be familiar to Earth scientists used to hearing Charles Lyell’s famous motto – ‘the present is the key to the past’.

Lyell’s guiding principle, which remains an important one for geologists today, was to draw analogies between what he observed and what he was studying, using these to reconstruct the geological past. It was the importance of this method to the history of science, and its future development, that the second Geological Society sponsored event, ‘Out of Charles Lyell’s Head’, explored.

Professor Jim Secord of the University of Cambridge, and Dr David Norman from the Sedgewick Museum, discussed the significance of Lyell’s methodology to the development of geology in the nineteenth century, and how important this would become for the work of one of that period’s most famous scientists, Charles Darwin.

Lyell’s Principles of Geology was, among many other things, a total rejection of all things catastrophic. Seeking explanations to geological phenomena ‘by references to causes now in operation’, he had no time for theories of deluges or miracles, grounding his ideas in purest observation. Like the painter, Lyell trusted his own eyes and interpretation of what he saw. As Secord pointed out, this led to some criticism at the time, with cartoons deriding the notion of ‘seeing through Lyell’s eyes’ as obstructive.

Darwin’s theory of evolution could be seen as the culmination of analogical thinking. Using what he learned from Lyell and others about geology, he developed a model for how life may have developed with similar incremental changes. In his talk, David Norman pointed out the striking analogies between Darwin’s geological work, and the theory which would eventually make his name famous.

‘Weathering will allow rocks to evolve in different ways. Fractional crystallisation will subtract from the original melt and lead to diversity in rock types. What he was generating was an approach to all sorts of understandings of how diversity can be generated within the world of rocks’.

In the end, of course, Darwin’s big idea was a biological theory, but it could easily have been an analogous geological one.

‘Darwin was convinced that the dynamic earth had a number of integrated dynamic processes, and he knew intuitively that they were all linked, and that the explanation of the dynamic nature of the world was simple at heart’, Dr Norman explained. ‘He just didn’t know what the heck it was’.

He suspected what he called ‘the grandeur of one motive power, its cause completely unknown, but its action slow, intermittent but irresistible’.

What he was describing, plate tectonics, took another century to be discovered. For Darwin, this was one analogy too far, but it was a theory which he applied to his biological work, with extraordinary impact. As both events demonstrated, geological expertise can be applied to a huge range of subjects, from the study of how life evolved to the question of whether it evolved on other planets. The trick is taking the imaginative leap between them.