Shall we play a word-association game? I’ll say “Darwin.” And chances are, you’ll say “Origin of Species,” or “Evolution,” or “Biology.” Charles Darwin laid the foundation for modern biology. He changed our whole conception of how species come to be, why a single simple organism could be the root of a riotously-branching tree, how “from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.” Of course we associate him with biology. Rightly so.
But I have got a different word associated with him now: “Geology.”
Darwin was one hell of a biologist. But he began and finished with geology, and geology is at the heart of The Origin.
“It is not too much to say that,” Cambridge geology professor John W. Judd said in his introduction to Darwin’s Geological Observations on South America, “had Darwin not been a geologist, the Origin of Species could never have been written by him.” Strong words, you say. Of course a geologist would be partial, but perhaps he overstates the case. Except. Except. Some of the most powerful arguments in The Origin are centered in geology. He understood the geological record, and what that meant for the fossil record. He understood how geology impacted species. There, in chapters IX and X, taking center stage, is geology. No geology, no Origin – not as we know it.
Or perhaps I should say, no Lyell, no Origin. Because it was Charles Lyell and his Principles of Geology that had the greatest influence on Darwin’s scientific thought. Darwin’s writings are liberally salted with paens to Lyell. In his Autobiography, he shows just how much influence Lyell had on his thinking, influence that led directly to the powerfully-organized arguments of The Origin: “After my return to England it appeared to me that by following the example of Lyell in Geology, and by collecting all facts which bore in any way on the variation of animals and plants under domestication and nature, some light might perhaps be thrown on the whole subject.”
Anyone who has read The Origin understands just how thorough Darwin was in collecting and marshaling his facts. One of the most critical facts was the immensity of the timescales involved. In Chapter IX, it becomes exquisitely clear that geology prepared Darwin’s mind for seeing those years in their uncountable millions. “It is hardly possible for me even to recall to the reader, who may not be a practical geologist, the facts leading the mind feebly to comprehend the lapse of time,” he wrote. “He who can read Sir Charles Lyell’s grand work on the Principles of Geology, which the future historian will recognise as having produced a revolution in natural science, yet does not admit how incomprehensibly vast have been the past periods of time, may at once close this volume.” Without an understanding of the age of the Earth, an understanding of evolution is impossible. We take it for granted now. Then, it was still a new idea, and without it, Darwin may have never been able to conceive of evolution as the engine of all the diversity of life.
Geology is intimately related to evolution. That is a fact that gets obscured; you don’t hear of Darwin as geologist in biology classes. He never got so much as a mention in my geology class; when I come across him in books on geology, it’s usually in reference to his work on evolution by way of explaining how fossils can be used for dating rocks. A person could be forgiven for thinking he was a biologist first and last. But his first passion was geology. Field observations on the geology he saw while sailing with the Beagle filled half his manuscript pages. Geology formed the subject for some of his first books: it comprises major portions of his Voyage of the Beagle; it helped build the foundation for The Origin; and in 1881, he returned to geology one again with his “The Formation of Vegetable Mould, through the Action of Worms” – a treatise on soils. He was a Fellow of the Geological Society of London. Geology was his first scientific love, and he returned to her again and again.
Without evolution, Darwin may not have achieved the same fame, but he wouldn’t have been forgotten. His contributions to geology were far from inconsequential. He laid some of the foundation stones for the young science. His work on coral reefs, his recognition that granitic rocks and lava rocks were essentially the same, his work on volcanic islands, and crustal movements in South America, would have ensured him a place among the giants of geology. Students may not have instantly recognized his name, and fundamentalist pastors may not have thundered against him, but he still would have been a recognized and respected scientist.
We’ll be exploring Darwin the Geologist in some depth. By the end of the voyage, it’s my fondest hope that the next time we play the Darwin Word Association Game, you’ll shout “Geology!” without a second’s hesitation.
Works by Charles Darwin:
Sir Archibald Giekie, Charles Darwin as geologist. The Rede lecture given at the Darwin centennial commemoration on 24 June 1909.