On a June afternoon in 1788, James Hutton stood before a rock outcropping on Scotland’s western coast named Siccar Point. There, before a couple of other members of the Scottish Enlightenment, he staked his claim as the father of modern geology.

Aa Hutton told the skeptics who accompanied him there by boat, Siccar Point illustrated a blasphemous truth: the Earth was old, almost beyond comprehension.

Three years earlier, he’d unveiled two papers, together called "Theory of the Earth," at a pair of meetings of the Royal Society of Edinburgh. Hutton proposed that the Earth constantly cycled through disrepair and renewal. Exposed rocks and soil were eroded, and formed new sediments that were buried and turned into rock by heat and pressure. That rock eventually uplifted and eroded again, a cycle that continued uninterrupted.

“The result, therefore, of this physical enquiry,” Hutton concluded, “is that we find no vestige of a beginning, no prospect of an end.”

His ideas were startling at a time when most natural philosophers—the term scientist had not yet been coined—believed that the Earth had been created by God roughly 6,000 years earlier. The popular notion was that the world had been in a continual decline ever since the perfection of Eden. Therefore, it had to be young. The King James Bible even set a date: October 23, 4004 BC.

At Siccar Point, Hutton pointed to proof of his theory: the junction of two types of rock created at different times and by different forces. Gray layers of metamorphic rock rose vertically, like weathered boards stuck in the ground. They stabbed into horizontal layers of red, layered sandstone, rock only beginning to be deposited. The gray rock, Hutton explained, had originally been laid down in horizontal layers of perhaps an inch a year of sediment long ago. Over time, subterranean heat and pressure transformed the sediment into rock and then a force caused the strata to buckle, fold and become vertical.

Here, he added, was irrefutable proof the Earth was far older than the prevailing belief of the time.

John Playfair, a mathematician who would go on to become Hutton's biographer with his 1805 book, Life of Dr. Hutton, accompanied him that day. “The mind seemed to grow giddy by looking so far back into the abyss of time; and whilst we listened with earnestness and admiration to the philosopher who was now unfolding to us the order and series of these wonderful events, we became sensible how much further reason may sometimes go than imagination may venture to follow,” he late wrote.

Hutton, born in 1726, never became famous for his theories during his life. It would take a generation before the geologist Charles Lyell and the biologist Charles Darwin would grasp the importance of his work. But his influence endures today.

"A lot of what is still in practice today in terms of how we think about geology came from Hutton," says Stephen Marshak, a geology professor at the University of Illinois who has made the pilgrimage to Siccar Point twice. To Marshak, Hutton is the father of geology.

Authors like Stephen Jay Gould and Jack Repcheck—who wrote a biography of Hutton titled The Man Who Found Time—credit him with freeing science from religious orthodoxy and laying the foundation for Charles Darwin’s theory of evolution.

"He burst the boundaries of time, thereby establishing geology's most distinctive and transforming contribution to human thought—Deep Time," Gould wrote in 1977.

Hutton developed his theory over 25 years, first while running a farm in eastern Scotland near the border with England and later in an Edinburgh house he built in 1770. There, one visitor wrote that "his study is so full of fossils and chemical apparatus of various kinds that there is barely room to sit down."

He was spared financial worries thanks to income from the farm and other ventures, and had no dependent family members, because he never married. Thus freed of most earthly burdens, he spent his days working in the study and reading. He traveled through Scotland, Wales and England, collecting rocks and surveying the geology. Through chemistry, he determined that rocks could not have precipitated from a catastrophe like Noah’s Flood, the prevailing view of previous centuries, otherwise they would be dissolved by water. Heat and pressure, he realized, formed rocks.

That discovery came with help from Joseph Black, a physician, chemist and the discoverer of carbon dioxide. When Hutton moved to Edinburgh, Black shared his love of chemistry, a key tool to understanding the effect of heat on rock. He deduced the existence of latent heat and the importance of pressure on heated substances. Water, for instance, stays liquid under pressure even when heated to a temperature that normally would transform it to steam. Those ideas about heat and pressure would become key to Hutton’s theory about how buried sediments became rock.

Black and Hutton were among the leading lights of the Royal Society of Edinburgh, along with Adam Smith, the economist and author of The Wealth of Nations, David Hume, the philosopher, Robert Burns, the poet, and James Watt, the inventor of the two-cylinder steam engine that paved the way for the Industrial Revolution.

Hutton's principle of uniformitarianism—that the present is the key to the past—has been a guiding principle in geology and all sciences since. Marshak notes that despite his insight, Hutton didn’t grasp all the foundations of geology. He thought, for example, that everything happened at a similar rate, something that does not account for catastrophic actions like mountain building or volcanic eruptions, which have shaped the Earth.

Unlike many of his contemporaries, Hutton never found fame during his life. But his portrait of an ever-changing planet had a profound effect. Playfair's book fell into favor with Charles Lyell, who was born in 1797, the year that Hutton died. Lyell's first volume of "Principles of Geology" was published in 1830, using Hutton and Playfair as starting points.

Charles Darwin brought a copy aboard the Beagle in 1832 and later became a close friend of Lyell after completing his voyages in 1836. Darwin’s On the Origins of Species owes a debt to Hutton’s concept of deep time and rejection of religious orthodoxy.

"The concept of Deep Time is essential. Now, we take for granted the Earth is 4.5 billion years old. Hutton had no way of knowing it was that kind of age. But he did speculate that the Earth must be very, very old," Marshak says. "That idea ultimately led Darwin to come up with his phrasing of the theory of evolution. Because only by realizing there could be an immense amount of time could evolution produce the diversity of species and also the record of species found in fossils."

"The genealogy of these ideas," he adds, "goes from Hutton to Playfair to Lyell to Darwin."