Charles Darwin the geologist
Who was Charles Darwin the geologist? Was he a nephew, or maybe a cousin, of the illustrious naturalist, who first published the theory of evolution by natural selection? I know they had big families… But no, this is the one and the same. It is often forgotten that, early in his career, Charles Darwin was a ‘card-carrying’ geologist.
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Who was Charles Darwin the geologist? Was he a nephew, or maybe a cousin, of the illustrious naturalist, who first published the theory of evolution by natural selection? I know they had big families… But no, this is the one and the same. It is often forgotten that, early in his career, Charles Darwin was a ‘card-carrying’ geologist.
It did not start well. Aged 17, he assessed the Edinburgh University geology lectures he dropped in on, while studying Medicine, so ‘incredibly dull’, that he would ‘never attend to the subject of geology’.
His lecturer was Robert Jameson, who was on the wrong side in the dispute about the origin of dolerite. As dolerite could be found as a layer among strata of sandstone and limestone, he believed it had somehow precipitated out of water. It turned out a sill could be intruded between the layers as red-hot basaltic magma.
In the spirit of student rebellion Charles also assessed all but one of his lecturers in medicine as ‘intolerably dull’. Squeamish about anatomy, he ostensibly switched to the University of Cambridge to study theology. By the summer of 1831 he needed to prove some rapid geological acumen in applying to become the geologist/naturalist on a round-the-world voyage on the survey ship HMS Beagle.
Charles convinced Cambridge Professor Adam Sedgwick to allow him to spend a few weeks as a field assistant while the professor mapped the geology of North Wales. The learning was intensive, but it worked.
While on the Beagle, Darwin’s notes on geology were four times longer than those reporting natural history. He wrote to his sister that ’the pleasure of the first day’s partridge shooting …. cannot be compared to finding a fine group of fossil bones’—there were some great bones to be found in Patagonia.
On returning after almost five years away on the Beagle, Darwin became the society secretary to the Geological Society of London where he remained for three years. He published four scientific papers on geology, including how coral reefs formed above sinking volcanoes.
Less known was Darwin’s solo expedition to investigate the ‘parallel roads’ contouring Glen Roy in the Scottish Highlands. This was a real adventure. From London one could only get as far as Liverpool by train. Like the raised beach deposits he had mapped on the coast of Chile, he visited Glen Roy to record former sea levels.
Another facet of Darwin’s geology emerged on the long walks he took around his wife’s family’s house at Maer near Stoke on Trent. (His own family life was hectic, with ten children.) On one of these walks he discovered an igneous dyke, now named Butterton Dyke, which intruded around the time of the Hebridean volcanoes (one date gives 54 million years ago) but which chemically and by orientation is of mystery origin. To commemorate Darwin, again as a geologist, a fragment of the dyke was sent into orbit on the Mir space station and then flown to a last resting place on the Moon.
Although no longer collecting bones, or dolerite samples, after the 1859 publication of The Origin of Species, he summoned geological evidence to manifest the time needed to allow for evolution. He proposed sluggish rates of erosion of 500-foot-tall Sussex cliffs, such as an inch per century, to explain how much geological time had passed to enable evolution. His estimates for erosion have proved to be perhaps a hundred times too slow and he came under much criticism from physicists who calculated the age of the habitable earth from simple thermal decay. However, by the beginning of a new century, twenty years after his death, the discovery of heating accompanying radioactive decay vindicated his projection of the duration of geological time.
If you were scoring Charles Darwin as a geologist the results would be mixed. Always concocting hypotheses, he was ready to change his theories as new evidence arrived. He admitted there was only one such area of theorizing (the explanation for coral reefs) where he hadn’t had to change his mind. And it was Darwin the geologist who could give Darwin the evolutionist the eons of time required to realise his theory of natural selection.
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