How do you spot something when you don’t know what you’re looking for? How do those brilliant people on TV manage to see signs of recent wildlife activity, or buried buildings, or ancient landscapes? How come you never find fossils when geologists like Roger Osborne tell you that they’re everywhere? Well, you’re not alone.
Every geologist’s favourite story about fieldwork concerns Charles Darwin, the most brilliant observer of the natural world who ever lived. In 1831, when he was 22, Darwin travelled to North Wales with his mentor Adam Sedgwick:
‘We spent many hours in Cwm Idal examining all the rocks with extreme care, as Sedgwick was anxious to find fossils in them.’ Wales was a key place for geologists investigating the Palaeozoic era but, as Darwin wrote later, there was something there that they both missed: ‘Neither of us saw a trace of the wonderful glacial phenomena all around us; we did not notice the plainly scored rocks, the perched boulders, and the lateral and terminal moraines. Yet these phenomena are so conspicuous that a house burnt down by fire could not tell its story more plainly than did this valley.’
So two of the most famous geologists in history did not see the history of the landscape right under their noses. They had an excuse: the idea that ice sheets had covered northern Europe in relatively recent times had not yet been suggested. Once the ice ages were proposed by Louis Agassiz in 1837 geologists began to see evidence for ice sheets everywhere – because now they knew what they were looking for.
This is a neat illustration of the impossibility of what philosophers call ‘the innocent eye’. Whatever we look at, whatever we experience, our vision is always guided by what we already know. Except in childhood, we never see anything with an innocent eye. The same landscape will look completely different once you know how it was formed; the same pebble becomes magical once you know it contains a 150 million-year-old ammonite. Learn a little geology and your world can, quite literally, be transformed.