The theory also states that these processes have occurred at constant rates throughout natural history. Lyell even went to the Paris Basin to observe the rocks responsible for catastrophism, a theory in direct opposition with uniformitarianism. Based on catastrophism, the forces shaping the earth are not constant. However, when Lyell observed the mass extinction events in the fossil succession of the Paris Basin, he drew a very different conclusion.
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. 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. 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 , the year that Hutton died. Lyell's first volume of "Principles of Geology" was published in , using Hutton and Playfair as starting points.
Charles Darwin brought a copy aboard the Beagle in and later became a close friend of Lyell after completing his voyages in Now, we take for granted the Earth is 4. 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. Giant tropical plants, for example, left their fossils in northern Europe during the Carboniferous Period, never to be seen there again. Life, likewise, had its own arrow through time. Buffon , and later the physicist Joseph Fourier , both claimed that the Earth had begun as a hot ball of molten rock and had been cooling through time.
Fourier argued that the tropical plants of Europe must have lived during those warmer times. Some geologists suggested that the cooling of the planet occasionally triggered violent, sudden uplifts of mountains and volcanic eruptions. Lyell started his career studying under the catastrophist William Buckland at Oxford.
Lyell wanted to find a way to make geology a true science of its own, built on observation and not susceptible to wild speculations or dependent on the supernatural.
For inspiration, Lyell turned to the fifty-year-old ideas of a Scottish farmer named James Hutton. In the s, Hutton had argued that the Earth was transformed not by unimaginable catastrophes but by imperceptibly slow changes, many of which we can see around us today.
Rain erodes mountains, while molten rock pushes up to create new ones. The eroded sediments form into layers of rock, which can later be lifted above sea level, tilted by the force of the uprising rock, and eroded away again.
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