When Charles Darwin embarked on the Beagle, he took with him a book written by Charles Lyell: Principles of Geology. In the book, Lyell made the argument for gradualism (or uniformitarianism), the idea that present-day geological processes can explain the history of the earth. When Lyell introduced this concept in 1830, it was a controversial idea; many people relied on the story of the biblical flood to explain the earth's features, though most of Lyell's gentlemen-geologist colleagues did not. Many of them believed that the ancient planet had been much hotter and wetter than the present, with more dramatic geologic processes.
The frontispiece to Lyell's Principles of Geology showed the Temple of Serapis in Italy. At the tops of the stone pillars were dark bands, made of holes drilled by mollusks. Lyell showed the picture to make a point: The pillars had been constructed above ground, later been submerged under water, and finally lifted above sea level. Considering these changes had happened during recorded history, the same geological processes could, during prehistoric times, build mountains, valleys, canyons, and all the other features we see today.
Mount Etna provided Lyell with more evidence of the slow pace of our planet. In between lava layers, he found thick layers of oysters, meaning that the time span between lava flows was significant. And lava flows had built Etna to a height of more than 10,000 feet.
In 1831, King's College, London, awarded Lyell the geology chair. He lasted just three years there. The Church of England dominated the institution's thinking, and Lyell wanted to "free the science from Moses." His situation soon improved and by the late 1830s, he was president of the Geological Society.
Some modern historians have argued that the way Lyell portrayed his intellectual rivals, the catastrophists, was unfair. He accused them of looking to supernatural causes of landscape features, but many of them did no such thing; they simply suspected that events like earthquakes had happened on a larger scale in the geologic past than at present. In fact, using the present to explain the past, as Lyell recommended, is an approach that must be used with caution. Extrapolating from a single year or even a century may not work — such a short time span isn't likely to reproduce all the events that have shaped the landscape. Extrapolating from longer time spans is more effective.
Early on, Lyell had a strong influence on Darwin, but Darwin didn't have the same effect on Lyell. Lyell only reluctantly accepted the theory of evolution; for much of his life, he maintained a steady-state view of the earth and its inhabitants, arguing that as one species went extinct, another appeared. This was partly because of his belief in a long-standing, deep division between humans and animals, in which mankind's superiority to animals was moral, not physical. Between the time he published Principles of Geology in 1830 and Antiquity of Man in 1863, Lyell changed his views. In the first book, he agreed with Cuvier that no humans predated the current epoch. In the second, he extended humanity's existence back in time. His acceptance of Darwinian evolution and human prehistory weren't the only times Lyell had to surrender his beliefs; he also came to support Louis Agassiz's theory of the Ice Age, when gigantic ice sheets covered much of the northern hemisphere in the Pleistocene epoch. Lyell withheld his support of Agassiz's theory for decades, because it stood in direct opposition to his own hypotheses of a steady-state earth.
In addition to uniformitarianism, Lyell's Principles of Geology contained some ideas that seem absurd today, though they struck him as quite reasonable at the time. Lyell concluded that, because the earth undergoes periodic changes in climate and because animals are adapted to certain climates, "huge Iguanodon might reappear in the woods, and the ichthyosaurs in the sea, while pterodactyle might flit again through umbrageous groves of tree ferns." This suggestion invited derision from the academic community, and Henry De la Beche caricatured Lyell in his cartoon Awful Changes (sometimes assumed to be directed at William Buckland).
"You will at once perceive," continued Professor Ichthyosaurus, "that the skull before us belonged to some of the lower order of animals, the teeth are very insignificant the power of the jaws trifling, and altogether it seems wonderful how the creature could have procured food."
Narrative text and graphic design © by Michon Scott - Updated December 12, 2012