Looking back, James Hutton was in the right place at precisely the right time. Hutton was born in 1726, the son of a prosperous merchant and city officeholder in Edinburgh, just a few years before the Scottish capital became a “hotbed of genius” as the epicentre of the Scottish Enlightenment between 1730 and 1820. The environment was primed for big ideas, and Hutton’s concept of uniformitarianism shaped an entire scientific discipline.

Hutton’s big idea was that the earth is millions of years old rather than 6,000 years old, which was based on the literal interpretation of the Bible commonly accepted at the time. His theory of uniformitarianism proposed that rocks and landforms observed at the Earth’s surface today record evidence of past changes and are the result of uniform processes acting over long periods of time. Hutton’s idea challenged the belief that the natural world was static and unchanging, and disrupted the fundamental principle of geology, but it was not easy to convince others and he did not become known as the Father of Modern Geology until well after his death in 1797.

Geology was not Hutton’s first choice. At 14, he was enrolled at the University of Edinburgh to study Latin and philosophy, although his interest in chemistry was piqued by one of his philosophy lecturers during this time.

After graduating in 1743, Hutton briefly worked as a lawyer’s apprentice before re-enrolling at the University of Edinburgh to study science and medicine, and eventually travelled to France and the Netherlands to complete his medical degree. At 23, Hutton established a medical practice in London. It failed to thrive, and he returned to Edinburgh in 1750.

Together with a colleague from University of Edinburgh, James Davie, Hutton built a successful business producing ammonium chloride. The two had experimented with the process years earlier, extracting the valuable salt from chimney soot. Profits from this business and income from several rental properties in Edinburgh supported his travels and research.

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Once financially stable, Hutton set out to visit the two farms he had inherited from his father, and took a keen interest in farming practices. He quickly realized the importance of soil health to farm productivity and began to observe soils, rocks and landscapes on his travels through Scotland, England, and France.

Several now-iconic locations around Scotland had a significant impact on the formation of Hutton’s revolutionary ideas. In 1785, Hutton visited Glen Tilt, a valley in the Cairngorm Mountains of central Scotland, and observed boulders of country rock intruded by veins of granite. He proposed that the granite had been liquid when it intruded the country rock and then cooled. He reinforced this theory with observations near his home at the base of the Salisbury Crags in Edinburgh’s Holyrood Park. Here, at what is now called Hutton’s Section, he studied rocks exposed in a small quarry and concluded that molten volcanic rock had been injected along the planes between sedimentary layers, leading him to propose the idea of uniformitarianism.

At Siccar Point, a rocky headland on the Berwickshire coast east of Edinburgh, Hutton noted in 1788 differences between igneous and sedimentary rocks and evidence of the gradual geomorphic processes, such as weathering and erosion, that form sediments. At what is now a must-see site for geologists, Hutton observed gently dipping Devonian sandstones juxtaposed against vertical Silurian greywackes, the classic angular unconformity.

His blasphemous ideas were not well-received by the clergy or other scientists at the time, although doubt from the latter was partly because of his confusing writing style. Hutton’s Theory of the Earth, originally published in Transactions of the Royal Society of Edinburgh in 1788, was rewritten more clearly and published in 1802 by his friend John Playfair, a professor of natural philosophy at the University of Edinburgh.

Hutton’s work would have a significant impact on future scientists. He was the first to state the principle of natural selection in 1794, suggesting that “...organised bodies… will be best adapted to continue, in preserving themselves and multiplying the individuals of their race” which is thought to have influenced Charles Darwin in developing his ground-breaking 1859 work, On the Origin of Species.

James Hutton’s big ideas became the cornerstone of modern geology, and for that his fellow Edinburgh-born geologist Sir Archibald Geikie named him the Father of Modern Geology.