My decision, therefore, to climb the Salisbury Crags in search of a certain section of rock was not taken lightly. Let it never be said that I don’t give my all to this column.
And so, on a Tuesday afternoon, in a fleeting break between showers, I found myself scrambling over volcanic rock in pursuit of an 18th-century geologist’s favourite cliff face. My geological treasure hunt was ill-fated, however. I discovered that accessing the section of rock was out of the question — the area has been fenced-off for safety since 2018, thanks to some serious rock falls.
The Hutton Section is a special section of rock within the Salisbury Crags, a dramatic 46m cliff face located in Holyrood Park, just beside Arthur’s Seat.
This unprepossessing stretch of rock blends easily into the surrounding landscape of cliffs, grass, and footpaths; were it not for the protective fencing and a few small markers embedded in the rock, most people would stroll past without a second thought, unaware that they were passing one of the most important sites in the history of geology.
The exposure itself is a mix of contrasting rock layers; pale, layered sandstone cut into by a darker band of igneous dolerite, itself once molten magma.
Look carefully, and you’ll realise that the sandstone immediately above and below the igneous rock appears almost ‘‘baked’’, like dough that firms and changes in texture when it touches a hot baking tray.
In the late 18th century, the prevailing belief among natural philosophers was that all rocks formed from the gradual precipitation of minerals from ancient oceans. Scottish geologist James Hutton, however, had a different idea.
When Hutton examined this exposure, he realised that the dolerite had intruded into pre-existing sandstone while molten, as evinced by the ‘‘baked edges’’.
Intense heat had clearly been involved — there was no way these igneous rocks ‘‘crystallised like salt from sea water.’’ This discovery became a cornerstone of Hutton’s revolutionary ideas about Earth’s history.
Who was James Hutton? A key figure in the Scottish Enlightenment, Hutton was something of an all-rounder; a geologist, agriculturalist, chemical manufacturer, naturalist and physician, he is often referred to as the father of modern geology.
Born in Edinburgh on June 3, 1726 — it was his 300th birthday recently — the details of Hutton’s life are scant, but what we do know of him is fascinating indeed. After earning a medical degree at the University of Leiden, Hutton spent nearly two decades farming in the Scottish Borders, before returning to Edinburgh in 1768, whereupon he spent almost three decades living at St John’s Hill beneath Salisbury Crags.
Hutton’s great insight was that the Earth was not a static creation but rather a dynamic system, constantly shaped by slow, continuous processes operating over immense spans of time. Instead of explaining the existence of mountains, valleys and rock formations as having occurred through sudden catastrophes (like the Biblical Flood), Hutton argued that certain forces, still visible today — erosion, sedimentation, uplift and volcanic activity—had been at work throughout Earth’s history.
Hutton came to these conclusions through careful observation in the field, such as at the Salisbury Crags.
At Siccar Point on the Berwickshire coast, he encountered evidence that deepened this argument even further: near-vertical layers of ancient greywacke overlain by younger, gently sloping sandstone.
Hutton understood that this geological ‘‘unconformity’’ was proof that cycles of deposition, burial, uplift, erosion and renewed deposition could only be explained by unimaginably vast periods of time.
Thus emerged his revolutionary vision of ‘‘deep time’’, a world with ‘‘no vestige of a beginning, no prospect of an end.’’ The Earth could not be young — there was simply no way the Earth had come into creation only around 6000 years earlier, on October 22, 4004 BC to be precise, according to Archbishop James Ussher of Ireland. (Ussher was dead by this point, else I have no doubt he’d have much to say about Hutton’s theories).
Hutton’s ideas did not emerge in isolation; they arose from a fertile intellectual culture fostered by the Scottish Enlightenment. Eighteenth-century Scotland was awash with thinkers and intellectuals who were united less by any single discipline than by a shared willingness to question inherited assumptions and rethink first principles.
Adam Smith, for example, transformed ideas about wealth and commerce; David Hume challenged conventional understandings of reason and human nature; James Watt revolutionised power and industry.
Hutton’s revelations were made possible in part by the unusually interconnected character of Scottish intellectual life. Hutton moved easily between medicine, chemistry, philosophy, agriculture and geology, enjoying an environment in which scholars, farmers, engineers and physicians might exchange ideas with significant freedom.
His time spent farming in the Borders proved just as important as his formal education — it was on his farm that Hutton was able to observe the slow workings of erosion, soil formation and landscape change. Like his Enlightenment peers, Hutton sought explanations based on evidence rather than tradition or religious authority, applying this approach to the Earth itself.
My parents were Young Earth Creationists; I was brought up believing that the Earth was 6000 years old, that it was created in six literal, 24-hour days, that Earth’s geological features — the sedimentary rock layers and fossils so admired by Hutton — were indicative of the catastrophic, global flood described in Genesis. Family dinners frequently dissolved into heated disputes over carbon dating, evolution, the fossil record, and the age of the Earth itself.
And so, Hutton’s vision of ‘‘deep time’’ was for me not merely a different scientific explanation for the age of the Earth, but a completely different way of understanding reality itself.
I learned to look properly at rocks, with their countless layers recording processes of deposition, uplift, and erosion over immense spans of time. In doing so, I felt as though I was seeing evidence of a history that had always been present but had been hidden from me.
The more I read about Hutton, the more I realise that he challenged not merely a particular interpretation of Genesis, but a way of thinking about certainty itself.
As one raised to see the Earth’s history as already known, encountering Hutton’s concept of deep time in my teenage years was at once unsettling and liberating.
It was thrilling to think about the true age of the Earth and the molten core of our planet; it was mindboggling to consider all those slow, continuous processes operating over immense spans of time.
But perhaps the most profound legacy Hutton has left with me is the realisation that there is a difference between knowledge pursued in service of a conclusion and knowledge pursued as an open-ended investigation.
• Jean Balchin is an ODT columnist who has started a new life in Edinburgh.
