We know that Darwin was a biologist, and in many ways he was the first prominent modern biologist. But many people do not realize that he was also a geologist. Really, he was mainly a geologist on the day he stepped foot on The Beagle for his famous five year tour. This is especially true if we count his work on coral reefs as a geological study, even though coral reefs are a biological phenomenon. After all, the standing model for coral reef formation at the time came from the field of Geology.
Here is a list of several of Darwin’s first publications with their publication dates:
- 1839 Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle. Known to us as “The Voyage of the Beagle”
- 1842 The structure and distribution of coral reefs.
- 1844 Geological observations on the volcanic islands visited during the voyage of H.M.S. Beagle
- 1846 Geological observations on South America.
- 1846 “Note on sandstone and query on coral reefs” contribution to a book
- 1851. Geology (book section)
- 1851 A monograph of the sub-class Cirripedia, with figures of all the species. The Lepadidæ; or, pedunculated cirripedes
- 1851 A monograph on the fossil Lepadidae, or, pedunculated cirripedes of Great Britain.
- 1854. The Balanidae, (or sessile cirripedes); the Verrucidae.
- 1855 A monograph on the fossil Balanidae and Verrucidae of Great Britain
- 1857 Geologia (book section)
- 1859 On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life
There are other items on his publication list, including small contributions to various books, and some letters, not listed here. The nature of publications in the mid 19th century was different from what we see today, so it is hard to define what is a publication and what is not. For the present purposes I’ve excluded Gould’s monographs on birds, which make very heavy use of Darwin’s field descriptions. These were published between 1838 and 1841. I’ve also excluded two book chapters on methods.
Some of these works are clearly about geology, others clearly about biology. Assume that the first item on this list, “The Voyage” is about half geology and half biology. This assumption underestimates the amount of geology and divides a lot of stuff that is neither between the two categories, but a rough estimate is suitable. This list ends with the first edition of Darwin’s “On the Origin of Species…” in 1859. The following graph shows the cumulative word count of writings (given the above caveats and adjustments) for geology vs. biology. I’ve added a rough estimate of Darwin’s contributions to Gould’s bird monographs.
Notice that geology dominates in Darwin’s writings up until the origin. Thereafter, most of Darwin’s published works are biological and not geological (not counting an reprinting or new editions of geological or biological publications) so over time the Biology line would overtake the geology line. But up to this point, Geology dominates.
The leftmost part of this graph, where biology seems to surpass geology, I’m sure, would reverse if I spent more time classifying the verbiage in The Voyage.
Darwin may well have become the world’s greatest biologist, but he started out as a notable geologist. Had he not written The Orign or any later biological work, and never published anything significant on Evolution, Darwin would today be a somewhat obscure but important geologist known to those who study South American geology, volcanic islands, and coral reefs.